632 PART SEVEN Ecology Figure 32.6 Ecotourism. for many marine species. Most coastal ecosystems are not as bountiful as they once were because of deforestation upriver. Whale watchers experience the thrill of seeing a humpback whale surfacing. Regulation of Climate © Chase Dekker Wildlife Images/Getty RF At the local level, trees provide shade, block drying winds, and 32.2 CONNECTING THE CONCEPTS reduce the need for fans and air conditioners during the summer. Globally, forests regulate the climate, because they take up carbon The Earth’s biodiversity has dioxide, a greenhouse gas. When the leaves of trees photosynthe- tremendous value to humans, size, they use carbon dioxide, which is stored as the wood of the but it is under stress. tree. When trees are cut and burned, carbon is no longer released into the soil through natural decomposition; instead, carbon diox- ide is released into the atmosphere. Subsequently, the reduction of forests worldwide reduces the amount of carbon dioxide removed from the atmosphere, amplifying the buildup of that greenhouse gas. Deforestation often removes soil nutrients needed by future tree generations, which in turn limits reforestation. Ecotourism Almost everyone prefers to vacation in the natural beauty of an ecosystem (Fig. 32.6). In the United States, nearly 100 million people enjoy vacationing in a natural setting. To do so, they spend nearly $5 billion each year on fees, transportation, lodging, and food. Many tourists want to go sport fishing, whale watching, boat riding, hiking, bird watching, and the like. Some merely want to immerse themselves in the beauty of a natural environment. Some less-developed countries are realizing that there is significant economic potential in developing their ecotourism industry. Check Your Progress 32.2 1. Summarize the direct and indirect values of biodiversity. 2. Explain how modern medicine and agriculture are dependent on biodiversity. 3. Explain how the preservation of biodiversity can help reduce the problems associated with overexploitation of water, land, food, or energy resources. 32.3 Resources and Environmental Impact Learning Outcomes Upon completion of this section, you should be able to 1. Describe the efects of human populations on land and water resources. 2. Describe how modern farming methods impact the environment, and explain how the “green revolution” may help alleviate these problems. 3. Explain how the use of fossil fuels and the production of pollution impact the environment. Humans use resources to meet their basic needs. Land, water, food, energy, and minerals are the maximally used resources (Fig. 32.7).
Human population CHAPTER 32 Human Impact on the Biosphere 633 land water food energy Figure 32.7 Resources. Humans use land, water, food, energy, and minerals to meet their needs, including a place to live, food to eat, and products that make their lives easier. (population): © Jan Hanus/Alamy; (land): © Doug Menuez/Getty RF; (water): © Evelyn Jo Johnson; (food): © McGraw-Hill Education, John Thoeming, photographer; (energy): © PhotoLink/Getty RF; (minerals): © T. O’Keefe/ PhotoLink/Getty RF minerals Some resources are nonrenewable, and some are renewable. Nonrenew- able resources are limited in supply. For example, the amount of land, fossil fuels, and minerals is finite and can be exhausted. Better extraction methods and efficient use can make the supply last longer, but eventually these re- sources will run out. Renewable resources are unlimited in supply. We can use water and certain forms of energy (e.g., solar energy) or harvest plants and animals for food, and more will always be forthcoming. However, even though these resources are renewable, we must be careful not to overconsume them. Consider that most species have a population threshold below which the population cannot recover or sustain its numbers, as when the huge herds of buffalo that once roamed the western United States disappeared after being overexploited. Unfortunately, one side effect of resource consumption is pollution. Pollution is any alteration of the environment in an undesirable way. Pollution is often caused by human activities. The human impact on the environment is proportional to the size of the population and consumption of the resources. As the population grows, so does the need for resources and the amount of pollu- tion generated by using these resources. Consider that seven people adding waste to the ocean might not be alarming, but 7 billion people doing so would certainly affect its cleanliness. In modern times, the consumption of mineral and energy resources has grown faster than population size. People in the more-developed countries (MDCs) use a disproportionate amount of these resources. Land People require a physical place to live. Worldwide, there are more than 47 people for each square kilometer of available land, including Antarctica, mountain ranges, jungles, and deserts. Naturally, land is also needed for a variety of uses aside from homes, such as agriculture, electric power plants, manufacturing plants, highways, hospitals, and schools. Beaches and Human Habitation At least 40% of the world population lives within 100 km (60 mi) of a coast- line, with this number increasing each year. In the United States, over half of the population lives within 80 km (50 mi) of the coasts (including the Great
634 PART SEVEN Ecology Key: Lakes). Living right on the coast has a negative im- pact, because it accelerates natural beach erosion Severely eroded and loss of habitat for marine organisms. Moderately eroded San Francisco New Beach Erosion An estimated 70% of the world’s Los Angeles York beaches are eroding; Figure 32.8a shows how ex- tensive this problem is along coasts of the United a. Norfolk States. The seas have been rising for the past 12,000 years, ever since the climate turned warmer after Charleston the last Ice Age, and consequently the forces New Orleans associated with waves, tides, and wind have been amplified. Humans often participate in activities that di- vert more water to the oceans, contributing to rising seas and beach erosion. For example, humans have filled in coastal wetlands, such as mangrove swamps in the southern United States and saltwater marshes in the northern United States formerly considered “wastelands.” With growing recogni- tion of the services provided by wetlands, wetland conservation and restoration has been growing in the United States during the past 40 years. There are multiple reasons to protect coastal wetlands. They serve as spawning areas for fish and other forms of marine life as well as buffers against hur- ricane storm surges, and they reduce shoreline ero- sion. They are also habitats for certain terrestrial species, including many types of birds. Humans often try to stabilize beaches by b. building groynes (structures that extend from the Figure 32.8 Beach erosion. beach into the water) and seawalls. Groynes trap sand and build beaches on one side as well as slowing the longshore currents, a. Most of the U.S. coastline is subject to beach erosion. b. Therefore, but erosion is increased on the other side. Seawalls, in the end, also increase people who choose to live near the coast may eventually lose their erosion because ocean waves remove sand from in front of and to the sides of homes. these walls. Importing sand is a better solution, but it is very costly and can (b): © Tyrone Turner/Getty Images disturb plant and animal populations. It’s estimated that the U.S. shoreline loses 40% more sediment than it receives, because the building of dams pre- vents sediment from reaching the coast. Coastal Pollution The coasts are particularly subject to pollution because toxic substances placed in freshwater lakes, rivers, and streams may eventually find their way to a coast. Oil spills at sea also cause localized harmful effects. Semiarid Lands and Human Habitation Forty percent of the Earth’s lands are already deserts, and any land adjacent to a desert is in danger of becoming desert if humans manage it improperly. Desertification is the conversion of semiarid land to desertlike conditions (Fig. 32.9). Quite often, desertification begins when humans allow animals to over- graze the land. The soil can no longer hold rainwater, which runs off instead of keeping the remaining plants alive or recharging wells. Humans then remove whatever vegetation they can find to use as fuel or fodder for their animals. The end result is a desert unable to support agriculture, which is then
abandoned as people move on to continue the process someplace else. CHAPTER 32 Human Impact on the Biosphere 635 Some estimate that nearly three-quarters of all rangelands world- wide are in danger of desertification. The famine in Ethiopia Key: during 2002–2003 was due, at least in part, to degradation of the desert land to the point that it could no longer support humans and desertification risk their livestock. desertification Tropical Rain Forest and Human Habitation Figure 32.9 Desertiication. Deforestation, the removal of trees that reduces the extent of a Desertiication is a worldwide occurrence that reduces the amount forest (Fig. 32.10), has long allowed humans to live in areas of land suitable for human habitation. where forests once covered the land. The concern recently has Data from A. Goudie and I. Wilkinson, The Warm Desert Environment. Copyright been that people are settling in tropical rain forests, such as the 1977 by Cambridge University Press, New York Amazon, following the building of roads. This land, too, is subject to desertification. Soil in the tropics is often thin and nutrient-poor because all the nutrients are tied up in the trees and other vegetation. When the trees are felled and removed and the land is used for agriculture or grazing, it quickly loses its fertility and becomes subject to desertification. Other consequences of deforestation are a loss of biodiversity and an increase in atmospheric carbon dioxide. The trees that once took in and stored carbon dioxide have been removed. The destruction of tropical rain forests causes the extinction of a large number of species that have value to humans. Water Key: 10,000 today yrs ago Access to clean drinking water is considered a human right, but actually most fresh water is used by agriculture and industry (Fig. 32.11a,b). In temperate the United States, approximately 39% of all fresh water is used to irri- forests gate crops! Much of a recent surge in demand for water stems from tropical increased industrial activity and irrigation-intensive agriculture, the forests type of agriculture that now supplies about 40% of the world’s food crops. Domestically, in the more-developed countries (MDCs), more water is usually used for bathing, flushing toilets, and watering lawns than a. for drinking and cooking (Fig. 32.11c). In the water-poor areas of the world, people may not have ready access to drinking water, and if they do, the water may be unclean. Increasing Water Supplies Although the needs of the human population overall do not exceed the renewable supply, this is not the case in certain regions of the world. As illustrated in Figure 32.9, about 40% of the world’s land is desert, and deserts are bordered by semiarid land. When necessary to support human population growth, the supply of fresh water is increased by damming riv- ers and withdrawing water from aquifers. Dams The world’s 45,000 large dams catch 14% of all precipitation runoff, provide water for up to 40% of irrigated land, and give some 65 countries more than half their electricity. Damming of certain rivers b. Figure 32.10 Deforestation. has been so extensive that they no longer flow as they once did. The a. Nearly half of the world’s forest lands have been cleared for Yellow River in China fails to reach the sea most years; the Colorado River farming, logging, and urbanization. b. The soil of tropical rain forests is not suitable for long-term farming. barely makes it to the Gulf of California; and even the Rio Grande dries up (b): © Eco Images/Universal Images Group/Getty Images before it can merge with the Gulf of Mexico. The first and third longest riv- ers on Earth, the Nile in Egypt and the Ganges in India, respectively, are
636 PART SEVEN Ecology a. Agriculture uses most of the fresh water consumed. also so overexploited that, at some times of the year, they hardly make it to the ocean. b. Industrial use of water is about half c. Domestic use of water that of agricultural use. is about half that of Dams have additional drawbacks: (1) Reservoirs behind the dam lose industrial use. water due to evaporation and seepage into underlying rock beds. The amount of water lost sometimes equals the amount made available! (2) The salt left Figure 32.11 Global water use. behind by evaporation and agricultural runoff can make a river’s water un- usable farther downstream. (3) Sediment buildup causes dams to hold back a. Agriculture uses water primarily for irrigation. b. Industry uses less water; with time, dams may become useless for storing water. (4) The water in various ways. c. People use water for drinking, bathing, reduced amount of water below the dam has a negative impact on native lushing toilets, and watering lawns. wildlife. (a): © Corbis RF; (b): © Jeremy Samuelson/Photolibrary/Getty Images; Aquifers To meet their freshwater needs, people are pumping vast amounts (c): © Stockbyte/PunchStock RF of water from aquifers, which are natural reservoirs of water found below the surface of the Earth. Aquifers hold about 1,000 times the amount of water that falls on land as precipitation each year. This water accumulates from rain that fell over long periods of time. In the past 50 years, groundwater deple- tion has become a problem in many areas of the world. In substantial portions of the High Plains Aquifer, which stretches from South Dakota to the Texas Panhandle in the central United States, much water is pumped out for irriga- tion or for household use. In the 1950s, India had 100,000 motorized pumps in operation; today, India has 20 million pumps, a huge increase in ground- water pumping. Environmental Consequences Removal of water causes subsidence, settling of the soil as it dries out, which causes the surface to lower. In Califor- nia’s San Joaquin Valley, an area of more than 13,000 km2 has subsided, and in the worst spot the surface has dropped more than 9 m! In some parts of Gujarat, India, the water table has dropped as much as 7 m. Subsidence damages canals, buildings, and underground pipes. Withdrawal of groundwater can cause sink- holes, as when an underground cavern collapses because water no longer holds up its roof. Saltwater intrusion is another consequence of groundwater depletion. The flow of water from streams and aquifers usually keeps them fairly free of seawater. But as water is withdrawn, the water table can lower to the point that seawater backs up into streams and aquifers. Saltwater intrusion reduces the supply of fresh water along the coast. Connections: Environment How much water is required to produce your food? Growing a single serving of lettuce takes about 6 gallons of water. Producing an 8-oz glass of milk requires 49 gallons. That includes the amount of water the cow drinks, the water used to grow the cow’s food, and the water needed to pro- cess the milk. Producing a single serving of steak consumes more than 2,600 gallons of water. © PhotoSpin, Inc./ Alamy RF
Conservation of Water CHAPTER 32 Human Impact on the Biosphere 637 By 2025, two-thirds of the world’s population may be living in countries that a. Drought-resistant plants are facing serious water shortages. Many solutions for expanding water sup- plies are available (Fig. 32.12). Using drip irrigation delivers more water to tubing crops and saves about 50% over traditional methods while increasing crop b. Drip irrigation yields. Although the first drip systems were developed in 1960, they are used on less than 1% of irrigated land. Most governments subsidize irrigation so Figure 32.12 Conservation measures to save water. heavily that farmers have little incentive to invest in drip systems or other water-saving methods. Planting drought- and salt-tolerant crops would decrease a. Planting drought-resistant plants in parks and gardens and the water required for agriculture. Recycling water and adopting conservation drought-resistant crops in ields cuts down on the need to irrigate. measures could help the world’s industries cut their water demands by more b. Drip irrigation delivers water directly to the roots. than half. (a): © Bruno Barbier/Getty Images; (b): © Inga Spence/Alamy Food In 1950, the human population numbered 2.5 billion, and there was only enough food to provide less than 2,000 calories per person per day; now, with over 7.4 billion people on Earth, the world food supply provides more than 2,500 calories per person per day. Generally speaking, food comes from three activities: growing crops, raising animals, and fishing the seas. Unfortunately, modern farming methods, which have increased the food supply, include some harmful practices: 1. Planting of a few genetic varieties. The majority of farmers practice monoculture, meaning that they plant a single type (strain) of crop throughout their fields. Unfortunately, the resulting lack of genetic diver- sity means that a single type of parasite or disease can infect the entire crop. This scenario does not take into account any genetic variants that may exhibit disease resistance. 2. Heavy use of fertilizers, pesticides, and herbicides. Fertilizer production is energy-intensive, and fertilizer runoff contributes to water pollution. Pesticides reduce soil fertility, because they kill beneficial soil organisms as well as pests, and some pesticides and herbicides are linked to the development of cancer. 3. Generous irrigation. Water is sometimes taken from aquifers whose wa- ter content may in the future become so reduced that it could become too expensive to pump out any more. 4. Excessive fuel consumption. Irrigation pumps remove water from aqui- fers, and large farming machines are used to spread fertilizers, pesticides, and herbicides, as well as to sow and harvest the crops. In effect, modern farming methods transform fossil fuel energy into food energy. Figure 32.13 shows ways to minimize the harmful effects of modern farming practices. Soil Loss and Degradation Land suitable for farming and for grazing animals is being degraded world- wide. Topsoil, the topmost portion of the soil, is the richest in organic matter and the most capable of supporting grass and crops. When bare soil is acted on by water and wind, soil erosion occurs and topsoil is lost. As a result, marginal rangeland becomes desert, and farmland loses its productivity. The custom of planting the same crop in straight rows that facilitate the use of large farming machines has caused the United States and Canada to have one of the highest rates of soil erosion in the world. Conserving the nutrients
638 PART SEVEN Ecology a. Polyculture now being lost could save farmers $20 billion annually in fertilizer costs. Much of the eroded sediment ends up in lakes and streams, where it reduces the abil- b. Contour with no-till farming ity of aquatic species to survive. Figure 32.13 Conservation Almost all water contains dissolved salts, and these salts are left behind when either plants take up the water or the water evaporates. Between 25% methods. and 35% of the irrigated western croplands are thought to have undergone salinization, an accumulation of mineral salts generated through irrigation. a. Polyculture reduces the ability Salinization makes the land unsuitable for growing crops. of one parasite to wipe out an Green Revolutions entire crop and reduces the need About 50 years ago, research scientists began to breed tropical wheat and rice varieties specifically for farmers in the LDCs. The dramatic increase in yield to use an herbicide to kill weeds. c. Biological pest control due to the introduction of these new varieties around the world was called “the This farmer has planted alfalfa green revolution.” These plants helped the world food supply keep pace with the rapid increase in world population. However, most of these plants are between strips of corn, which also replenishes the nitrogen content called “high responders” because they need high levels of fertilizer, water, and pesticides in order to produce a high yield. In other words, they require the of the soil (instead of adding fertilizers). b. Contour with no-till same subsidies and create the same ecological problems as do modern farm- ing methods. farming conserves topsoil, because water has less tendency to run Genetic Engineering Genetic engineering can produce transgenic plants of. c. Instead of pesticides, it is sometimes possible to use a natural with new and different traits, among them resistance to both insects and herbicides (see Section 12.3). When herbicide-resistant crops are planted, predator. Here a ladybug is eating aphids of a cultivated crop plant. weeds are easily controlled, less tillage is needed, and soil erosion is minimized. Researchers also want to produce crops that tolerate salt, (a): © David R. Frazier/Science Source; (b): © AgStock Images, Inc./Alamy; drought, and cold. In addition, some progress has been made in increas- (c): © Perennou Nuridsany/Science Source ing the food quality of crops, so that they will supply more of the pro- teins, vitamins, and minerals people need. Genetically engineered crops are resulting in another green revolution. Nevertheless, some people are opposed to the use of genetically engineered crops, fearing that they will dam- age the environment and lead to health problems in humans. Domestic Livestock A low-protein, high-carbohydrate diet consisting only of grains, such as wheat, rice, or corn, can lead to malnutrition. In the LDCs, kwashiorkor, a condition caused by a severe protein deficiency, is seen in infants and children ages 1–3; this deficiency tends to develop after a new baby arrives in the family and the older children are no longer breast-fed. Such children are lethargic and irrita- ble, and they have bloated abdomens. The condition often results in intellectual disabilities. In the MDCs, many people tend to have more than enough protein in their diet. Almost two-thirds of U.S. cropland is devoted to producing livestock feed. This means that a large percentage of the fossil fuel, fertilizer, water, herbicides, and pesticides we use are actually for the purpose of raising live- stock. Typically, cattle are range-fed for about four months, and then they are taken to crowded feedlots, where they receive growth hormone and antibiotics while feeding on grain. Most pigs and chickens spend their entire lives in crowded pens and cages (Fig. 32.14). Figure 32.14 Crowding of livestock. Hogs milling in feedlot pens. © Arterra Picture Library/Alamy
Just as livestock eat a large proportion of the crops in the United States, CHAPTER 32 Human Impact on the Biosphere 639 raising livestock accounts for much of the pollution associated with farming. Consider also that fossil fuel energy is needed not just to produce herbicides a. Fishing by use of a drag net and pesticides and to grow food but also to make the food available to the live- stock. Raising livestock is extremely energy-intensive in the MDCs. In addi- b. Aqua farming tion, water is used to wash livestock wastes into nearby bodies of water, where they add significantly to water pollution. Raw animal wastes are not always Figure 32.15 Fishing. regulated in the same fashion as human wastes. The world ish catch has declined in recent years (a) because For these reasons, it is prudent to recall the ecological pyramid (see modern ishing methods are overexploiting isheries. b. Aqua Fig. 31.20), which shows that, as you move up a food chain, energy is lost. As farming, the raising of aquatic organisms in controlled settings, is a rule of thumb, for every 10 calories of energy from a plant, only 1 calorie is decreasing the demand placed on the oceans. available for the production of animal tissue in an herbivore. In other words, it (a): © StrahilDimitrov/Getty RF; (b): © Michael Pole/Corbis is possible to feed 10 times as many people on grain as on meat. Fishing Since 2000, the world fish catch has been on the decline. Worldwide, between 1970 and 1990, the number of large boats devoted to fishing doubled to 1.2 million. The U.S. fishing fleet participated in this growth due to the avail- ability of federal loans for building fishing boats. The new boats have sonar and depth recorders, and their computers remember the sites of previous catches, so that the boats can go there again. Helicopters, planes, and even satellite data are used to help find fish. The number of North Atlantic sword- fish caught in the United States declined 70% from 1980 to 1990, and the aver- age weight fell from 115 to 60 pounds. The Atlantic bluefin tuna is so overfished that it may never recover and instead become extinct. Modern fishing practices negatively impact biodiversity, because a large number of marine animals are caught by chance in the huge nets some fishing boats use (Fig. 32.15a). These animals are discarded. The world’s shrimp fishery has an annual catch of 1.8 million tons, but the other animals caught and discarded in the process amount to 9.5 million tons. Raising tuna, shrimp, and other aquatic organisms in controlled settings, called aqua farm- ing, has reduced the fishing pressures on wild populations (Fig. 32.15b). In fact, over 90% of the shrimp available in the United States are produced via aquaculture. Energy About 6% of the world’s energy supply comes from nuclear power, and 81% comes from fossil fuels; both of these are finite, nonrenewable sources. Al- though it was once predicted that the nuclear power industry would fulfill a significant portion of the world’s energy needs, this has not happened for two reasons: (1) People are very concerned about the potential for disasters at nuclear power plants, such as those that occurred at Chernobyl (1986) and Fukushima (2011). (2) Radioactive wastes from nuclear power plants remain a threat to the environment for thousands of years, and we still have not deter- mined the best way to store them safely. As you learned in Section 31.2, oil, natural gas, and coal are fossil fuels—the compressed remains of organisms that died millions of years ago. The MDCs presently consume more than twice as much fossil fuel as the LDCs, yet there are many more people in the LDCs than in the MDCs. It has been estimated that each person in the MDCs uses approximately as much energy in a day as a person in an LDC does in a year. Among the fossil fuels, oil burns more cleanly than coal, which may contain a considerable amount of sulfur. Thus, despite the fact that the United
640 PART SEVEN Ecology States has a good supply of coal, imported oil is our preferred fossil fuel. Even so, the burning of any fossil fuel contributes to environmental problems, Figure 32.16 Efects of fossil fuel use. because, as it burns, pollutants are emitted into the air. Mean global temperature is rising due to the introduction of As discussed in Section 31.2, the burning of fossil fuels is elevating the greenhouse gases into the atmosphere. A temperature rise of only concentration of greenhouse gases in the atmosphere. Countless scientific a few degrees causes coral reefs to “bleach” and become lifeless. studies have determined that the elevation of carbon dioxide in the atmosphere The majority of the Great Barrier Reef has already died of due to is contributing to global warming and global climate change. Since the oceans coral bleaching. absorb a large amount of the excess carbon dioxide in the atmosphere, they are © Len Zell/Getty Images susceptible to warming and acidification (Figure 32.16). a. Renewable Energy Sources Renewable energy sources include wind power, hydropower, geothermal en- ergy, and solar energy (Fig. 32.17). Wind Power Wind power is expected to account for a significant percentage of our energy needs in the future. A community that generates its own electric- ity using wind power can solve the problem of uneven energy production by selling electricity to a local public utility when an excess is available and buy- ing electricity from the same facility when wind power is in short supply. Hydropower Hydroelectric plants convert the energy of falling water into electricity. Hydropower accounts for about 6% of the electric power generated in the United States and almost 67% of the total renewable energy used. Much of the hydropower development in recent years has been due to the construc- tion of enormous dams, which have detrimental environmental effects. An alternative choice may be small-scale dams that generate less power per dam but do not have the same environmental impact. Geothermal Energy Elements such as uranium, thorium, radium, and pluto- nium undergo radioactive decay below the Earth’s surface and then heat the sur- rounding rocks to hundreds of degrees Celsius. When the rocks are in contact with underground streams or lakes, huge amounts of steam and hot water are produced. This steam can be piped up to the surface to supply hot water for home heating or to run steam-driven turbogenerators. California’s Geysers project is the world’s largest geother- mal electricity-generating complex. Energy and the Solar-Hydrogen Revolution Solar energy is diffuse energy that must be (1) collected, c. (2) converted to another form, and Figure 32.17 Renewable energy sources. a. Wind power requires land on which to place enough windmills to generate energy. b. Hydropower dams provide a clean form of energy but can be ecologically disastrous in other ways. c. Photovoltaic cells on rooftops can collect difuse solar energy more afordably than in the past. b. (a): © Glen Allison/Getty RF (b): © Corbis RF; (c): © Danita Delimont/Getty Images
CHAPTER 32 Human Impact on the Biosphere 641 (3) stored if it is to compete with other available forms of energy. Passive solar a. heating of a house is successful when its windows face the sun, the building is well insulated, and heat can be stored in water tanks, rocks, bricks, or some other suitable material. In a photovoltaic (solar) cell, a wafer of an electron-emitting metal is in contact with another metal that collects the electrons and passes them along into wires in a steady stream. The photovoltaic cells placed on roofs, for example, generate electricity that can be used inside a building or sold to a power company. Scientists are working on improving technologies that allow solar energy to be used to extract hydrogen from water via electrolysis. The hydrogen can then be used as a clean-burning fuel; when it burns, water is produced. Presently, most cars have internal combustion engines that run on gasoline. Automobile manufacturers are working on building vehicles that will be powered by fuel cells, which use hydrogen to produce electricity (Fig. 32.18), and many gasoline–fuel cell hybrid vehicles now exist. The electricity runs a motor that propels the vehicle. Fuel cells are powering buses in Vancouver and Chicago, with more in the development phase. The advantages of a solar-hydrogen revolution would be at least two- fold: (1) The world would no longer be dependent on oil, and (2) environ- mental problems, such as acid rain and smog, would begin to lessen. Minerals Figure 32.18 Solar-hydrogen revolution. Minerals are nonrenewable raw materials in the Earth’s crust that can be b. a. This bus is powered by hydrogen fuel. b. The use of gasoline–fuel mined (extracted) and used by humans. Nonrenewable minerals include cell hybrid vehicles, such as this prototype, will reduce air pollution fossil fuels; nonmetallic raw materials, such as sand, gravel, and phosphate; and dependence on fossil fuels. and metals, such as aluminum, copper, iron, lead, and gold. (a): © LusoEnvironment/Alamy; (b): © Piroschka van de Wouw/EPA/Newscom Nonrenewable resources are subject to depletion—that is, the supply will eventually run out. We can extend our supply of fossil fuels if we conserve our use, recycle metals, and find new reserves. In the United States, huge machines can go as far as removing mountain- tops in order to reach a mineral (Fig. 32.19). The land becomes devoid of vegetation, allowing runoff from rain to wash toxic waste deposits into nearby streams and rivers. Legislation now requires that strip miners restore the land to its original condition, a process that can take years to complete. Other Sources of Pollution Figure 32.19 Modern mining capabilities. Synthetic organic compounds and wastes are also pollutants of concern. Giant mining machines—some as tall as a 20-story building—can remove an enormous amount of the Earth’s crust in one scoop in Synthetic Organic Compounds order to mine for coal or a metal ore. © James P. Blair, National Geographic Creative Synthetic organic compounds are of considerable ecological concern due to their detrimental effects on the health of living organisms, including humans. Synthetic organic compounds play a role in the production of plastics, pesti- cides, herbicides, cosmetics, coatings, solvents, wood preservatives, and hun- dreds of other products. Synthetic organic compounds include halogenated hydrocarbons, compounds in which halogens (chlorine, bromine, fluorine) have replaced some hydrogen atoms. Chlorofluorocarbons (CFCs) are a type of haloge- nated hydrocarbon in which both chlorine and fluorine atoms replace some of the hydrogen atoms. CFCs have brought about a thinning of the Earth’s ozone shield, which protects terrestrial life from the dangerous effects of
642 PART SEVEN Ecology ultraviolet radiation. In most MDCs, legislation has been passed to prevent the production of any more CFCs. Hydrofluorocarbons, which contain no chlorine, are expected to take their place in coolants and other products. The ozone shield is predicted to recover by 2050; in the meantime, many more cases of skin cancer are expected to occur. Other synthetic organic chemicals pose a direct and serious threat to the health of all living organisms. Rachel Carson’s book Silent Spring, published in 1962, made the public aware of the deleterious effects of pesticides. Wastes Every year, the countries of the world discard billions of tons of solid wastes, some on land and some in fresh and marine waters. Solid wastes are visible wastes, some of which are hazardous to our health. Industrial Wastes Industrial wastes are generated during the mining and production of a product. Clean-water and clean-air legislation in the United States in the early 1970s prohibited venting of industrial wastes into the atmo- sphere and flushing them into waterways. Industry turned to land disposal, which was unregulated at the time. The use of deep-well injection, pits with plastic liners, and landfills led to much water pollution and human illness, including cancer. An estimated 5 billion metric tons of highly toxic chemicals were improperly discarded in the United States between 1950 and 1975. The public’s concern was so great that the Environmental Protection Agency (EPA) came into existence. Using an allocation of monies called the Super- fund, the EPA oversees the cleanup of hazardous waste disposal sites in the United States. Connections: Health What is methylmercury, and why is it dangerous? Methylmercury is a molecule in which the element mercury has been bound to a methyl (CH₃) group. Because of this methyl group, methylmercury easily accumulates in the food chain by biological magniication, or the concentration of chemicals in a food chain. Methylmercury is released into the environment by the burning of coal, the min- © Franco Bani/WaterFrame/Getty Images ing of certain metals, and the incineration of medical waste. Methylmercury is a powerful neurotoxin that also inhibits the activity of the immune system. Because of this, the FDA and the EPA recommend that pregnant women and small chil- dren not eat shark, swordish, tileish, or king mackerel and that they limit their consumption of albacore tuna to less than 6 ounces per week. Most states have also posted warnings about eating local ish that have been caught from mercury-contaminated waters. For more information, visit the EPA website, www.epa.gov/waterscience/ish. Among the most commonly found contaminants in industrial wastes are heavy metals (lead, arsenic, cadmium, chromium) and organic compounds (trichloro- ethylene, toluene, benzene, polychlorinated biphenyls [PCBs], and chloro- form). Some of the chemicals used in pesticides, herbicides, plastics, food additives, and personal hygiene products are classified as endocrine disrupters.
These products can affect the endocrine system and interfere with reproduc- CHAPTER 32 Human Impact on the Biosphere 643 tion. In the environment, they occur at a level 1,000 times greater than the hormone levels in human blood. great blue heron sunfish Decomposers are unable to break down these wastes. They enter and re- main in the bodies of organisms because they are not excreted. Therefore, they mayfly nymph become more concentrated as they pass along a food chain, a process termed biological magnification (Fig. 32.20). This effect is most apt to occur in algae aquatic food chains, which have more links than do terrestrial food chains. Humans are one of the final consumers in both types of food chains, and in Figure 32.20 Biological magniication. some areas, human breast milk contains detectable amounts of polychlorinated hydrocarbons, DDT, and PCBs. A poison, such as DDT, that is excreted in relatively small amounts (arrows) becomes maximally concentrated as it passes along a food Sometimes industrial wastes accumulate in the mud in deltas and estuar- chain due to the reduced size of the trophic levels. ies of highly polluted rivers and cause environmental problems if disturbed. Industrial pollution is being addressed in many MDCs, but it usually has low 32.3 CONNECTING THE CONCEPTS priority in LDCs. The human population’s need for Sewage Raw sewage can contribute to oxygen depletion in lakes and rivers. resources is creating problems for Sewage serves as a fertilizer for plants, which can lead to eutrophication; first the world’s ecosystems. there is an algal bloom; then, when the algae use up all the nutrients, they die. Decomposition of dead algae robs the water of oxygen, which can result in a massive fish kill. Also, human feces can contain pathogenic microorganisms that cause cholera, typhoid fever, and dysentery. In regions of LDCs where sewage treatment is practically nonexistent, many children die each year from these diseases. Sewage treatment plants use bacteria to break down organic matter to inorganic nutrients, such as nitrates and phosphates, which then enter surface waters. Check Your Progress 32.3 1. Distinguish between renewable and nonrenewable resources. 2. Explain the causes of deforestation and desertiication, and list environmental problems associated with each. 3. List the harmful efects of modern agricultural practices. 4. Summarize the inluences of the “green revolution.” 5. List four renewable energy sources, and identify a drawback of each. 32.4 Sustainable Societies Learning Outcomes Upon completion of this section, you should be able to 1. Explain why human society is unsustainable in its current form. 2. List some activities that may help make rural societies more sustainable. 3. List some activities that may help make urban societies more sustainable. A sustainable society is able to provide the same goods and services for future generations of humans as it does now while preserving biodiversity.
644 PART SEVEN Ecology non- materials Today’s Society renewable energy The following evidence indicates that, at present, human society is not sustainable (Fig. 32.21a): minimal recycling ∙ A considerable proportion of land, and therefore of natural processing and ecosystems, is being used for human purposes (homes, agri- manufacturing culture, factories, etc.). waste waste products ∙ Agriculture requires large inputs of nonrenewable fossil fuel energy materials energy, fertilizer, and pesticides, which creates pollution. (heat) More fresh water is used in agriculture than in homes. minimal recycling ∙ At least half the agricultural yield in the United States goes a. Human society at present toward feeding animals. According to the 10-to-1 rule of thumb, it takes 10 pounds of grain to grow 1 pound of meat. renewable materials Therefore, it is inefficient for citizens in MDCs to eat as much energy meat as they do. Also, animal sewage pollutes water. processing and maximal recycling ∙ Even though fresh water is a renewable resource, we are manufacturing running out of the available supply. waste waste products ∙ Our society uses primarily nonrenewable fossil fuel energy, energy materials which leads to acid precipitation, smog, and various other (heat) pollutants entering the ecosystems. maximal recycling ∙ Minerals are nonrenewable resources, and the mining, pro- cessing, and use of minerals are responsible for much envi- b. Sustainable society ronmental pollution. Figure 32.21 Current human society versus a sustainable Characteristics of a Sustainable Society society. A natural ecosystem can offer clues as to what a sustainable human society would be like. A natural ecosystem is characterized by the use a. Our “throw-away” society is characterized by high input of energy of renewable solar energy, the cycling of materials through the various and raw material, large output of waste materials and energy in the populations, and the return of nutrients and energy to the producers. If form of heat, and minimal recycling (white arrows). b. A sustainable we want to develop a sustainable society, we should also use renewable society is characterized by the use of only renewable energy energy sources and recycle materials (Fig. 32.21b). These principles sources, the reuse of heat and waste materials, and maximal can be applied to both rural and urban areas. recycling of products (blue arrows). Rural Sustainability (a): © Kent Knudson/PhotoLink/Getty RF; (b): © Scenics of America/PhotoLink/ Getty RF In rural areas, we should put the emphasis on preservation. We should preserve ecosystems, including terrestrial ecosystems—such as forests and prairies—and aquatic ecosystems—both freshwater ones and brackish ones along the coast. We should also preserve agricultural land, groves of fruit trees, and other areas that provide us with renewable resources. It is imperative that we take all possible steps to preserve what remains of our topsoil and replant areas with native grasses, as necessary. Native grasses stabilize the soil and rebuild soil nutrients while serving as a source of renew- able biofuel. Trees can be planted to break the wind and protect the soil from erosion while providing a product. Creative solutions to today’s ecological problems are very much needed. Here are some other methods we can use to make rural areas more sustainable: ∙ Plant cover crops, which often are a mixture of legumes and grasses, to stabilize the soil between rows of cash crops or between seasonal plant- ings of cash crops. ∙ Practice multiuse, or polyculture, farming (see Fig. 32.13a) by planting a variety of crops and use a variety of farming techniques to increase the amount of organic matter in the soil.
∙ Replenish soil nutrients through composting, organic gardening, or other CHAPTER 32 Human Impact on the Biosphere 645 self-renewable methods. Figure 32.22 Rural sustainability. ∙ Use low-flow or trickle irrigation, retention ponds, and contour farming (see Fig. 32.13b) to conserve water. Trees planted by a farmer to break the wind and prevent soil erosion can also have other purposes, such as supplying fruits and nuts. ∙ Increase the planting of cultivars (plants propagated vegetatively) that Source: USDA Natural Resources Conservation Service/Erwin Cole, are resistant to blight, rust, insect damage, salt, drought, and encroach- photographer ment by noxious weeds. Figure 32.23 Urban sustainability. ∙ Use precision farming (PF) techniques that rely on accumulated knowl- edge to reduce habitat destruction while improving crop yields. Green roofs are ecologically sound and can be visually beautiful. © Diane Cook and Len Jenshel/Getty Images ∙ Use integrated pest management (IPM), which encourages the growth of competitive beneficial insects and uses biological controls to reduce the abundance of a pest (see Fig. 32.13c). ∙ Plant a variety of species, including native plants, to reduce our depen- dence on traditional crops. ∙ Plant multipurpose trees—trees with the ability to provide numerous products and perform a variety of functions, in addition to serving as windbreaks (Fig. 32.22). Mature trees can provide many types of prod- ucts: Mature rubber trees provide rubber, and tagua nuts are an excellent substitute for ivory, for example. ∙ Maintain and restore wetlands, especially in hurricane- or tsunami-prone areas. Protect deltas from storm damage. By protecting wetlands, we protect the spawning grounds for many valuable fish species. ∙ Use renewable forms of energy, such as wind, hydropower, and solar energy. ∙ Support local farmers, fishermen, and feed stores by buying food prod- ucts produced locally. Urban Sustainability More and more people are moving to cities. Much thought needs to be given to serving the needs of new arrivals without overexpanding the city. Here are some methods by which we can make cities more sustainable: ∙ Create energy-efficient transportation systems to efficiently move people about. ∙ Use solar or geothermal energy to heat buildings; cool them with an air- conditioning system that uses seawater; in general, use conservation methods to regulate the temperature of buildings. ∙ Utilize green roofs—a wild garden of grasses, herbs, and vegetables on the tops of buildings—to assist in temperature control, supply food, reduce the amount of rainwater runoff, and create visual appeal (Fig. 32.23). ∙ Improve storm-water management by using sediment traps for storm drains, artificial wetlands, and holding ponds. Increase the use of porous surfaces for walking paths, parking lots, and roads. These surfaces reflect less heat while soaking up rainwater runoff. ∙ Instead of traditional grasses, plant native species that attract bees and butterflies and require less water and fertilizers. ∙ Create greenbelts that suit the particular urban setting. Include plentiful walking and bicycle paths. ∙ Revitalize old sections of a city before developing new sections. ∙ Use lighting fixtures that hug the walls or ground and send light down; control noise levels by designing quiet motors. ∙ Promote sustainability by encouraging the recycling of business equip- ment; use low-maintenance building materials, rather than wood.
646 PART SEVEN Ecology 32.4 CONNECTING THE CONCEPTS Connections: Environment Current human society is not What are some simple things you can do to conserve energy sustainable, however, progress and/or water and help solve environmental problems, such as is being made to increase climate change? sustainability. The following are a few things you can do: Check Your Progress 32.4 • Change the lightbulbs in your home to com- 1. List the characteristics of a sustainable society. pact luorescent bulbs. They use 75–80% less 2. Summarize the steps that could increase rural electricity than incandescent bulbs. sustainability. • Walk, ride your bike, carpool, or use mass 3. Summarize the steps that could increase urban transit. It will save you a lot of money, too! sustainability. • Get cloth or mesh bags for groceries and other purchases. Plastic bags may take 10–20 years to degrade. They’re also dangerous to wildlife if mistaken for food and consumed. • Turn of the water while you brush your teeth. © Mike Kemp/Getty RF If you don’t inish a bottle of water, use it to water your plants. In dry climates, plant native plants that won’t require frequent watering. STUDY TOOLS http://connect.mheducation.com Maximize your study time with McGraw-Hill SmartBook®, the irst adaptive textbook. SUMMARIZE ∙ Waste disposal (through the action of decomposers and the ability of natural communities to purify water and take up pollutants) Human actions are placing tremendous stress on the Earth’s natural resources. Human-induced climate change is going to decrease Earth’s ∙ Fresh water provision through the water biogeochemical cycle biodiversity. Sustainable options are available if people are willing to make ∙ Prevention of soil erosion, which occurs naturally in intact the necessary changes. ecosystems 32.1 Conservation biology seeks to balance the needs of humans with the ∙ Climate regulation (plants take up carbon dioxide) 32.2 needs of the rest of the species on Earth. ∙ Ecotourism (human enjoyment of a beautiful ecosystem) 32.3 The Earth’s biodiversity has tremendous value to humans, but it is under 32.3 Resources and Environmental Impact 32.4 stress. Five resources are maximally used by humans: The human population’s need for resources is creating problems for the world’s ecosystems. Human population Current human society is not sustainable, however, progress is being made to increase sustainability. 32.1 Conservation Biology land water food energy minerals Conservation biology is a field of biology that is concerned with conserving Resources are either nonrenewable or renewable. Nonrenewable the Earth’s natural resources for this and future generations. resources, such as fossil fuels and minerals, are limited in supply. Renewable resources, such as solar energy and hydroelectric power, 32.2 Biodiversity are not limited in supply. Biodiversity is the variety of life on Earth. The majority of species are Land located in a relatively small number of biodiversity hotspots. Biodiversity Human activities, such as habitation, farming, and mining, contribute to has both direct values and indirect values. erosion, pollution, desertification, deforestation, and loss of biodiversity. Direct Values of Biodiversity Water The direct values of biodiversity are: Industry and agriculture use most of the freshwater supply. Water supplies are increased by damming rivers and drawing from aquifers. As aquifers are ∙ Medicinal value (medicines derived from living organisms) depleted, subsidence, sinkhole formation, and saltwater intrusion can ∙ Agricultural value (crops derived from wild plants) occur. Irrigation of farmlands consumes large amounts of water and can lead ∙ Biological pest controls and animal pollinators to salinization. If used by industries, water conservation methods could cut ∙ Consumptive use values (food production) world water consumption by half. Indirect Values of Biodiversity Biodiversity in ecosystems contributes to: ∙ The functioning of biogeochemical cycles (water, carbon, nitrogen, phosphorus, and others)
Food CHAPTER 32 Human Impact on the Biosphere 647 Food comes from growing crops, raising animals, and fishing. 32.4 Sustainable Societies ∙ Modern farming methods increase the food supply, but some methods harm the land, pollute the water, and consume fossil fuels excessively. A sustainable society would use only renewable energy sources, reuse heat and waste materials, and recycle almost everything. It would also provide the ∙ Transgenic plants can increase the food supply and reduce the need for same goods and services presently provided and would preserve biodiversity. chemicals. ASSESS ∙ Raising livestock contributes to water pollution and uses fossil fuel energy. ∙ The increased number and high efficiency of fishing boats have caused Testing Yourself the world fish catch to decline. Choose the best answer for each question. Energy Most of the world’s energy is supplied by the burning of fossil fuels, a 32.1 Conservation Biology nonrenewable resource, which causes pollutants and greenhouse gases to enter the air. Renewable energy sources include wind power, hydropower, 1. Which subfield of biology helps support conservation biology? and geothermal energy. Photovoltaic (solar) cells are being used to access a. ecology solar energy. b. forestry Minerals c. genetics Minerals are a nonrenewable resource that can be mined. These raw materials d. evolutionary biology include sand, gravel, phosphate, and metals. The act of mining causes e. All of these are correct. destruction of the land by erosion, loss of vegetation, and toxic runoff into bodies of water. Land ruined by mining can take many years to recover. 2. What is the main goal of conservation biology? Synthetic Organic Compounds a. conserving natural resources for current and future generations Compounds such as chlorofluorocarbons (CFCs) are detrimental to the b. increasing agricultural yields ozone shield and to the health of living organisms, including humans. c. decreasing human mortality Wastes d. identifying species that provide a monetary value to humans Raw sewage and industrial wastes can pollute land and bodies of water. Some e. All of these are correct. industrial wastes cause biological magnification, a process by which toxins become more concentrated as they are passed upward in a food chain. 32.2 Biodiversity great blue heron 3. Which of the following is an indirect value of biodiversity? a. participation in biogeochemical cycles sunfish b. participation in waste disposal c. provision of fresh water mayfly nymph d. prevention of soil erosion e. All of these are correct. algae 4. The preservation of ecosystems indirectly provides fresh water because a. trees produce water as a result of photosynthesis. b. animals excrete water-based products. c. forests soak up water and release it slowly. d. ecosystems promote the growth of bacteria that release water into the environment. e. plants trap moisture with their leaves. 32.3 Resources and Environmental Impact 5. Desertification typically happens because a. deserts naturally expand in size. b. humans allow overgrazing. c. desert animals wander into adjacent areas for food. d. humans tap into limited water supplies for their water needs in the nearby desert. 6. Soils in tropical rain forests are typically nutrient-poor because a. they receive more water than other ecosystems. b. they are sandy. c. nitrogen-fixing bacteria are absent. d. nutrients are tied up in vegetation. 7. Most of the fresh water in the world is used for a. drinking. b. supporting industry. c. irrigating crops. d. cooking. e. bathing.
648 PART SEVEN Ecology 8. A major negative effect of the dumping of raw sewage into lakes and ENGAGE rivers is a. oxygen depletion. Thinking Critically b. the buildup of carbon. c. a reduction of light penetration into the water. 1. In 1993, the U.S. Fish and Wildlife Service established Emiquon d. an increase in populations of small fish. National Wildlife Refuge to restore and protect wetland habitats. The Illinois and Spoon River confluence was restored to its original 9. Which of the following will help conserve fresh water? floodplain. In order to achieve this, hundreds of acres of farmland were a. saltwater intrusion flooded. What might be the positive and negative environmental b. drought-tolerant crops impacts of flooding the confluence of these two rivers? What direct c. increased irrigation and indirect benefits could a project like this provide for the residents d. use of water contained in aquifers of central Illinois? 10. The “green revolution” resulted from the development of 2. Every time a species becomes extinct, we lose a potential source of a. high-responder wheat and rice varieties. medicine for human illness. Since we do not know which species are b. effective irrigation systems. likely to provide valuable medicines, it is difficult to know where to c. transgenic crop plants. focus conservation efforts. If you were in charge of determining high d. crops designed for animal feed. priorities for species conservation in a country, with the goal of identifying plants with medicinal value, what factors would you 32.4 Sustainable Societies consider in making your decisions? 11. Show how the following diagram must change in order to develop a 3. Knowing that organisms are closely adapted to their environment, why sustainable society. might global climate change cause the extinction even of mammals living in the tropics? non- materials renewable 4. Visit footprint.wwf.org.uk to determine the size of your ecological energy footprint, and then discuss ways you can reduce that value. minimal recycling processing and manufacturing waste waste products energy materials (heat) minimal recycling 12. Which of the following would help make both urban and rural areas more sustainable? a. plant multipurpose trees b. use low-flow irrigation to conserve water c. use more solar energy d. plant cover crops e. use green roofs
Appendix A Periodic Table of the Elements & The Metric System Periodic Table of the Elements APPENDIX A Atomic number Atomic mass CSolid Metalloids Atomic symbol 11 Other nonmetals H Nonmetals Halogens Noble gases Group Ia hydrogen HgLiquid Alkali metals VIIIa Alkaline earth metals 11 Lanthanoids 24 Actinoids H He hydrogen IIa HGas IIIa IVa Va VIa VIIa helium 37 49 Metals 5 11 6 12 7 14 8 16 9 19 10 20 Li Be B CN O F Ne lithium beryllium RfUnknown Transition metals boron carbon nitrogen oxygen fluorine neon Post-transition metals 11 23 12 24 13 27 14 28 15 31 16 32 17 35 18 40 Na Mg Al Si PS Cl Ar sodium magnesium IIIb IVb Vb VIb VIIb VIIIb Ib IIb aluminum silicon phosphorus sulfur chlorine argon 19 39 20 40 21 45 22 48 23 51 24 52 25 55 26 56 27 59 28 59 29 64 30 65 31 70 32 73 33 75 34 79 35 80 36 84 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 37 85 38 88 39 89 40 91 41 93 42 96 43 98 44 101 45 101 46 106 47 108 48 112 49 115 50 119 51 122 52 128 53 127 54 131 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 55 133 56 137 57 139 72 178 73 181 74 184 75 186 76 190 77 192 78 195 79 197 80 201 81 204 82 207 83 209 84 210 85 210 86 222 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn cesium barium lanthanum hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thalium lead bismuth polonium astatine radon 87 223 88 226 89 227 104 261 105 260 106 263 107 261 108 265 109 266 110 281 111 272 112 285 113 284 114 289 115 288 116 293 117 294 118 294 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium actinium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicum ununtrium flerovium ununpentium livermorium ununseptium ununoctium 58 140 59 141 60 144 61 147 62 150 63 152 64 157 65 159 66 163 67 165 68 167 69 169 70 173 71 175 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu cerium praseodymium n e o d y m i u m p r o m e t h i u m s a m a r i u m europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 90 232 91 231 92 238 93 237 94 242 95 243 96 247 97 247 98 249 99 254 100 253 101 256 102 254 103 257 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium n o b e l i u m lawrencium The names of elements 113, 115, 117 and 118 are pending approval by the IUPAC. A-1
A-2 APPENDIX A Periodic Table of the Elements & The Metric System The Metric System
Appendix B Answer Key CHAPTER 1 BioNow its special properties come from its ability to form APPENDIX AB hydrogen bonds. (2.3) 1. Acids in solution release Check Your Progress Our bodies continuously maintain a stable internal hydrogen ions creating solutions with higher hydrogen environment that is organized through the processes of ion concentrations. Bases in solution either take (1.1) 1. The basic characteristics of life are: living homeostasis. We respond to our environment through up hydrogen ions or release hydroxide ions. Basic organisms are organized, they acquire materials and our senses and motor skills. We consume nutrients and solutions have lower hydrogen ion concentrations. energy, they maintain an internal environment, they gather materials so that we can adapt to our changing 2. The pH scale indicates the number of hydrogen ions respond to stimuli, they can reproduce and develop, environment and be fit to develop and reproduce. in a solution. A value below 7 indicates an acid and and they can adapt to their environment. 2. From a value above 7 indicates a base. 3. Buffers in fluids smallest to largest the levels of biological organization Thinking Critically of the body resist pH changes by taking up excess are: small molecule, large molecule, cells, tissues, hydrogen or hydroxide ions. organs, organ systems, complete organism. 3. Energy 1. Domain Archaea gave rise to Eukarya. Kingdom flow and chemical cycling occur within organisms Protista gave rise to plants, animals, and fungi. Testing Yourself and in ecosystems. Each cell or organism must take in 2. Model organisms, perhaps mice, which exhibits energy and materials including nutrients. Producers the type of cancer being studied are identified. A 1. a; 2. c; 3. c; 4. a; 5. b; 6. a; 7. b; 8. c; 9. b; 10. c; capture energy and produce food by photosynthesis. hypothesis that the drug is effective against cancer 11. c; 12. a The chemicals in this food are cycled through food is formed. The prediction is made that the drug chains and eventually deposited or released upon administered to the mice will remove the cancer from BioNow death when they become available again to producers. them.The mice are divided into groups; a control group Energy flows from the sun through plants and animals. receiving a placebo, and test group(s) receiving levels All the properties of water are important to living It eventually dissipates as heat into the atmosphere. of the new drug. The drug or placebo is administered organisms. It is a great solvent for biomolecules. Its (1.2) 1. Species, genus, family, order, class, phylum, during the experiment. The mice are monitored for high heat capacity helps to maintain a constant internal kingdom, domain. 2. Natural selection is the process the disappearance of cancer. The data collected are temperature. Its properties of cohesion and adhesion in which populations adapt to pressures imposed analyzed and conclusions are made about the drug's help in moving water through a vascular system. Its by their environments. Over time those individuals effectiveness against cancer. The experiment is high heat of vaporization helps in cooling by sweating having adaptations that make them well suited to their repeated as needed to test any revised hypotheses and and in maintaining hydration. Lakes do not freeze solid environment will live and produce more offspring than the results are published for review by others. 3. The killing organisms because ice is less dense than water. others. Natural selection is an important biological hypothesis would be that the potential life-form is alive. concept that explains population changes, like those The prediction is that it exhibits the characteristics of Thinking Critically seen in antibiotic resistant bacteria. 3. Descent with behavior and adaptation found in living organisms. An modification means that descent occurs from common experiment is constructed to observe or test if the life- 1. Surface tension produced by hydrogen bonding ancestors to different species, each of which is adapted form can acquire materials and nutrients, respond to its keeps the surface of the water smooth and continuous. to a particular environment. Both common ancestry environment, or reproduce and develop and in so doing, Drops of water cling to your skin due to the and diversity are important to the study of evolution. adapt to its environment over generations. adhesiveness of water. When this water evaporates (1.3) 1. Making observations of our environment is it cools your skin because of water’s high heat of the first step in the scientific method. Constructing a CHAPTER 2 vaporization. A lot of body heat is removed as water hypothesis based on existing knowledge to explain the evaporates. 2. Silicon, with one extra shell, is too big observation is next. Making a prediction based on the Check Your Progress to form the same varied molecules as carbon. hypothesis that can be tested by an experiment follows. 3. The chemicals in antacids act as buffers absorbing The results from the experiment either support the (2.1) 1. Nucleus with protons (+) and neutrons (neutral) excess hydrogen ions in the stomach. 4. The acids hypothesis or not. Further testing and data analysis surrounded by shells of electrons (–). in acid precipitation can change the pH of the water result in a conclusion being made. Ultimately, with 2. Isotopes are atoms of the same element that differ in environments of an ecosystem if they exceed the repeated confirmation through experimentation, a the number of neutrons. They have the same number of buffering capacity present there. Altered pH levels scientific theory can be constructed. 2. Including protons but have different mass numbers. Radioactive affect the homeostatic processes of the environment, controls in an experimental design is essential to isotopes are unstable and emit radiation. They can be and the organisms within it, causing damage. determine if the experimental variable can explain the used in PET scans and to kill cancer cells. 3. Both are hypothesis. 3. Publishing the results of experiments types of chemical bonds. Covalent bonds share pairs of CHAPTER 3 in journals allows for critical review by others of electrons; ionic bonds have one atom giving an electron the hypothesis, predictions, experimental design, to another atom. 4. If an atom has two or more shells, Check Your Progress and data. (1.4) 1. Science is a systematic way of the outer shell (the valence shell) is most stable when it acquiring knowledge. Technology is the application of has eight electrons. Elements with incomplete valence (3.1) 1. Organic molecules which make up cells scientific knowledge for human benefit. 2. Ecosystem shells are more reactive. 5. Reactants are molecules and organisms contain carbon and hydrogen degradation, emerging diseases, and climate change that participate in a reaction. Products are molecules atoms. Inorganic molecules, such as water and are occurring at accelerated rates due to human formed by reactions. (2.2) 1. Water molecules are polar salt, do not contain a combination of carbon and influences on the world’s ecosystems. Biodiversity is with positive hydrogen atoms in one molecule being hydrogen. 2. Carbon is small and can bond with up being reduced and this threatens all species. attracted to the negative oxygen atoms in the other. to four other molecules. The C—C bond is stable. This is a hydrogen bond. The properties of water are 3. The functional group of an organic molecule Testing Yourself related to its polarity and its ability to form hydrogen determines the reactivity and chemical properties of bonds. 2. Water has unique properties. It is a solvent, the molecule. (3.2) 1. Monosaccharides—glucose; 1. c; 2. b; 3. c; 4. d; 5. c; 6. c; 7. b; 8. b; 9. c; 10. b; its molecules are adhesive and cohesive, it has a high disaccharides—maltose; polysaccharides—glycogen. 11. d; 12. d surface tension, it has a high heat capacity, and it is Starch is a polysaccharide used for energy storage. less dense than ice. 3. Water is a polar molecule and Cellulose is a polysaccharide that provides structural components to cells. 2. Fats and oils—olive oil as an energy source; phospholipids—primary component B-1
B-2 APPENDIX B Answer Key of plasma membrane; steroids—cholesterol as a Eukaryotic cells have a membrane-bound nucleus BioNow component of plasma membrane and precursor to that houses the DNA. 3. Nucleoid—region of the sex steroids. 3. Structural proteins provide support. cytoplasm that stores DNA in prokaryotes; Cell A larger surface to volume ratio means that there Enzymes are proteins that function as catalysts in wall—maintains the shape of the cell providing is relatively more surface area through which the metabolism. There are channel and carrier proteins in strength; Ribosomes—site of protein synthesis; molecules involved in metabolism can pass. Oxygen, the plasma membrane. Antibodies are proteins which Flagella—rotating filament that propels the cell. water, and nutrients can move into the cell more provide defense. Some hormones which function (4.4) 1. Nucleus: nuclear envelope—double rapidly and wastes and carbon dioxide can move out in regulation are proteins. 4. Primary—sequence of membrane phospholipid that separates nucleus more quickly. The increased amounts and of exchange amino acids; secondary—alpha helix and pleated from cytoplasm; Nuclear pore—openings in the could lead to increased rates of metabolism. sheets; tertiary—globular shape; quaternary—more nuclear envelope that allow the cell nucleus to than one polypeptide 5. Nucleic acids are polymers communicate with the cytoplasm; Chromatin— Thinking Critically of nucleotides each of which has a phosphate group, network of DNA and proteins that contains genetic a 5-carbon sugar, and a nitrogen-containing base. information; Ribosomes: composed of a small and 1. The smaller hummingbird egg with its greater 6. DNA, a nucleic acid, encodes the information large subunit that together use the information of surface to volume ratio would be expected to have that determines the sequence of amino acids in a the RNA from the nucleus to synthesize proteins. the higher metabolic rate. 2. Without mitochondria a polypeptide. RNA, another nucleic acid, functions in 2. Nuclear envelope—houses DNA; Rough cell could not produce ATP from nutrients aerobically the process of polypeptide synthesis. endoplasmic membrane—contains ribosomes but would instead have to rely only on glycolysis and forms transport vesicles that take proteins which is less efficient, for ATP production. Giardia Testing Yourself to other parts of the cell; Smooth endoplasmic may have increased its ability to metabolize nutrients reticulum—synthesizes tissue specific lipids; Golgi using glycolysis or have adapted to a lower metabolic 1. c; 2. d; 3. b; 4. b; 5. a; 6. a; 7. a; 8. a; 9. c; 10. b; apparatus—functions as a transfer station which rate. 3. A cell line that already is involved in the 11. d; 12. b; 13. d; 14. c; 15. a; 16. a; 17. c; 18. d receives transport vesicles from the endoplasmic secretion of proteins should be selected. This would reticulum, modifies the molecules within the be a cell line that efficiently produces proteins that Thinking Critically vesicles, packages modified molecules, and sends are enclosed in vesicles which are transported to them out in outgoing transport vesicles; vesicles like the plasma membrane where the vesicles fuse and 1. The labeling of HDL as good and LDL as bad is lysozymes which digest molecules. 3. Contractile release their contents to the outside. The genes for the an easy way to understand the different functions of vacuoles rid the cell of excess water; Digestive production of the protein of interest would need to be the lipoproteins. HDL helps to move cholesterol from vacuoles break down nutrients; Storage vacuoles inserted into the genome of the cell and these genes tissues to the liver which is good and LDL moves in plants can hold water, sugars, salts, pigments, or would need to be activated. cholesterol to the tissues where it can possibly form toxic chemicals; Adipocytes in animals store lipids. plaques which is bad. However some cholesterol Without vacuoles cells would not be able to regulate CHAPTER 5 needs to be in the tissues and in the liver for proper water and ion content, break down certain nutrients, metabolism. So it is the opposition of the functions or store compounds. 4. Chloroplasts contain Check Your Progress of HDL and LDL that keeps cholesterol levels in the pigments that capture solar energy which is used to tissues and liver in balance. 2. A protein’s ability to synthesize carbohydrates. Mitochondria break down (5.1) 1. Potential energy is stored energy; kinetic function correctly is dependent upon its shape. In this carbohydrates to produce ATP. Chloroplasts are larger energy is energy of motion. Pulling back on an arrow case, the amino acid with the polar R group may interact and are found in plants and algae. Mitochondria in a bow is potential energy. When the arrow is shot with other polar R groups within the protein and change are smaller and are in all eukaryotic cells. Both from the bow, it turns into kinetic energy. 2. First the enzyme’s shape and its ability to function. are bound by a double membrane. 5. Cytoskeleton Law—Energy cannot be created or destroyed but it 3. Mutations in DNA that change the sequence of amino proteins maintain the shape of the cell and work with can be changed from one form to another. Second acids occur over time. The longer the time since two motor proteins to create movement. The cytoskeleton Law—Energy cannot be changed from one form to species diverged, the greater the chance for mutations contains microtubules, intermediate filaments, and another without loss of usable energy. 3. Cells carry to occur. Measuring the differences in the amino acid actin filaments. The motor protein myosin interacts out many energy requiring processes and reactions to sequences of the protein in two species can be used as a with actin filaments to create amoeboid movement maintain their organization while the entropy of the clock to determine how long ago they diverged. and muscle contraction. The motor proteins kinesin universe increases. (5.2) 1. ATP is produced through and dynein transport vesicles along the microtubules. cellular respiration. ATP is unstable so it cannot be CHAPTER 4 (4.5) 1. Cell walls provide strength to the cell stored. 2. Myosin combines with ATP prior to its structure as well as defining the cell’s shape. 2. The breakdown. Release of ADP + causes myosin Check Your Progress extracellular matrix is a network outside the cell to change position and pull on the actin filament. of fibrous proteins and polysaccharides produced 3. During cellular respiration in the mitochondria, (4.1) 1. Most cells are too small to be seen with by a cell. Collagen and elastin are proteins that are carbohydrates are broken down releasing energy the naked eye. Microscopes allow us to see these common to the matrix which can vary widely in that is used in the formation of ATP. Oxygen is used cells. 2. frog egg—light; animal cell—light or its composition and rigidity. 3. Adhesion junctions and carbon dioxide and water are released. During electron; amino acid—electron; chloroplast—light are formed when internal cytoplasmic plaques are photosynthesis in the chloroplasts solar energy or electron; plant cell—light or electron. 3. Enough joined by intercellular filaments. They are sturdy is captured and used to synthesize carbohydrates surface area of the cell is needed for the adequate and flexible structures that hold cells together. from carbon dioxide and water. Oxygen is released. exchange of gases, nutrients, and wastes. Tight junctions are created when plasma membrane (5.3) 1. The reactions in a pathway each produce a (4.2) 1. Phospholipid bilayer including cholesterol proteins attach to those of another cell producing a product that is usable in one or more other ways. The molecules and embedded proteins. 2. The proteins barrier between the cells. Gap junctions form when reactions of a metabolic pathway allow energy to embedded in the bilayer have a mosaic pattern identical membrane channels join between two cells. be used or generated in increments in an organized and the entire bilayer is semi-fluid with the The channels allow small molecules to pass between way. 2. The binding of the substrate to an enzyme molecules being able to move within the structure. the cells and they add strength to the cell. results in a small change in shape of the molecule- 3. Channel—allow passage of certain molecules; substrate complex. This facilitates the reaction to Transport—passage of ions and molecules requiring Testing Yourself produce product(s). 3. It ensures that the enzyme is energy; Cell recognition—glycoproteins which help active only when product levels are low and more to distinguish foreign from own cells; Receptor— 1. a; 2. b; 3. b; 4. d; 5. d; 6. c; 7. a; 8. a. vesicle; product is needed. (5.4) 1. With diffusion, facilitated bind signal molecules; Enzymatic—participate in b. centrioles; c. mitochondrion; d. rough endoplasmic diffusion, and osmosis substances move from an metabolic reactions; Junction—form cell junctions reticulum; e. smooth endoplasmic reticulum; area of higher concentration to an area of lower between cells. (4.3) 1. Plasma membrane, semifluid f. lysosome; g. Golgi apparatus; h. nucleus; 9. a; concentration and no energy is required. Channel interior called the cytoplasm, genetic material 10. c; 11. c; 12. a; 13. c; 14. d; 15. e proteins function in facilitated diffusion. During (DNA). 2. Prokaryotic cells store their DNA in osmosis water diffuses across a semipermeable a region of the cytoplasm called the nucleoid. membrane. 2. In hypotonic environments cells gain
APPENDIX B Answer Key B-3 water; in isotonic environments there is no net gain or their reaction centers. In PS II the absorption of solar the technology for breaking down cellulose can be loss of water; in hypertonic environments cells lose energy results in electrons being activated and passed improved. water. 3. Active transport moves molecules or ions on to an electron-acceptor molecule in an electron across the plasma membrane collecting or absorbing transport chain. Replacement electrons are supplied by CHAPTER 7 molecules against their concentration gradients. This the splitting of water. In PS I electrons are activated is a mechanism for collecting molecules on one side by the absorption of solar energy and passed down Check Your Progress of a membrane. 4. Exocytosis transports materials out an electron transport chain to an NADP+ molecule, of a cell; endocytosis transports materials into the cell; producing NADPH. 3. Electrons are removed from (7.1) 1. Cellular respiration provides the energy in phagocytosis transports large materials such as food water as it is split by PS II. They are passed from PS II the form of ATP that is needed for cellular activities. into the cell; pinocytosis transports liquid and small to PS I through an electron transport chain. Electrons 2. During cellular respiration glucose is oxidized to particles into the cell; receptor-mediated endocytosis from PSI are transferred to NADP+ as it becomes form CO2, O2 is reduced to form H2O, and energy forms a vesicle around molecules and their receptors. NADPH. 4. The splitting of water supplies replacement is produced. This is the reverse of the reaction for electrons to the reaction center in PS II. (6.3) 1. The photosynthesis. 3. Glycolysis—breakdown of glucose Testing Yourself Calvin cycle uses the energy from the light reactions to to 2 molecules of pyruvate in the cytoplasm; prep fix CO2, reduce CO2, and regenerate RuBP. It generates reaction—pyruvate is broken down to a 2-carbon 1. d; 2. b; 3. a; 4. d; 5. d; 6. c; 7. c; 8. b; 9. a,b,c; 10. d; molecules of glyceraldehyde 3-phosphate which acetyl group carried by CoA in the matrix of the 11. c; 12. b,d; 13. e; 14. d; 15. c plants use to make glucose and other biomolecules. mitochondria with the production of CO2 and NADH; 2. The ATP and NADPH used in the Calvin cycle are citric acid cycle—in the matrix of the mitochondria BioNow generated by the light reactions. 3. Plants can use G3P oxidation of molecules occurs, NADH and FADH2 to make all the molecules they need including lipids, are produced, and CO2 is released; electron transport 1. The cells in the potato will gain water or lose water glucose, sucrose, starch, and cellulose. (6.4) 1. In C3 chain—electrons are passed down a series of carrier by diffusion depending on whether the environment plants carbon dioxide is taken up by the Calvin cycle molecules in the cristae of the mitochondria, NADH is hypotonic or hypertonic. The cells will gain water directly into the mesophyll cells and the first detectable and FADH2 give up electrons, energy is captured as faster the more hypotonic the solution is or lose water molecule is a C3 molecule. In C4 plants such as corn, ATP, O2 accepts electrons to become H2O. faster if the water is more hypertonic. 2. Energy was carbon dioxide fixation results in C4 molecules in the (7.2) 1. Glycolysis is the first step in cellular transferred from the apple to the person, to his cells to mesophyll cells. The C4 molecule releases carbon respiration. It occurs in the cytoplasm of the cell produce ATP which was used by the muscles to power dioxide to the Calvin cycle in the bundle sheath cells. and requires no oxygen. Alternatively, the citric acid the bike which converted the energy to electrical 2. In C4 plants the mesophyll cells are exposed to cycle and the electron transport chain occur within energy which was stored in the battery. At each step carbon dioxide. The bundle sheath cells, where the the mitochondria. The electron transport chain energy was transferred and some lost as heat, but no Calvin cycle occurs, are not. 3. CAM plants are better requires oxygen. Pyruvate, produced by glycolysis, energy was created or destroyed. able to conserve water and live in hot, arid regions. feeds into the citric acid cycle. 2. During the energy- investment step, the breakdown of ATP provides the Thinking Critically Testing Yourself phosphate groups that activate substrates. During the energy-harvesting steps, NADH and ATP are 1. Knowing the shape of the active site of an enzyme 1. c; 2. a; 3. d; 4. a; 5. a; 6. d; 7. b; 8. d; 9. c; 10. b; produced. 3. 2 ATP molecules per glucose molecule. would allow one to design a substrate (a drug in this 11. c (7.3) 1. Fermentation which does not require oxygen case) which fits less well or better at the active site. consists of glycolysis followed by a reduction of The better the fit the more efficient the metabolic BioNow pyruvate by NADH to produce lactate or ethanol and pathway. The worse the fit the pathway would be CO2. It occurs outside of the mitochondria. Cellular slowed down. If the drug could compete with the Wavelengths of light in the yellow and green range are respiration uses oxygen, occurs in mitochondria, usual substrate in binding to the enzyme then you not used in photosynthesis. Instead they are reflected and results in a higher yield of ATP. 2. During would have a mechanism to regulate the speed of giving plants their color. Blue and violet wavelengths lactate fermentation pyruvate is reduced by NADH, the reaction in the pathway. 2. A normal channel as one end of the visible light spectrum and orange producing NAD+ which is recycled back to glycolysis protein allows chloride to leave the cells. When and red wavelengths at the other end of the spectrum to accept more H+. This keeps glycolysis going, chloride leaves, water follows by osmosis, keeping are absorbed and used in photosynthesis. supplying some ATP. 3. Humans produce lactate; the outer surfaces hydrated. Since the defective cystic yeast produces ethyl alcohol and carbon dioxide. fibrosis chloride channel does not allow chloride Thinking Critically (7.4) 1. The preparatory reaction produces a substrate to leave the cell, water remains inside, and the cell that can enter the citric acid cycle. The citric acid surface becomes covered with a thick mucus. 3. The 1. The alga was producing O2 wherever, along cycle generates CO2, NADH, FADH2, and ATP at the composition of the archaeal plasma membrane is its length, its chlorophyll was able to absorb substrate level. The electron transport chain passes different from that of bacteria and eukaryotes. It is the wavelength of light energy it could use in electrons along a series of carriers and captures energy more resistant to disruption from heat. In addition, photosynthesis. The bacteria were congregated that is used in the production of ATP. 2. Oxygen is the archaeal enzymes have evolved to function at higher wherever this O2 was produced and were using it final electron acceptor of the electron transport chain. temperatures without being denatured. for cellular respiration. 2. Artificial leaves would It becomes reduced to form water. 3. Preparatory need to have a large surface area for absorbing solar reactions—pyruvate is oxidized and CO2 is given off, CHAPTER 6 energy and they would need to be thin for efficient NAD+ accepts a H+ to make NADH, a C2 acetyl group gas exchange. They would need a vascular system for is made and attached to CoA; Citric acid cycle—the Check Your Progress the transport of water to the leaf and nutrients away. acetyl group is oxidized, CO2 is released, NAD+ and Within the leaf there would need to be a surface for FAD accept H+ producing NADH and FADH2, ATP (6.1) 1. The stroma of a chloroplast is a fluid-filled housing the pigments and across which the gradients is produced at the substrate level; Electron transport area surrounded by a double membrane. Within the of hydrogen ions used in ATP production are created. chain—electrons are passed along a series of carriers, stroma are membrane-bound flattened sacs called A location and mechanism for the synthesis of sugars NADH and FADH2 provide electrons, energy is thylakoids. Stacks of thylakoids are called grana. would need to be created. 3. Broad leaves have a captured for ATP production, O2 is reduced making 2. solar energy + H2O + CO2 → (CH2O) + O2 large surface area for absorbing light energy and water. (7.5) 1. For each glucose molecule 3. Reduction—when a molecule gains electrons (e–) thin leaves promote efficient gas exchange, both of 2 ATPs are produced during glycolysis, 2 ATPs during and hydrogen ions (H+); Oxidation—when a molecule which promote photosynthesis. 4. As temperatures the citric acid cycle, and a maximum of 34 ATPs as gives up electrons (e–) and hydrogen ions (H+). rise in North America C3 plants might not be able a result of the electron transport chain for a total of (6.2) 1. Because plants have accessory pigments as to survive while C4 plants will have an advantage. 38 ATPs. Various cells produce less ATP depending well as chlorophyll a and b grouped in the pigment 5. As the world warms, C4 weeds are proliferating. on metabolic differences. 2. Each fat or oil molecule complex, they are able to gather solar energy of The cellulose in these weeds, as well as cellulose in contains three long-chain fatty acids and one glycerol. a broader range of wavelengths. 2. The pigment grasses, wood waste, and crop residues, is a potential complexes of PS II and PS I receive solar energy source of carbohydrate for ethanol production if and pass this energy from one pigment to another to
B-4 APPENDIX B Answer Key Many more acetyl-CoAs result from the breakdown of align along the spindle equator; Anaphase—sister 1.b. Documentation of the types of cancers that the three fatty acids than from the breakdown of one chromatids separate and move to each pole becoming appeared over time in the population exposed to the glucose molecule. Therefore many more ATPs result daughter chromosomes. Telophase—spindle radiation from Fukushima compared to a similar from the breakdown of a fat than from glucose. disappears and nuclear envelope forms around the population not exposed to the radiation would test 3. The amino groups are removed from the amino daughter chromosomes. 4. The cleavage furrow the idea. Care would be needed to restrict both acids and excreted as urea. The hydrocarbon backbones formed in animal cells between the two daughter populations from other cancer risks during the can enter the cellular respiration pathway at pyruvate, nuclei contracts until the two daughter cells duration of the study. 2. It could be that having at acetyl-CoA, or during the citric acid cycle. separate. In plants the rigid cell wall does not permit multiple copies of tumor suppressor genes is an cytokinesis by furrowing. Instead the cell builds a adaptation that elephants have developed against Testing Yourself new plasma membrane and cell wall between the two cancer. Those elephants with multiple copies survive daughter cells. (8.3) 1. Checkpoints regulate the cell longer and reproduce passing their genomes on to 1. a; 2. c; 3. a; 4. c; 5. b; 6. b; 7. a; 8. b; 9. c; 10. b; cycle by ensuring that each step is completed correctly their offspring. 3.a. BPA-like hormones could act as 11. c; 12. c; 13. c; 14. c; 15. d before the next step begins. 2. Internal and external an external signal stimulating cells to divide. signals are molecules that control the checkpoints of 3.b. Because BPA acts like a hormone very BioNow the cell cycle. Internal signals (cyclins) control the G1 few BPA molecules are needed to initiate the to S and the G2 to M transitions. External signals such pathway. Also, the signaling pathway is amplified The CHO comes from the food Jason Carlson ate and as growth factors and hormones stimulate the cell when executed. the oxygen is present in the air he breathed. Cellular to go through the cell cycle. 3. If apoptosis were not respiration produces the CO2 and the energy used to regulated the balance between controlled cell death CHAPTER 9 charge the battery powering the lights needed by the and the cell cycle would be disrupted. Normal cell plants. levels would be altered. (8.4) 1. Proto-oncogenes code Check Your Progress for proteins that promote the cell cycle and inhibit Thinking Critically apoptosis. Tumor suppressor genes code for proteins (9.1) 1. Meiosis is a type of nuclear division that that inhibit the cell cycle and promote apoptosis. reduces the number of chromosomes by half and 1. Malonate is a product of one enzymatic reaction in Mutations in these genes can lead to unregulated reorganizes the chromosomes to produce genetically the citric acid cycle and a substrate of the next enzyme cell growth. 2. Teleomere shortening regulates cell different gametes. This creates genetic diversity with in the cycle. Due to a feedback mechanism, excessive division by limiting the number of times a cell can each offspring being unique. 2. Adult humans produce amounts of malonate will inhibit the enzyme that divide. Without it cells continue to divide indefinitely. gametes by meiosis. A haploid sperm fertilizes a haploid produced it, thereby stopping the citric acid cycle. Rearrangement of segments of chromosomes results egg and a diploid zygote is formed which divides by 2. As we age, our mitochondria lose efficiency and in translocations which can disrupt genes that regulate mitosis to develop into an adult. 3. Chromosomes occur do not break down fats as quickly. This causes fats the cell cycle. This can lead to cancer. 3. The RB gene in pairs with each member called a homologous to accumulate in cells. Since fats and oils enter the is a tumor suppressor gene that when mutated leads to chromosome. One member comes from each parent. cellular respiration pathway as acetyl-CoA, there are retinoblastoma. Mutations in both alleles are required They carry the same types of genes but can vary as plenty of citric acid cycle substrates to create energy, for cancer to occur. The RET gene is a proto-oncogene to the traits they code for. During the cell cycle each and more glucose is not needed. Since the cells that when mutated can lead to thyroid cancer. It is homologous chromosome duplicates to form two already have plenty of energy, they ignore the insulin autosomal dominant so only 1 mutated allele is needed identical sister chromatids. 4. Crossing-over shuffles signal and do not readily take up glucose. Thus, fatty to increase the likelihood of cancer. (8.5) 1. Cancer genetic information between nonsister chromatids acid accumulation can lead to insulin resistance. cells lack differentiation, have abnormal nuclei, do not of a homologous pair, altering the types of alleles 3. Mitochondria and some prokaryotes are similar in undergo apoptosis, form tumors, undergo metastasis, on the chromosomes. The chromosomes from each form and function. Mitochondria resemble free-living and promote angiogenesis. 2. Treatments include: parent cell are shuffled during meiosis I to produce prokaryotic cells in that their inner membrane also has removing the tumor surgically, radiation therapy, new combinations unique to the daughter cells. invaginations. The inner membrane of mitochondria chemotherapy, and immunotherapy. 3. Evidence exists These processes create genetic variation which is like that of the prokaryote is the site of a metabolic that behaviors including not smoking, avoiding sun the basis of evolution. (9.2) 1. During prophase I pathway. 4. Humans cannot live without the electron exposure, moderating alcohol intake, and following a crossing-over between nonsister chromatids occurs. transport chains working in cells. Our metabolic need protective diet to maintain a healthy body weight and During metaphase I the tetrads align at the equator for ATP cannot be met by just glycolysis and the citric obtain proper nutrients, can reduce a person’s risk of with each homologue facing a spindle pole. Whether acid cycle. cancer. the homologue came from the father or from the mother does not matter in how they line up. Genetic CHAPTER 8 Testing Yourself variability in the daughter cells is increased by these processes. 2. During metaphase I tetrads Check Your Progress 1. b; 2. a; 3. d; 4. a; 5. c; 6. b; 7. a. G1; b. S; c. G2; (2 homologous chromosomes each consisting of d. prophase; e. metaphase; f. anaphase; g. telophase; 2 chromatids) line up at the spindle equator. During (8.1) 1. Single-celled organisms divide in order to h. cytokinesis; 8. a; 9. d; 10. c; 11. b; 12. a; 13. b; metaphase II the dyads (1 chromosome consisting of reproduce. Multicellular organisms must undergo 14. c; 15. a; 16. a; 17. e 2 sister chromatids) align at the spindle equator. cellular reproduction in order to develop from a single 3. During meiosis I the chromosome number is halved cell. Mature organisms need to replenish worn-out BioNow and the genetic information is reshuffled. During cells and repair injuries. 2. Before cell division the meiosis II the cells reproduce like in mitosis, except chromosomes are duplicated to produce two sister The rooting hormone acts as an external signal they are haploid. (9.3) 1. Mitosis produces 2 daughter chromatids, each of which are held together at a stimulating cells to divide. Likely the hormone cells while meiosis produces 4. 2. Mitosis produces centromere. Each chromatid is identical to the other. interacts with DNA in the S phase of interphase daughter cells which are diploid while meiosis 3. Chromatin is wound around histones to produce promoting DNA replication. produces haploid daughter cells. 3. In meiosis I nucleosomes. The histones and the nucleosomes crossing-over during synapsis occurs and homologues package the chromatin so that it fits inside the nucleus. Thinking Critically are separated into the daughter nuclei irrespective (8.2) 1. The cell cycle is an orderly set of steps with of their being from the father or mother. Genetically checkpoints that is followed when cells duplicate. It 1.a Cancer results from a series of mutations that different nuclei are created. The chromosome number ensures accuracy of the process. 2. During interphase accumulate in cells over a lifetime. It could be that is halved. During meiosis II the cells replicate like in the cell is performing its normal functions. In the G1 the appearance of different cancers at different times mitosis except that they are haploid. Mitosis results in phase organelles are duplicated. During S phase DNA is due to some cancers requiring a larger number of daughter cells which are identical to the parents. is duplicated, and in G2 growth occurs and proteins mutations to occur before they develop. Cancers that (9.4) 1. If nondisjunction occurs during meiosis I or are synthesized that are needed for cell division. require more mutations to occur would meiosis II, a gamete and therefore a zygote, 3. Prophase—chromosomes condense and consist of more likely occur after a longer period of time. two sister chromatids; Metaphase—chromosomes
APPENDIX B Answer Key B-5 could have an abnormal chromosome number. affected children can have unaffected parents, that (homozygous dominant or heterozygous dominant) 2. Monosomy results when an individual is missing heterozygotes have a normal phenotype, and that or the regular fish (homozygous recessive). If the one chromosome. Trisomy results when an individual both males and females are affected equally. The color was a codominant trait then three different has one extra chromosome. 3. Abnormalities in individual III-1 is heterozygous because she had phenotypes would be produced from the genotypes the sex chromosomes occur only in the X or Y affected children. An autosomal dominant pedigree of homozygous dominant, heterozygous, and chromosomes. Autosomal abnormalities occur in (Fig. 10.10) shows that affected children have at least homozygous recessive. any of the other 22 pairs of chromosomes. Newborns one affected parent, that heterozygotes are affected, with abnormal number of sex chromosomes are more and that males and females are equally affected. The Thinking Critically likely to survive than those with abnormal numbers of individual II-2 is heterozygous because he had one autosomal chromosomes. unaffected child. The genotype of individual II-3 1. a. CcPp × CcPp would produce 9/16 purple (C_P_) cannot be determined because there are no unaffected and 7/16 white offspring (C_pp, ccP_, or ccpp). Testing Yourself children present. 2. With an autosomal recessive 2. a. Set up a cross between a true-breeding strain disorder like cystic fibrosis, individuals with normal of flies that have the trait with a true-breeding strain 1. d; 2. a; 3. d; 4. a; 5. f; 6. h; 7. c; 8. g; 9. b; 10. e; phenotypes can be heterozygous (they can carry a that does not. If no offspring of the cross have the 11. c; 12. b; 13. b; 14. c; 15. d; 16. c dominant and recessive allele). Each parent is capable trait it is recessive. If all the offspring have the trait of producing gametes with the recessive allele it is dominant. b. Drosophila have lots of offspring, Thinking Critically which can combine in the offspring to produce the a short generation time, can be housed and raised disorder. 3. Sickle-cell disease is autosomal recessive. inexpensively, and the ethics of treatment of the flies 1. A mosaic such as (46, XY/47, XXY) may result Homozygotes have sickle-shaped red blood cells as is broader than with humans. 3. a. The technology from nondisjunction occurring during mitosis, children but the heterozygotes appear normal unless could be used to produce only female offspring which especially at a very early stage of development. A stressed by low oxygen levels. Huntington disease is reduces the probability of an X-linked genetic disorder fertile Klinefelter mosaic may arise from an individual autosomal dominant but the disease does not appear showing as a phenotype. b. Parents could select the in which normal (46, XY) embryonic cells gave rise until middle age when individuals may have already sex of their children based on cultural preferences to the testes. The symptoms usually associated with passed it on to their children. (10.3) 1. Incomplete thus distorting the balance of males to females in the Klinefelter individuals would be less pronounced in dominance is exhibited when the heterozygote has population. mosaics and it is possible that they could produce an intermediate phenotype between that of either normal sperm and reproduce. 2. Hypotheses to homozygote. An example is pink four-o’clock flowers. CHAPTER 11 explain the relationship between the increase in Down Codominance is exhibited when both alleles in a syndrome with advancing maternal age include: (1) heterozygote are fully expressed. 2. The type O child Check Your Progress The older a woman is, the longer her oocytes have would need to have inherited a recessive i allele from been arrested in meiosis, and the higher the risk that both parents. The type AB parent does not have an (11.1) 1. DNA contains a series of nucleotides, each these oocytes have been exposed to mutagens which i allele. 3. Polygenic traits are governed by several consisting of a deoxyribose sugar, a phosphate, might cause nondisjunction; (2) A woman may have a sets of alleles often on different chromosomes. The and a nitrogen-containing base: cytosine, thymine, pool of oocytes resulting from nondisjunction which dominant alleles have an additive effect creating adenine, or guanine. Two strands of nucleotides are take longer to mature, and thus are more commonly a bell-shaped distribution curve of phenotypes. arranged antiparallel to each other and are twisted released as she ages; (3) Estrogen levels (which Multifactorial traits are controlled by polygenes that into a helix with cytosine hydrogen bonded to guanine control the rate of meiosis in developing oocytes) are subject, in varying degrees, to environmental and adenine to thymine. 2. First, helicase unwinds drop with advancing maternal age and may slow down influences. 4. If genes are linked on one chromosome the double-helix structure by breaking the hydrogen the rate of meiosis. This might allow nondisjunction then they are inherited together. In a two-trait cross the bonds between the nucleotides; DNA polymerase to occur more frequently in older women. 3. Large assumption is that the alleles are on nonhomologous adds nucleotides to the complementary new strand in amounts of genetic variability in a population allow chromosomes and will be subject to independent a 5′–3′ direction; DNA ligase then seals any breaks in the population to more quickly adapt to changing assortment. It is possible that one gene can override the deoxyribose-phosphate backbone of the daughter conditions. For example, if a population is suddenly the expression of another gene. This type of gene strand. 3. DNA contains the sugar deoxyribose; RNA exposed to a new pathogen, it is likely that at least a interaction appears as a variation of Mendel's laws of has the sugar ribose. DNA has the base thymine; few individuals will be able to survive the pathogen inheritance involving dominant and recessive traits. RNA has the base uracil. DNA is double-stranded; and the species would continue. (10.4) 1. Since males are XY, some sperm will contain RNA is single-stranded. 4. mRNA carries the an X chromosome and others will contain a Y. genetic information from DNA in the nucleus to CHAPTER 10 2. With X-linked recessive inheritance (Fig. 10.25) the ribosomes in the cytoplasm; rRNA combines more males than females are affected, affected with proteins in the cytoplasm to form ribosomes, Check Your Progress sons can have parents with normal phenotypes, where proteins are synthesized; tRNA transfers affected female offspring have an affected father, amino acids to a growing polypeptide at a ribosome. (10.1) 1. Mendel’s experiments explained the patterns and the mother must be affected or be a carrier. With (11.2) 1. Genetic information flows from DNA to of inheritance of traits seen in families and the autosomal recessive inheritance, males and females RNA to proteins. DNA is transcribed into mRNA, variation between offspring seen from one generation are affected equally, heterozygotes have a normal which moves from the nucleus to the ribosomes in to the next. 2. The offspring resulting from a cross phenotype, and affected children can have unaffected the cytoplasm and undergoes processing before it is between two individuals who are heterozygous for parents. 3. Color blindness and Duchenne muscular translated into a protein. 2. The genetic code in DNA one trait (Tt) will produce three different genotypes, dystrophy are sex-linked disorders. defines the sequence of amino acids in the proteins TT, Tt, tt in a 1:2:1 ratio. Because the homozygous a cell makes. This stored information is translated dominant (TT) and the heterozygous (Tt) individuals Testing Yourself from DNA to RNA and eventually results in a specific look alike, the phenotypic ratio will be 3:1. 3. The polypeptide synthesized at a ribosome. This process probability of producing a short plant with green 1. a; 2. d; 3. d; 4. a. TG; b. tg; c. TtGg; d. TTGG; of protein synthesis in which genetic information pods is 3/16. 4. Traits are carried by a homologous e. TtGg; f. TTgg; g. Ttgg; h. TtGG; i. ttGG; j. TtGg; flows from DNA to RNA to protein is known as the pair of chromosomes. One homologue carries the k. ttGg; l. ttgg; 5. a; 6. b; 7. a; 8. b; 9. a; 10. a; 11. a; central dogma of molecular biology. 3. The mRNA trait from the mother and the other carries the trait 12. e; 13. e; 14. d; 15. c. molecule must be processed by capping, the addition from the father. When following two traits, two of a poly-A tail, and splicing in order for it to function homologous pairs are considered. During meiosis the BioNow properly in protein synthesis. 4. Ribosomes are made homologues separate from each other independently up of ribosomal RNA and proteins arranged as large and go into different gametes no matter whether they Multiple crosses of the glowfish with other glowfish and small subunits. At the beginning of translation, came from the father or the mother. All combinations would provide the evidence. If the color was due to a the large ribosomal subunit joins the small unit and a of chromosomes are possible. This is what Mendel dominant trait then crosses between glowfish could tRNA-amino acid complex containing an anticodon saw with his experiments with peas. (10.2) 1. An produce two possible phenotypes: the colored fish binds to the codon on the mRNA. The amino acid is autosomal recessive pedigree (Fig. 10.9) shows that
B-6 APPENDIX B Answer Key then added to the growing polypeptide. (11.3) 1. In parents of a child, or unidentified bodies. In addition, Thinking Critically prokaryotes, a single promoter controls transcription it can be used to detect mutations that can lead to an in a unit of several genes. In eukaryotes, there is a increased risk of disease. 4. Genomic editing may 1. Advantages include efficiency of the treatment, promoter for each gene. Prokaryotes regulate gene be more efficient because the guide RNA molecule since many viruses could deliver the genes rapidly. expression mostly by controlling transcription. can locate the specific nucleotides of interest in the Also, the process would be relatively noninvasive. Eukaryotes have many mechanisms for controlling target DNA. The process can be applied to almost A problem might be that the genes could be inserted gene expression, such as turning a gene on or off, all organisms, and it can be used to either inactivate in the wrong place in the genome, disrupting other regulating the speed at which a gene is expressed, and a gene or insert a new DNA sequence. Recombinant genes and either making them nonfunctional or controlling how long it is expressed. 2. Eukaryotes can DNA processes may be less efficient because both an altering them to produce harmful gene products. regulate gene expression in the nucleus by chromatin organism with the gene of interest and an organism Another possible problem is that the viruses could condensation, control of DNA transcription, and housing the vector (plasmid) are required. Also, two promote cell division, resulting in unregulated cell mRNA processing. In the cytoplasm, translation of enzymes, a specific restriction endonuclease and growth leading to cancer. 2. Human recombinant mRNA can be allowed or delayed, mRNA lifetimes a DNA ligase, must be used. (12.2) 1. The goal of insulin matches human insulin completely. Cow or can vary, and how long proteins exist can be reproductive cloning is to create an identical copy pig insulin differs slightly from human insulin. Using controlled. 3. There are many transcription factors in of an individual organism. The goal of therapeutic human recombinant insulin would avoid any potential eukaryotes that form a complex that binds to DNA cloning is to produce cells or tissues that can be antibody response to the insulin. 3. Genes whose to help separate the DNA strands and promote the used in the study of cell specialization or in treating products are involved in glycolysis, the citric acid positioning of RNA polymerase. Because there are human illnesses. 2. Embryonic stem cells are obtained cycle, and the electron transport chain would likely many transcription factors working together, a higher from an embryo. Adult stem cells are harvested from be similar. level of control over transcription is possible. many organs in the body. 3. Embryonic stem cells are totipotent because they can differentiate into CHAPTER 13 Testing Yourself any type of cell in the body. Adult stem cells are multipotent, meaning that they are limited as to the Check Your Progress 1. a. sugar-phosphate backbone; b. purine base; types of cells they can produce. (12.3) 1. Transgenic c. hydrogen bonds; d. deoxyribose sugar; e. nucleotide; organisms have had a foreign gene inserted into their (13.1) 1. Mutations alter the sequence of nucleotides 2. a; 3. d; 4. a; 5. d; 6. b; 7. b; 8. a; 9. c; 10. c; 11. b; genome. Genetically modified organisms have had in DNA. Alleles are variations of a gene, and 12. b; 13. b; 14. d; 15. b their genetic material modified using recombinant a mutation can create a new allele. 2. When a DNA technology. 2. Transgenic bacteria have been transposon moves, it inserts its DNA sequence BioNow used to produce insulin, clotting factor VIII, human into another chromosome, altering the sequence growth hormone, tissue plasminogen activator, and of nucleotides. This can result in a mutation that 1. Light and increased temperature could influence hepatitis B vaccine. Frost-minus strains of bacteria disrupts a gene. 3. The single base change that occurs brain function, causing hormone production and have been engineered that can reduce the formation of in a point mutation may or may not change the one release. The hormones could influence gene ice crystals on strawberries and other fruits. Naturally- amino acid that is coded for, so the function of the expression, leading to ovulation and sperm production occurring bacteria that degrade oil have been protein may not be altered. A frameshift mutation as well as behavior changes involved with mating. engineered to work more efficiently. 3. Transgenic alters all the downstream codons and often results 2. Regulators of the expression of the developmental plants resistant to herbicides have increased crop in a dysfunctional protein. (13.2) 1. A deletion can genes could include increased temperature, exposure yields while reducing herbicide use. Transgenic food result in the loss of one allele of a gene, possibly to light, and the passage of time. Also, perhaps only crops have been developed that have higher nutrient leading to a syndrome. With a duplication, a segment those larvae exposed to adequate food while in the quality and contain more healthful fats. Transgenic of the chromosome is repeated and thus there may wood could develop into adults. animals that have the gene for bovine growth hormone be more than two alleles for a gene. This disrupts grow bigger and provide more meat. These advances normal gene function but does not eliminate the Thinking Critically increase food production. Plants have been developed allele. 2. Inheritance of a chromosome with a that have leaves that take in more carbon dioxide translocation can leave an individual with one copy 1. DNA from the heat-killed virulent strain contains and lose less water, which helps the crops grow in a of certain alleles and three copies of other alleles. genes that produce the virulence. Somehow, the living wider range of climate conditions. (12.4) 1. The goals When a segment of DNA is inverted, duplication nonvirulent bacteria obtained some of this DNA, include an understanding of what genes are present and deletion can occur in later generations, resulting converting them into a virulent strain. 2. A medicine in a genome, the gene products and their functions, in disrupted gene expression, 3. Cri du chat could be developed whose effect on gene regulation and the function of the intergenic DNA. 2. Comparing syndrome results from a deletion; the end piece was inheritable. Such a medicine could be given just different genomes identifies their differences and of chromosome 5 is missing. Alagille syndrome once, and its effect would be passed on to following similarities, which provides information about results from a translocation between chromosomes generations. 3. a. The basic requirements are being evolutionary history. Insight into how the human 2 and 20. (13.3) 1. Karyotyping can detect abnormal able to store genetic information that is inheritable, species evolved can be gained by comparing the numbers and shapes of chromosomes as well as their having the stored information be expressible, human genome with those of our recent ancestors. banding patterns, which may indicate chromosomal containing variations that allow for evolution, and 3. Proteomics is important to drug development mutations. 2. Genetic disorders can be detected if a being small enough to be packaged inside a cell. because knowing the structure and function of cell specific protein is present or absent in the blood. If b. If the genetic information turns out to be very proteins and examining how they interact gives insight a protein is absent, then the gene is altered or it is similar to our own, that implies that DNA has unique into how drug molecules will react with them. not being expressed. Alternatively, a protein might qualities that are universal. If the genetic information be present that is normally absent. Testing DNA is very different, then different storage molecules are Testing Yourself involves determining if the sequence of bases in a possible. person’s DNA has been changed. Such changes can 1. d; 2. d; 3. c; 4. b; 5. c; 6. c; 7. d; 8. b; 9. c; 10. c lead to disorders. 3. Ultrasound images help doctors CHAPTER 12 evaluate fetal anatomy, but not the genome of the BioNow fetus. Amniocentesis uses a long needle to withdraw Check Your Progress amniotic fluid containing fetal cells. The process The glowing fish are genetically modified, as does have a low risk (0.6%) of causing a spontaneous (12.1) 1. A bacterial plasmid is a ring of accessory indicated by their ability to pass the glowing trait on abortion. In chorionic villus sampling (CVS), a DNA that serves as a vector to carry foreign DNA to their offspring. The gene for glowing may have suction tube is used to remove chorionic villi cells in the production of recombinant DNA. 2. PCR is been inserted into the fishes' genome, or CRISPR from the region where the placenta develops. This used to produce many copies of a specific segment may have been used to edit the fishes' color genes to procedure can be performed as early as the 5th week of DNA, which is usually a few hundred base pairs produce the glow. of pregnancy, and it carries a 0.7% risk of spontaneous long. 3. DNA fingerprinting can be used to identify sources of DNA, such as bacteria or viruses that are causing an infection, people involved in a crime scene,
APPENDIX B Answer Key B-7 abortion. 4. Changes in base sequences can be acquired characteristics explains the changes seen have the traits that improve the ability to reproduce. identified and used as genetic markers of diseases. over time. 2. According to the idea of inheritance By selecting the fittest male, the female is improving The markers can be detected by conducting a complete of acquired characteristics, an individual organism the chances that her traits will be passed on to her genetic profile, using microarrays, or analyzing the changes in response to its environment. It acquires offspring. 3. Mutation, recombination, independent products of restriction enzyme digestion of a subject’s new characteristics that it passes on to its offspring. assortment, gene flow, disruptive selection, and DNA using gel electrophoresis. (13.4) 1. Ex vivo gene In the process of natural selection, individuals' diploidy. (15.2) 1. The various alleles at all the therapy procedures are carried out on tissues removed survival depends on how well they are adapted to gene loci in all individuals make up the gene pool from the body, treated with viruses carrying the gene their environment. Those who are well adapted of the population. The gene pool of a population of interest, and then reintroduced into the body. With survive to reproduce, and those who are not die out. is described in terms of allele frequencies. 2. The in vivo gene therapy, the gene of interest is delivered 3. The individuals best adapted to an environment are Hardy-Weinberg principle states that the equilibrium directly into the body. 2. Genes may be delivered the fittest because they survive and reproduce. The of genotype frequencies in a gene pool will remain by spraying them into the nose or by injecting them adaptations that allow survival in an environment are stable in each succeeding generation of a sexually into particular tissues or organs. Liposomes or selected for over generations. (14.2) 1. The finches reproducing population as long as five conditions adenoviruses may also be used to carry the genes show that a common ancestor can give rise to different are met. Microevolution can be detected and into cells and tissues. 3. Ex vivo: SCID treated species through adaptation to unique environments. measured by noting the amount of deviation from by inserting ADA gene into stem cells; familial In this case, the environments on different islands Hardy-Weinberg equilibrium that is exhibited by the hypercholesterolemia where liver cells are infected varied and put different pressures on the finches that genotype frequencies in a population. 3. To prevent with virus carrying gene for the normal cholesterol arrived there. 2. Vestigial structures show that present- microevolution in a population no mutations must receptor; cancer when patient cells are treated to day organisms have ancestors from which they have occur, there is no gene flow, only random mating express cancer antigens to stimulate the immune evolved. These structures are not functional now but happens, there is no genetic drift, and no natural system. In vivo: cystic fibrosis treated when gene for they were in the ancestors. 3. Homologous structures selection functions. 4. Mutations are ultimately normal chloride ion carrier is sprayed into the nose or share an anatomical similarity that reflects a common responsible for all the genetic variability on which carried into the lungs by liposomes; VEGF is injected ancestry. Analogous structures have a common evolution depends. 5. Gene flow is the migration into the heart to stimulate growth of coronary blood function but are not constructed similarly and do not of alleles into or out of populations, changing their vessels; RA when anti-inflammatory gene is injected indicate a common ancestry. frequency and leading to microevolution. Nonrandom directly into the affected joint. mating pairs individuals according to their phenotypes Testing Yourself and ultimately their genotypes. Inbreeding increases Testing Yourself the proportion of homozygotes in the population, and 1. b; 2. d; 3. b; 4. b; 5. a; 6. e; 7. e; 8. a; 9. c; 10. b; assortative mating causes the population to subdivide 1. c; 2. b; 3. a; 4. b; 5. c; 6. a; 7. c; 8. b; 9. c; 10. b 11. a; 12. c; 13. b; 14. c into phenotypes. Nonrandom mating can therefore result in microevolution. 6. With genetic drift, allele Thinking Critically BioNow frequencies in a gene pool change gradually over time due to chance. In a small population, the probability 1. A genetic counselor works for the patient but may The quail eggs had variations in their coloration that an individual with a rare genotype might pass be uncomfortable with the ethics of not disclosing that influenced the degree to which they were alleles to the next generation is greater. It will be more information. In light of this, the counselor needs camouflaged in their environment. In this experiment, likely that a decrease or increase in the frequency of to educate the patient about DNA sequencing and it was supposed that the environment shifted to be this genotype will result. all the information it can divulge before the testing either white or dark, which created a pressure on the is performed. Information about other diseases, quail population to evolve to adapt to this change. The Testing Yourself their risks, and the emotional and financial impact whitest eggs would survive predation in the white of having a child with the disease should be environment, and the darkest eggs would survive in 1. d; 2. a; 3. c; 4. b; 5. c; 6. a; 7. d; 8. c; 9. c; 10. b; 11. a communicated in advance. Formal agreements about the dark environment. Those eggs would hatch and how to handle added information resulting from the produce offspring, which in turn would produce eggs BioNow testing should be established between the counselor that shared the phenotypes of the parents. Under the and the patient. 2. The adenovirus may have inserted artificial selection imposed by the experiment, the The experimenter selected the eggs that were itself into or near a gene that is involved in controlling frequencies of the lightest and darkest eggs increased. incubated to produce the next generation. This the cell cycle, such as a proto-oncogene or a tumor imposed a pressure on the population analogous to suppressor gene. If so, disrupting the gene may have Thinking Critically nonrandom mating. The distribution of egg coloration inactivated it. In the case of the infants with XSCID, was altered over generations by this disruptive the virus was found to have inserted itself near a 1. Humans and other mammals have these selection, increasing the frequencies of the lightest proto-oncogene called LMO-2. 3. When disorders homologous structures because we share a common and darkest eggs. are homozygous recessive, the recessive allele can ancestor that had such a structure. The presence of be present in a portion of the population at all times. this structure informs us about the dietary history of Thinking Critically Only when two heterozygous carriers mate is there humans. It suggests that humans previously ate more a chance that the offspring will have the disorder. plants than they currently do. 2. Different genes are 1. a. By applying three times as much pesticide, Sometimes the recessive allele confers an evolutionary under varying levels of evolutionary pressure based the second farmer generates pesticide-resistant advantage. For example, carriers of sickle-cell disease on their function and importance for an organism’s insects that are selected for over the five years. are more resistant to malaria. survival. 3. Islands are isolated and provide unique b. The resistant insects have an extreme phenotype environments for the organisms that live there. The that is being selected for, an example of directional CHAPTER 14 particular conditions in these environments influence selection. c. The insect population on the first farm the evolution of these organisms in a specific is in equilibrium because the percentage of crop loss Check Your Progress direction. remains constant, indicating the same number of resistant insects in each generation. 2. a. The females (14.1) 1. Cuvier founded the science of paleontology. CHAPTER 15 are selecting the bright-feathered males as mates He thought that species were fixed and did not change because they perceive them to be more fit. This is over time. Instead, catastrophes occurred that led Check Your Progress an example of sexual selection. b. By selecting a to mass extinctions. Repopulation of an area after bright-feathered male, a female is more likely to a catastrophe led to new fossils appearing in a new (15.1) 1. Directional selection favors one extreme have bright-feathered offspring that will have greater stratum, which explains the changes seen in the fossil phenotype. Stabilizing selection favors the success in generating more offspring. This promotes record. Lamarck proposed that animals change to intermediate phenotype. Disruptive selection nonrandom mating. c. In their natural environment, adapt to their environments and these changes are favors two or more extreme phenotypes over any mate dark-feathered females with light-feathered passed on to their offspring. This inheritance of intermediate phenotype. 2. In females, sexual males and measure the reproductive success of the selection favors the fittest males, meaning those that
B-8 APPENDIX B Answer Key offspring. Compare that to the reproductive success Thinking Critically genes originated in bacteria, with mitochondria being of offspring from mating dark-feathered females and related to certain bacteria and chloroplasts related dark-feathered males. 1. a. ferns; b. produce seed; c. naked seeds; d. conifers, to cyanobacteria. 2. Protists are eukaryotes with a needle-like leaves; e. ginkgos, fan-shaped leaves; nucleus and a wide range of organelles. Many are CHAPTER 16 f. enclosed seeds; g. monocots, one embryonic single-celled. They are a diverse group that represent leaf; h. eudicots, two embryonic leaves. 2. On the common ancestors of different multicellular Check Your Progress the Hawaiian Islands, species become isolated on organisms. 3. Archaeplastids have chloroplasts derived islands that are far away from each other and the from endosymbiotic cyanobacteria; green algae (16.1) 1. A biological species is a group of organisms mainland. Over generations, they adapt to the island are an example. The SAR supergroup consists of that can interbreed, have a shared gene pool, and environment, which is often different from the stramenopiles, which are photosynthetic but evolved are reproductively isolated from members of other mainland environment from which they came. The differently than green and red algae; alveolates, which species. This is a testable concept that does not depend Florida Keys are close enough to each other and close have an internal series of cavities; and rhizarians on physical appearance. 2. The biological species enough to the Florida mainland to allow species to which are amoeba-like organisms with external concept cannot be applied to asexually reproducing move among the islands and the mainland. Thus, they shells. Examples of these three groups are diatoms, organisms. In addition, reproductive isolation may are not reproductively isolated and further speciation ciliates, and foraminifera. Excavata lack mitochondria not be complete, so some breeding between species does not occur. 3. a. Because humans share much of and have distinct flagella and/or oral grooves; may occur. 3. Prezygotic isolating mechanisms do their genome with other organisms, basic research in euglenids are an example. Amoebozoa move by not allow zygotes to be formed. Examples are habitat, systematics at all levels has the potential to provide means of pseudopods; slime molds are an example. temporal, behavioral, mechanical, and gametic beneficial information to humans and the organisms Opisthokonts are chemoheterotrophs with flagellated isolation. Postzygotic mechanisms allow zygotes to that make up their world. b. If a country has the cells; choanoflagellates are an example. be formed, but the zygotes either die or develop into financial capacity to fund basic systematics research offspring that are infertile or that produce infertile while attending to the needs of its population, such Testing Yourself offspring. Examples are zygote mortality, hybrid research should be a priority because of the potential sterility, and low F2 fitness. 4. Allopatric speciation benefits that could result. 1. c; 2. d; 3. a; 4. c; 5. c; 6. c; 7. a; 8. b; 9. a; 10. d; occurs when a geographic barrier stops gene flow. 11. c; 12. c; 13. d; 14. a; 15. d Ensatina salamanders in California are separated CHAPTER 17 by the Central Valley and limited gene flow occurs Thinking Critically between the eastern and western populations. Two Check Your Progress distinct forms exist in southern California that 1. Protists are members of the domain Eukarya and interbreed only rarely. Sympatric speciation produces (17.1) 1. Viruses are composed of an outer capsid of are more closely related to archaea than to bacteria. reproductively isolated groups without geographic protein subunits and an inner core containing DNA Archaea and eukarya have certain ribosomal proteins isolation. Polyploidy in wheat plants resulted in or RNA. 2. In the lytic cycle, a virus enters a host in common that are not shared with bacteria. They the reproductive isolation of bread wheat. 5. One cell and replicates, producing many copies of itself. initiate transcription in the same way and have similar mainland finch species was probably an ancestor to Alternatively, in the lysogenic cycle, the virus, after tRNAs. Viruses are not shown on the tree because all existing species on the Galápagos Islands through infecting the cell, may enter a latent stage in which they are acellular and are not considered to belong to adaptive radiation. Each it is dormant but ready to replicate in the future. any of the three domains of life. 2. Bacteriophages can new species acquired adaptations in response to the 3. In order to enter a cell, a virus must have a specific infect bacteria in a patient’s body and initiate a lytic unique environment on the island it inhabits. (16.2) capsid protein that binds to a specific receptor protein cycle that will kill the bacteria. The most important 1. Fossils provide durable evidence of life-forms that on the cell's surface. (17.2) 1. A viroid is composed benefit is the ability to treat infections caused by is relatively complete and can be dated. They display of naked RNA, not covered by a capsid. A virus has antibiotic-resistant bacteria. The main shortcoming is evolutionary changes that have occurred over time. an inner core of DNA or RNA and a capsid composed that bacteria will almost certainly evolve resistance to 2. The punctuated equilibrium model says that periods of protein subunits. 2. Prions are proteins that have bacteriophage infection. 3. a. Labeling antibiotics as of no change in evolution are interrupted by periods changed shape and can interact with normal proteins being ineffective against viruses would help educate of relatively rapid speciation. 3. Continental drift, loss to change their shapes. This causes fatal infections consumers. Not everyone would read the label or of habitat, the crash of a meteorite into the Earth, and and neurological disorders. Viroids are strands of respond to the information it contains, but some climate change have contributed to mass extinctions. naked RNA. 3. Prion disorders include kuru, mad people would respond to the message and change (16.3) 1. Species, genus, family, order, class, phylum, cow disease, scrapie (which attacks sheep), and their behaviors. b. The laws covering liability for kingdom, domain. 2. Homologous structures are Creutzfeldt-Jacob disease in humans. (17.3) 1. Small withholding antibiotic use should be changed. It similar anatomically because they are derived from organic molecules formed from inorganic chemicals is likely that physicians would then become more a common ancestor. Analogous structures have the as the Earth cooled. Macromolecules self-assembled accountable for prescribing antibiotics, and if they same function in different groups and do not share from the small organic molecules and became were protected from lawsuits for not prescribing a common ancestry. 3. Taxonomy is concerned with surrounded by a barrier that defined the inside and antibiotics, they could afford to be more conservative identifying, naming, and classifying organisms. It the outside of a cell-like structure. Within the cell- about the prescriptions they write. uses scientific naming rules to establish a hierarchy like structure (protocell), the reactions of cellular of categories. Systematics attempts to define the metabolism evolved. 2. Cocci (spheres), bacilli (rods), CHAPTER 18 evolutionary history of organisms using fossils, and spirilla or spirochetes (spirals). 3. Conjugation— comparative anatomy and development, and molecular transfer of DNA from cell to cell; transformation— Check Your Progress data. 4. The three-domain system adopts a category of transfer of DNA from the environment to a cell; classification above the level of kingdom. It is based transduction—transfer of DNA from cell to cell by a (18.1) 1. The green algae and land plants contain on the sequencing of rRNA genes. It consists of the bacteriophage. 4. The plasma membrane of archaea chlorophylls a and b and accessory pigments, store domains Bacteria and Archaea, which include the have unusual lipids so they can survive in extreme carbohydrates as starch, have cellulose in their cell prokaryotes, and the domain Eukarya, which includes environments such as conditions of high heat. They walls, and form structures that protect the zygote. protists, animals, fungi, and plants. have diverse types of cell walls, sometimes containing 2. (1) Protection of the embryo; (2) evolution of proteins or polysaccharides but not peptidoglycan. vascular tissue; (3) evolution of leaves (microphylls Testing Yourself They also have unusual metabolic characteristics such and megaphylls); (4) evolution of seeds; (5) evolution as the ability to generate methane or live in high-salt of flowers. 3. Meiosis forms a haploid spore from a 1. c; 2. c; 3. b; 4. f; 5. a; 6. g; 7. d; 8. e; 9. h; 10. b; environments. Because of these characteristics, they diploid sporangium, which undergoes mitosis and 11. e; 12. d; 13. a; 14. c; 15. a. 3, with purple, orange, do not compete with bacteria. (17.4) 1. Both forms gametes. Following fertilization, a diploid and yellow shading; b. vertebrae, amniotic egg and mitochondria and chloroplasts have double zygote is formed that develops into a sporophyte internal fertilization; c. snake and lizard, because they membranes and distinct genomes. Their ribosomal by mitosis. (18.2) 1. Nonvascular plants do not share the most derived traits have true roots, stems, or leaves like vascular plants do. 2. The dominant generation of a moss is the
APPENDIX B Answer Key B-9 gametophyte; for a fern, the gametophyte stage is evolution of the other fungal groups. Cell walls nonliving cuticle and undergo molting. They have tiny and the sporophyte generation is dominant. of fungal ancestors may have contained chitin, a pseudocoelom. 2. (1) Jointed appendages; Mosses are nonvascular and lack true roots, stems, a feature shared by all modern fungi, including (2) exoskeleton; (3) segmentation; (4) well-developed and leaves. They are short and require a moist chytrids. Fungal ancestors may have had an nervous system; (5) variety of respiratory organs; environment to live in and reproduce. Ferns have alternation-of-generations life cycle, as do some (6) metamorphosis. 3. Insects are so numerous and a vascular system with true roots, stems, and chytrids. 3. Human skin is dry and the cells that diverse because they show remarkable structural leaves and can live in drier environments and grow make up the skin are constantly being shed. Humans and behavioral adaptations that allow them to live taller. 3. Following pollination, the pollen grain keep their skin relatively clean which discourages in many different habitats. (19.5) 1. Echinoderms germinates and a nonflagellated sperm travels in fungal growth. Lungs, however, provide a moist and have radial symmetry as adults and a water vascular a pollen tube to the egg produced by the female protected environment that is well vascularized and system with tube feet for locomotion. They lack gametophyte. Following fertilization, the zygote supportive of fungal growth. a head and a brain and are not segmented. 2. The becomes the sporophyte embryo, tissue within chordates have a dorsal supporting rod, dorsal the ovule becomes the stored food, and the ovule CHAPTER 19 tubular nerve cord, pharyngeal pouches, and a becomes the seed coat. 4. To reproduce, angiosperms postanal tail. Mammals are amniotes and share an require the dispersal of pollen from flower to Check Your Progress ancestor with reptiles. 3. Tunicates—four chordate flower. Wind and pollinators such as insects, birds, characteristics as larvae; lancelets—four chordate bats, and flies help disperse the pollen. (18.3) 1. A (19.1) 1. Multicellularity; development of tissues and characteristics as adults and segmentation; jawless fungus is made up of hyphae packed together to cellular organization into germ layers; differences fishes—vertebrae; cartilaginous fishes—jaws; form a mycelium. The cell walls are composed of in symmetry—bilateral and radial; cephalization— bony fishes—skeleton; lobe-finned fishes—lungs; chitin. The cells are divided by septa, which contain localization of brain and specialized sensory amphibians—limbs; reptiles and birds—amniotic pores that allow the movement of cytoplasm from receptors; development of a coelom; segmentation— egg; mammals—mammary glands. 4. The amniotic one cell to another. 2. Basidiomycota—dikaryotic repetition of body parts along the length of the egg eliminated the need for a water environment hyphae form a mushroom consisting of a stalk and body. 2. Animals are chemoheterotrophs that digest during development, which made development on a cap; Ascomycota—ascocarp shaped like a cup; their food with a digestive system. They reproduce land possible. It provides gas exchange, nutrients, Glomeromycota—form arbuscular mycorrhizae sexually to produce a fertilized diploid egg that removal of nitrogenous wastes, and protection from (AMs) with the roots of land plants; Zygomycota— undergoes a complex order of developmental desiccation and mechanical harm. 5. Mammals have have specialized hyphae for different functions; steps. Specialized tissues develop, such as muscles exhibited multiple adaptations that have allowed Chytridiomycota—have flagella and are mobile; and nerves, which provide the ability to move. them to live in many different environments. Microsporidia—obligate parasitic fungi. 3. A lichen Plants can photosynthesize but cannot move, and (19.6) 1. The anthropoids include the monkeys, is composed of a fungus and a cyanobacterium or a fungi digest their food externally and absorb the apes, and humans; hominins just the species green alga. The fungus provides protection, water, and nutrients. 3. Protostomes are characterized by Homo sapiens and our close humanlike ancestors. minerals, and the photosynthesizer provides organic spiral cell division when the embryo first forms 2. Among primates, the evolutionary trend was nutrients. 4. Oral candidiasis—Candida albicans and by a blastopore that becomes the mouth. If a toward larger and more complex brains. The infects the mouth and tongue producing painful coelom is present, it is formed by the splitting of development of the ability to stand erect and blisters. It can occur after antibiotic use or in states the mesoderm. Deuterostomes are characterized by bipedalism is the defining event of the origins of of immunosuppression. White nose syndrome—an radial cell division when the embryo first forms and the hominins. 3. The replacement model proposes infection in hibernating bats caused by Geomyces a blastopore that becomes the anus. Outpocketing of that modern humans evolved from archaic humans destructans. The disease disturbs their hibernation, the primitive gut forms the coelom. (19.2) 1. Both in Africa. After that, the modern humans migrated making them wake up and use up their fat stores, sponges and cnidarians are multicellular. Sponges to Asia and Europe, where they replaced the archaic resulting in starvation. have a cellular level of organization with no true species already present there. tissues, and they exhibit no symmetry in body form. Testing Yourself Cnidarians have a tissue level of organization with Testing Yourself two germ layers (ectoderm and an endoderm), and 1. a; 2. e; 3. c; 4. a; 5. b; 6. e; 7. d; 8. c; 9. a. anther; they are radially symmetrical. 2. Both sponges 1. b; 2. a; 3. d; 4. b; 5. a; 6. a; 7. a; 8. a; 9. b; 10. d; b. filament; c. stigma; d. style; e. ovary; f. ovule; and cnidarians are multicellular invertebrates. 11. c; 12. a; 13. b; 14. d; 15. b; 16. c g. sepals (calyx); h. petals (corolla); 10. b; 11. b; Sponges have saclike bodies perforated by many 12. a; 13. c; 14. b; 15. e pores through which water enters and circulates Thinking Critically past collar cells before exiting through the osculum. BioNow They lack organized tissues. Cnidarians are radially 1. The recent discoveries support the idea that a symmetrical and have tentacles with cnidocytes. lineage in Africa from primitive to modern humans The garlic, commercial fungicide, hydrogen peroxide, They have either a polyp or medusa body form, existed with branches of this lineage continuing and rubbing alcohol all disrupt normal protein two germ layers, and tissues as adults. 3. Sponges outside Africa. The discovery of new Homo fossils structure by denaturing proteins. These proteins may lack organized tissues and exhibit a cellular level in Asia and Europe would provide more information be the enzymes used by the fungi to break down the of organization. They are regarded as parazoans on the process of human evolution. Efforts at nuts into nutrients that the fungi can absorb. The fungi at the base of the evolutionary tree of animals. expanding the fossil record from Asia, Europe, cannot grow and reproduce without the functional Cnidarians are radially symmetrical, have two germ and Oceania, as well as Africa, especially from enzymes. layers, and exhibit a tissue level organization. They 1 million years ago to relatively recently, should are the first of the eumatazoans. (19.3) 1. The lopho be continued. 2. Animals that are sessile tend to be Thinking Critically portion of the name is derived from a tentacle-like radially symmetrical because their food comes to feeding structure called a lophophore. The trocho them from all directions. There is no need to have 1. The native soil contains mycorrhizal fungi, which portion of the name refers to a larval stage, called anterior and posterior body regions. Animals that have mutualistic relationships with plant roots and a trochophore that is characterized by a distinct move through their environment are bilaterally enhance the growth of plants. 2. Protists, plants, band of cilia. Flatworms, molluscs, and annelids symmetrical, with the anterior portion containing and fungi all belong to domain Eukarya. The protist all share a common evolutionary ancestor that has sensory receptors. This allows the animal to sense ancestors of plants resembled certain green algae, these structures. 2. Flatworms and annelids are and respond to the environment as it travels through possessing chlorophylls a and b and accessory bilaterally symmetrical and have three germ layers. it. 3. Genetic information from DNA sequencing pigments for photosynthesis, storing carbohydrates Flatworms are acoelomates. Annelids are segmented can more specifically identify relationships between as starch, having cellulose in their cell walls, and and have a coelom and a closed circulatory system. animal species than can physical appearance or utilizing an alternation-of-generations life cycle. 3. Flatworms are acoelomates; molluscs and annelids characteristics, which are subject to variations in The protist ancestors of fungi probably resembled are coelomates. (19.4) 1. Roundworms secrete a genetic expression. modern chytrids in having flagellated gametes and spores, a feature that has since been lost in the
B-10 APPENDIX B Answer Key CHAPTER 20 of eudicot roots contains xylem that is arranged in a seed and bud dormancy; cytokinins—promote cell star in the center and transports water and minerals division, prevent aging, and with auxins promote cell Check Your Progress and phloem that is arranged between the arms of the differentiation; abscisic acid—maintains seed and bud star and transports nutrients. The endodermis forms dormancy and closes stomata; ethylene—promotes (20.1) 1. Epidermal tissue, or epidermis, is a layer of a layer that forces water and minerals to pass through fruit ripening and abscission. 3. The hormones are closely packed cells that provides the outer protective the endodermal cells. The pericycle is a layer of cells found in those areas of the plant where they are most covering of a plant. Root hairs, guard cells, and cork inside the endodermis that continue to divide and effective at promoting organized growth that benefits cells are specialized epidermal cells. Ground tissue form lateral roots. The cortex of the root contains the plant. (21.2) 1. Phototropism, which is a positive contains three types of cells. Parenchyma cells are starch granules and may function in food storage. The tropism, is the unidirectional growth of plants toward found in all organs of a plant. They sometimes contain epidermis forms the outer layer of the root, and in a source of light. Thigmotropism is a growth response chloroplasts and carry out photosynthesis, or they have the zone of maturation, its cells may have root hairs. by a plant to touch, whether from an animal, wind, vacuoles used to store the products of photosynthesis. (20.4) 1. Essential nutrients for plants are divided into rocks, or another plant. It can be positive or negative. They help to carry out the functions of a particular macronutrients and micronutrients according to their Gravitropism is a growth response to gravity. Shoots organ. Collenchyma cells have irregular corners and relative concentration in plant tissue. Plants need a exhibit negative gravitropism by growing upward thicker cell walls. They form the internal bulk of larger amount of macronutrients than micronutrients. against gravity, and roots exhibit positive gravitropism leaves, stems, and roots and provide flexible support 2. Macronutrients are C, H, O, P, K, N, S, Ca, Fe (in by growing downward with gravity. 2. Short-day for immature regions of the plant. Sclerenchyma cells some plants), and Mg. 3. The bacteria within root plants flower when the night becomes longer than have a thick secondary wall, are nonliving, and contain nodules fix atmospheric nitrogen, changing it to nitrate a critical length. Long-day plants flower when the lignin. They provide support for mature regions of or ammonium, which the plant can use. The plant night becomes shorter than a critical length. 3. In the the plant. Vascular tissue is xylem or phloem. Xylem provides carbohydrates to the bacteria. The hyphae daytime, more red light is present than far-red light. contains vessel elements and tracheids, and phloem of the mycorrhizal fungi have a large surface area for Inactive phytochrome exposed to red light is converted is made up of sieve-tube members and companion water uptake, and they break down organic matter. The into its active form. In the evening, when far-red light cells. Both types of vascular tissue transport water roots of the plant provide sugars and amino acids to the is more available, the active phytochrome is converted and nutrients as well as provide support for the plant. fungi. These mutualistic relationships are beneficial into its inactive form. This is the mechanism by 2. Xylem transports water and minerals from roots to both the plants and the bacteria or fungi. (20.5) which plants can detect night length. (21.3) 1. Sepals to leaves. Phloem transports organic compounds 1. Transpiration, the evaporation of water at the leaves, protect the bud as the flower develops; petals attract throughout the plant. 3. In roots, epidermal cells may causes water to move in the xylem from the roots pollinators; a stamen consists of anther and filament form root hairs, which increase the surface area of upward throughout the plant. 2. A continuous water and is the “male” portion; a carpel has stigma, style, roots for increased absorption of water and minerals. In column exists in xylem because of water’s properties ovary, and ovules and is the “female” portion. 2. After leaves, epidermal cells can be modified to form guard of cohesion and adhesion. Without a continuous fertilization of haploid egg and sperm, the diploid cells, which surround stomata. These openings regulate water column, transpiration would be unable to pull embryo in the seed goes through mitosis and develops water loss and gas exchange. Trichomes are prickly water from roots to the leaves. 3. Sugar is actively into a sporophyte. The sporophyte produces haploid projections formed by epidermal cells that deter transported into phloem at a source. When water microspores and megaspores by meiosis. Through insect herbivores. The epidermis in the trunk of a tree follows by osmosis, pressure builds and causes the mitosis, the megaspore develops into the female can be replaced by cork, which is a part of the bark. phloem contents to flow toward a sink, where the sugar gametophyte, the embryo sac, which produces the (20.2) 1. The root system is composed of roots, which is transported out of the phloem. egg, and the microspore develops into the male stabilize the plant and are the site of water and mineral gametophyte, the pollen grain, which produces the absorption. The root tips contain an apical meristem Testing Yourself sperm. 3. The seed provides nourishment for the that produces primary growth downward. The shoot embryo, and the coat protects it from desiccation. system is composed of the stem, leaves, flowers, 1. b; 2. c; 3. d; 4. a. terminal bud; b. blade (leaf); It is often enclosed by a fruit. These characteristics and fruit. The stem supports the leaves, transports c. lateral bud; d. node; e. shoot system; f. vascular help the seed stay viable and assist in its dispersal. materials between roots and leaves, and produces new tissues; g. root system; 5. b; 6. d; 7. b; 8. c; 9. c; 10. c; Dispersal of seeds helps plants succeed in their tissue via the apical meristem at the terminal bud. The 11. c; 12. d environments. (21.4) 1. Bulbs, rhizomes, corms, leaves are the main site of photosynthesis, and the buds on tubers, and runners. 2. Propagation of flowers and fruit are organs involved in reproduction. BioNow commercial crops in sterile culture; conservation of 2. A cotyledon is an embryonic leaf present in seeds plants normally harvested in the wild; propagation of flowering plants. In monocots, which have one In this video, xylem tissue from oak and pine was used, of rare species of plants to be put back into the wild. cotyledon, the cotyledon stores some nutrients and acts which is involved in the transport of water and minerals. 3. Pros—GM plants may be more tolerant of salt, as a transfer tissue for nutrients stored elsewhere. In The question was whether the pits in the tracheids, drought, and cold; they may be more disease- and eudicots, which have two cotyledons, the cotyledons which along with vessel elements make up xylem tissue, pest-resistant; they may have improved yields and supply nutrients for developing seedlings. 3. In were small enough to filter salt out of water as it passed nutritional quality; and they may also make products monocot roots, the vascular tissue is arranged in a ring through the xylem. The conclusion was that the pits are of medical importance to humans. Cons—people around the center. In eudicot roots, the vascular tissue not small enough to filter salt out of water. might be allergic to GM plants and have unforeseen is in the center. The xylem forms a star shape and the reactions to them. GM plants could upset the phloem is located between the points of the star. In the Thinking Critically interaction of species and harm the environment. monocot stem, bundles of vascular tissue are scattered throughout, but in eudicots the bundles are arranged 1. There are unique proteins on the surfaces of the Testing Yourself in a ring close to the edge. Leaf veins are parallel in nitrogen-fixing bacteria that the plant recognizes. monocots and form a netlike pattern in eudicots. 2. When the stomata open at night, both CO2 and the 1. d; 2. a; 3. e; 4. a; 5. a; 6. e; 7. b; 8. c; 9. a; 10. b; (20.3) 1. The mesophyll, which is the site of water present in the fog move into the leaves, allowing 11. d; 12. b; 13. e; 14. d; 15. b; 16. d; 17. e photosynthesis, has a large surface area for gas the plant to acquire enough moisture to survive. The exchange and water loss. The leaf contains stomata opening of the stomata at night is an adaption to the dry Thinking Critically for gas exchange and veins that carry nutrients to environment, in which moist fog is present only at night. and from the leaf. Some leaves are broad and thin, 1. When plants are shipped long distances, they providing large surface areas for light absorption and CHAPTER 21 produce ethylene as a result of stress. Ethylene builds gas exchange. The waxy cuticle of the leaf prevents up within the shipping container and the plastic water loss. 2. Wood is secondary xylem made by the Check Your Progress sleeves near the plant, amplifying the abscission vascular cambium. Bark is made up of cork, cork response. 2. You could determine whether flowers cambium, cortex, and phloem. 3. The vascular tissue (21.1) 1. Auxins, gibberellins, cytokinins, or stems are responsible by cutting the flowers off abscisic acid, and ethylene. 2. Auxins—maintain the stems and looking to see whether the stems still apical dominance, involved in phototropism and exhibit sun tracking. If so, then the stems rather than gravitropism, promote root formation and fruit growth; gibberellins—elongation of cells, break
APPENDIX B Answer Key B-11 the flowers are responsible. You could determine brings about constriction of the blood vessels in the that allows for expansion and contraction in response which portion of the stem is responsible for sun skin. If the temperature continues to drop, shivering to pulses of pressure created by the contraction of the tracking by shading different portions of the stem and begins in order to generate heat. With a rise in heart. Capillary walls are composed of an epithelium determining which treatment blocks the response. temperature, blood vessels in the skin dilate and sweat only one cell thick, which allows for the diffusion of 3. Until the problem of acquisition of herbicide glands are activated. gases, nutrients, and wastes in and out of the blood. resistance by johnson grass is resolved, the production Veins have thinner, less elastic walls than arteries. of herbicide-resistant sorghum should be banned. Testing Yourself They have valves and carry blood back to the heart However, in the interim, African farmers should be under relatively low pressure. 3. Blood flows from supported in new ways to manage witchweed in their 1. a. cell; b. tissue; c. organ; d. organ system; the right atrium into the right ventricle and then farming practices so as to ensure their well-being. e. organism; 2. b; 3. a, b; 4. a; 5. c, d; 6. c; 7. a. dendrite; through the pulmonary artery to the lungs. The blood b. cell body; c. nucleus; d. nucleus of Schwann cell; is oxygenated in the capillaries of the lungs and next CHAPTER 22 e. axon 8. d; 9. d; 10. d; 11. c; 12. a; 13. b; 14. e; 15. a passes through the pulmonary vein to the left atrium of the heart. With the contraction of the left atrium, Check Your Progress Thinking Critically the blood flows into the left ventricle and then out through the aorta to the tissues of the body, where it (22.1) 1. A tissue is composed of cells that are of 1. Even though the heart is made of cardiac muscle passes through capillary beds, delivering oxygen to the the same structural and functional type. An organ is instead of skeletal muscle, the link between muscular tissues. Veins receive the blood from the capillaries made up of different tissues, each of which contributes dystrophy and heart disease is that both types and return the blood back to the right atrium via the to the functioning of the whole organ. 2. Epithelial of muscle tissue deteriorate in a similar manner. inferior and superior venae cavae. 4. The lymphatic tissue covers and lines organs and covers the body's 2. Organisms have to interact with the external system takes up fat from the intestines, it works with surface; it forms a barrier that can withstand a high environment to obtain energy and nutrients for growth the immune system, and it takes up excess interstitial amount of wear and tear, and its cells can divide and reproduction, to find shelter, and, sometimes, fluid and returns it to cardiovascular veins via the frequently to renew it. 3. Connective tissue is needed to find mates. These interactions bring the risk of subclavian veins. 5. At the arterial end of a capillary, to hold organs and parts of the body together, giving upsetting the internal environment. However, without higher blood pressure forces water out of the blood. the body structure, support, and protection against interacting with the external environment, many of the In the midsection of the capillary, oxygen and carbon physical damage. 4. Skeletal muscle is striated, functions that define a living organism would be lost. dioxide diffuse across the capillary wall according to is attached to the skeleton to produce movement, Without interaction with the environment, plants could their concentration gradients. At the venous end of the has fibers that are cylindrical and multinucleated, not receive energy from the sun for photosynthesis; capillary, the osmotic pressure inside the capillary is and is under voluntary control. Cardiac muscle animals could not get nutrients from eating food or greater than the blood pressure and water moves back is found in the walls of the heart. Its fibers are sense danger from predators. 3. The advantage of into the blood. (23.3.) 1. Plasma, the liquid portion striated, branched, and uninucleated and are under having tissues, organs, and organ systems is that their of blood, contains salts and proteins that buffer the involuntary control. Smooth muscle is found in functions can be separated, made more specific, and blood and maintain its osmotic pressure. Some of the the walls of the digestive system and other internal made more efficient. Organisms with organ systems plasma proteins are involved in blood clotting and the organs. Its fibers are spindle-shaped, nonstriated, are selected for because they have greater fitness. Just transport of large organic molecules. Nutrients are and uninucleated, and it is under involuntary control. as a large company uses specialized divisions to carry also carried in the plasma. Red blood cells transport 5. Nerves communicate information from sensory out its functions, so animals use specialized organs oxygen to the tissues. White blood cells function to receptors to the spinal cord and brain. There the that work together within a system complementing defend the body against infection. Platelets play a information is integrated and interpreted. Nerves then other systems. 4. Upon death, cells, tissues, organs, role in blood clotting. 2. All white blood cells are conduct impulses to the muscles and glands, causing and organ systems no longer function. Without involved in the immune response. Granular leukocytes a response of contraction or secretion. Information functioning organ systems, the homeostasis that is include neutrophils, which phagocytize pathogens about the external and internal environments is essential to life cannot be maintained. and cellular debris; eosinophils, which digest large coordinated by nervous tissue. (22.2) 1. Organ pathogens, such as worms, and reduce inflammation; systems are composed of organs, which are composed CHAPTER 23 and basophils, which promote blood flow to injured of tissues. The functions of an organ system are tissues during the inflammatory response. Agranular dependent on its organs functioning together. Check Your Progress leukocytes are lymphocytes, which are responsible 2. Both the nervous and endocrine systems coordinate for specific immunity and come in two types (B cells and regulate the functions of other systems in the (23.1) 1. Animals that have all their cells exposed produce antibodies and T cells destroy cancer and body. 3. Cardiovascular—transports nutrients and to water do not need a circulatory system because virus-infected cells), or monocytes, which become gases and removes wastes; lymphatic—absorbs they can adequately exchange gases, obtain nutrients, macrophages that phagocytize pathogens and cellular fat from the digestive system and collects excess and get rid of wastes by diffusion across cell debris. 3. When a blood vessel is damaged, blood interstitial fluid; immune—protects the body from membranes. 2. Both types of circulatory systems containing platelets leaks out. The platelets clump to disease; respiratory—exchanges gases with blood; use a heart to pump fluid. An open system pumps form a plug at the injury site. Platelets and the injured urinary—rids blood of wastes; digestive—receives hemolymph through channels and cavities that open tissue release prothrombin activator, which converts food and digests into nutrient molecules for entry into up to the body cavity. The hemolymph eventually prothrombin to thrombin. Thrombin acts to convert the blood; nervous—receives stimuli and conducts drains back to the heart. A closed system pumps blood fibrinogen to fibrin, which forms threads that trap impulses; endocrine—secretes hormones and through closed vessels that carry blood both away red blood cells to form a clot. Clot retraction follows. regulates functions of other systems; integumentary— from and back to the heart. 3. The pulmonary circuit 4. Hypertension can be treated with medication provides protection and houses sensory receptors; carries blood to and from the lungs, and the systemic and changes in diet and exercise. Atherosclerosis is skeletal—protection, mineral storage, blood cell circuit carries blood to and from the tissues. 4. In a an accumulation of soft masses of fatty materials production, movement; muscular—movement; fish, the blood moves in a single circuit through a beneath the lining of the arteries. Treatments include reproductive—production of sex cells and offspring. heart that has a single atrium and ventricle. In this medication, surgery, and changes in diet and exercise. (22.3) 1. Homeostasis is required to maintain circuit, blood moves through the capillaries of the constant conditions in the internal environment as gills, where gas exchange occurs. In mammals, the Testing Yourself an organism is exposed to varying conditions in the pulmonary and systemic circuits are separate. The external environment. 2. A sensor detects a change heart functions as two coordinated pumps. 1. c; 2. a; 3. d; 4. a. pulmonary vein; b. aorta; c. renal in the internal environment and communicates that (23.2) 1. Phase 1 (atrial systole): the atria contract artery; d. lymphatic vessel; e. pulmonary artery; information to a control center, which initiates an and pass blood to the ventricles. Phase 2 (ventricular f. superior vena cava; g. inferior vena cava; h. hepatic effect that brings conditions back to normal. At that systole): the ventricles contract and blood moves into vein; i. hepatic portal vein; j. renal vein; 5. a; point, the sensor is no longer activated. 3. With a drop the attached arteries. Phase 3 (atrial and ventricular 6. a. superior vena cava; b. aortic semilunar valve; in temperature, the control center (hypothalamus) diastole): both the atria and ventricles relax while the c. pulmonary semilunar valve; d. right atrium; atria fill with blood. 2. Arteries have thick walls with a middle layer of elastic fibers and smooth muscle
B-12 APPENDIX B Answer Key e. tricuspid valve; f. right ventricle; g. inferior vena the water-salt balance of blood, and maintenance of the gallbladder and eventually secreted into the small cava; h. aorta; i. pulmonary trunk; j. pulmonary the acid-base balance of blood. 2. A nephron consists intestine. The pancreas produces pancreatic juice arteries; k. pulmonary veins; l. left atrium; m. bicuspid of the glomerular capsule, which functions in containing sodium bicarbonate and digestive enzymes, valve; n. septum; o. left ventricle; 7. c; 8. d; 9. a; filtration; the proximal convoluted tubule and nephron which is secreted into the small intestine. 4. The 10. c; 11. b; 12. c; 13. b; 14. b; 15. b loop, which function in reabsorption; and the distal salivary glands secrete saliva containing digestive tubule, which functions in secretion. 3. During enzymes into the mouth by way of ducts. This starts BioNow filtration, small molecules such as water, nutrients, the chemical digestion of food. The bile produced salts, and urea move from the blood capillaries into by the liver and stored in the gallbladder enters the The wound was on the neck and involved damage to the glomerular capsule as a result of blood pressure. small intestine and emulsifies fats. The pancreatic the trachea and the carotid artery. Blood flow to the During reabsorption, glucose, amino acids, and other juices enter the small intestine at the duodenum. The head and neck would be severely disrupted. nutrients move from the proximal convoluted tubule bicarbonate neutralizes the chyme, and the enzymes back into the blood capillaries by active transport. break down food molecules. 5. Amylase digests starch Thinking Critically Salts and water are reabsorbed by a combination of to maltose; pepsin hydrolyses proteins to peptides in active transport, osmosis, and protein channels. the stomach; trypsin hydrolyzes proteins to peptides 1. A 20-year-old on his or her birthday has been During secretion, substances such as uric acid, in the small intestine; peptidases digest peptides to alive for (20 years × 365 days/year × 24 hours/day hydrogen ions, ammonia, and penicillin are moved amino acids; lipase digests fat droplets to glycerol × 60 min/day) 1.05 × 107 minutes and experienced from the blood capillaries into the distal convoluted and fatty acids. (25.2) 1. Macronutrients are needed 7.4 × 108 heartbeats. In that lifetime, the individual's tubule by means other than filtration. 4. Water-salt in large quantities to supply energy; they include heart has pumped 5.5 × 107 liters of blood. 2. The balance and pH balance are important to homeostasis carbohydrates, lipids, and proteins. Micronutrients are four-chambered heart keeps O2-poor and O2-rich because blood volume and composition must be stable needed in small quantities and do not supply energy; blood separate. This allows the maximum amount of in order to maintain circulation and proper gas, they include vitamins and minerals such as vitamin oxygen to be delivered to the cells. This in turn allows nutrient, and waste exchange. D and calcium. 2. Junk foods do contain nutrients; for the greatest amount of energy to be produced. A however, their sugar and/or fat content may be out of four-chambered heart works with greater efficiency Testing Yourself proportion to their vitamin and mineral content. They to support the high metabolism of an endothermic may provide just empty calories. 3. Essential nutrients lifestyle. 3. Lower oxygen levels found at higher 1. a. nostril; b. nasal cavity; c. pharynx; d. epiglottis; must be obtained from the diet because the body altitudes stimulate an increased production of red e. glottis; f. larynx; g. trachea; h. bronchus; i. cannot synthesize them or cannot produce them blood cells and hemoglobin. When athletes train at bronchiole; j. alveoli; k. lung; l. diaphragm; 2. a; 3. d; in sufficient quantities to supply its needs. higher altitudes long enough for this to take effect, 4. a; 5. a. kidney; b. ureter; c. bladder; d. urethra; 6. c; (25.3) 1. Carbohydrates, sugars and starches; lipids, they will have the ability to carry a higher amount of 7. d; 8. b; 9. a; 10. d oils; proteins, meat or fish; minerals, vegetables; oxygen in their bloodstream. This effect will continue vitamins, fruits or vegetables; water, beverages. even at lower altitudes for a few months after the high Thinking Critically 2. Consuming too many carbohydrates can lead to altitude training has stopped. More oxygen means obesity, which is associated with type 2 diabetes more energy through aerobic cellular respiration for 1. If the tissues were not receiving much oxygen due and cardiovascular disease; too many lipids can muscle contraction. 4. a. Long-term hypertension to CO binding to hemoglobin, then the cause of death lead to elevated lipid levels and increased risk of damages arteries and increases the likelihood of would be asphyxiation. The tissues would not be cardiovascular disease as well as obesity; too much plaque formation. The heart has to work harder to receiving enough oxygen to carry out cellular protein can lead to increased calcium loss in urine, move the blood. The increased pressure is particularly respiration. 2. If a low-salt diet lowered the high blood formation of kidney stones, and obesity. 3. Without damaging to capillary beds present in the kidneys pressure, that would indicate that the hypertension vitamins and minerals, proper organ development, and in the retina of the eye. b. The plaques that result caused the kidney damage. If a low-salt diet failed to as well as proper protein synthesis and function, from atherosclerosis interfere with blood flow and, lower blood pressure, then it would appear that kidney will not occur. Without enough water, the chemical combined with hypertension, further strain the heart. damage caused the hypertension. 3. Grasshoppers reactions in the body, joint lubrication, nutrient The plaques cause arteries to narrow and harden, have a tracheal system consisting of air tubes to carry transport, and temperature regulation, will be and the tissues supplied by the arteries will get less out gas exchange. Their exoskeleton is both airtight compromised. (25.4) 1. The guidelines released in blood, oxygen, and nutrients. If coronary arteries are and waterproof. They excrete uric acid, which requires 2015 focus on establishing healthy eating patterns for narrowed or blocked, the heart muscle cannot function little water, and their Malphighian tubules absorb most people rather than recommending specific amounts and some of its tissue can die during a heart attack. of the water back into their bodies, which helps them of nutrients. The goals are to promote health, prevent avoid desiccation in dry conditions on land. chronic long-term disease, and help people achieve CHAPTER 24 and maintain a healthy weight. 2. The MyPlate CHAPTER 25 graphic depicts the desired proportions of the five Check Your Progress food groups (fruits, vegetables, grains, protein, and Check Your Progress dairy) for daily consumption. A related website, (24.1) 1. Breathing is the movement of air into the ChooseMyPlate.gov, provides detailed information lungs (inspiration) and out of the lungs (expiration). (25.1) 1. Ingesting food; breaking down food into about each of the food groups and guidance for External exchange of gases occurs between the air and molecules that can be transported; absorbing nutrient following the dietary recommendations. 3. The the blood within the lungs. Internal exchange of gases molecules; eliminating indigestible materials. 2. The \"Nutrition Facts\" label states serving size, servings occurs between blood and interstitial fluid and also small intestine is longer and narrower than the per container, calories per serving, calories from between cells and interstitial fluid. 2. In the upper large intestine. Its folded lining is covered by villi fat (current label), the % daily value in a serving respiratory tract, air enters the nose and moves containing microvilli. The pancreas, liver, and and amounts for fats, cholesterol, sodium, and through the nasal cavities to the pharynx and into gallbladder are connected to the small intestine carbohydrates, the amount of protein, and the % the larynx. From there, the air moves to the lower by ducts. In the small intestine, proteins and daily value (and amounts in proposed label) for some respiratory tract, starting with the trachea, then to carbohydrates are broken down to smaller molecules, vitamins and minerals. The current label recommends the bronchi, bronchioles, and finally the alveoli. and fats are emulsified. The smaller molecules are intake amounts for fat, cholesterol, sodium, and 3. Oxygen follows its concentration gradient as it then absorbed into the microvilli. The large intestine carbohydrate as well as the Calories/gram for each moves from a higher concentration in the lungs to a begins with a cecum to which the appendix is type of macronutrient. The proposed label will lower concentration in the blood. When carbon attached. The large intestine absorbs water, salts, and have a footnote on daily values and caloric values. dioxide from the tissues enters the blood, it combines some vitamins. It houses bacteria that help break (25.5) 1. BMI = 26.1 2. Type 2 diabetes often with water to form carbonic acid, which breaks down down food and produce some vitamins. It stores occurs in people who are obese and have impaired to bicarbonate ion and H+. The H+ binds to the globin indigestible material that is then eliminated at the portion of hemoglobin, and the bicarbonate ion is anus. 3. The duodenum is the first part of the small carried in the plasma. (24.2) 1. The kidney functions intestine and is connected to the pancreas and liver are excretion of nitrogenous wastes, maintenance of by ducts. The liver produces bile, which is stored in
APPENDIX B Answer Key B-13 insulin production and insulin resistance. With become more permeable. More blood moves to the Thinking Critically insulin resistance, cells cannot effectively take up area, and more fluid moves into the tissues. and metabolize glucose. The glucose builds up in Neutrophils and macrophages migrate to the site of 1. The tonsils are composed of lymphatic tissue and the blood and appears in the urine. Obesity can lead injury and phagocytize pathogens. 3. Complement help to capture pathogens as they enter the digestive to cardiovascular disease, which because of the proteins bind to mast cells to trigger histamine and respiratory tracts. Because of their location and buildup of plaque in arteries, leads to hypertension, release, attract phagocytes to the site of injury, bind function, they often contain bacteria or viruses that at heart attack, and stroke. 3. Each person varies in to pathogens already coated with antibodies to times can overwhelm the lymphatic tissue and cause metabolism, activity level, and energy needs, so it is ensure that they are phagocytized, and form a an infection. Either through the body’s usual defenses important to balance your daily energy expenditure membrane attack complex, which produces a hole in or through help from medication, individuals can with your intake of food. the surface of a microbe. These functions usually recover from these infections. The tonsils, “complement” certain immune responses and are once healthy, will again aid the body in the fight Testing Yourself not specific to one pathogen. NK cells kill virus- against infection. Only if they become chronically infected cells and cancer cells, and they are not infected so as to obstruct airways and no longer 1. a. salivary gland; b. mouth; c. liver; d. gallbladder; specific. They bind to cells that have lost their perform their functions should they be removed. e. duodenum; f. cecum; g. appendix; h. anus; ability to make self proteins. Their numbers do not 2. Immunosuppressive drugs dampen the body’s i. pharynx; j. esophagus; k. diaphragm; l. stomach; increase, and they do not recognize antigens from response not only to the transplanted tissue but to m. pancreas; n. large intestine; o. small intestine; previous exposure to them. (26.3) 1. The antibodies other foreign and infected cells as well. Therefore, the p. rectum; 2. b; 3. b; 4. a; 5. d; 6. b; 7. c; 8. a; 9. a; 10. f; produced by plasma cells bind to specific antigens. body’s ability to fight infections is weakened and the 11. e; 12. b; 13. b; 14. c; 15. c; 16. b; 17. a; 18. d Such antigen-antibody complexes mark the antigen transplant patient becomes more susceptible to all for destruction. A person’s immune system becomes types of infections. 3. a. Drug companies have an Thinking Critically adapted to recognize a particular antigen so that the obligation to price their products fairly to avoid person becomes immune to it. 2. B cells are exploitation of consumers. However, they need to 1. Bariatric surgery alters the physical structure and produced and mature in the bone marrow. They give support their operations as well as conduct research therefore the function of the stomach and small rise to plasma cells that produce antibodies. The and development of new pharmaceuticals. intestine. It can lead to incomplete digestion and antigen-antibody complexes are engulfed by Nonetheless, they should not seek excessive profits for malabsorption of nutrients. Protein digestion, which neutrophils or macrophages or may activate their shareholders or excessive compensation for their starts in the stomach and ends in the small intestine, complement. T cells are produced in the bone executives. b. It is best for everyone if patent laws are can be affected as well as the absorption of amino marrow and mature in the thymus as cytotoxic T respected since they provide incentives for businesses acids in the small intestine. The availability of iron, cells, which destroy virus-infected or cancer cells, or to operate and develop new products. However, when vitamin B12, folate, and calcium, and therefore their helper T cells, which regulate immune function. human lives are being lost due to egregious corporate absorption, are often altered by bariatric surgery. 3. The antibody response uses proteins called policies, then governments need to step in and 2. Marketing strategies that focus on selling unhealthful antibodies produced by B cells to fight pathogens. regulate the drug companies. foods to children should be regulated, similar to the way The cellular response uses entire cells, T cells, to advertising of tobacco products and alcohol must fight pathogens. 4. MHC markers are unique to each CHAPTER 27 follow certain regulations. However, because food must individual, except identical twins, and allow the be consumed and not just eliminated, because people immune system to identify self from nonself cells. Check Your Progress have enormous physiological and mental investments in If the MHC markers are nonself, tissue rejection can food, and because marketing tactics are subtle and occur. (26.4) 1. A vaccine is a substance prepared (27.1) 1. Sensory neurons transmit nerve impulses pervasive, innumerable obstacles to regulation of food from a pathogen or its products that, when from sensory receptors to the central nervous system. advertising exist. The advertisements should be introduced into an individual, stimulates the immune Interneurons carry nerve impulses between parts of required to contain an educational component that system to create lasting immunity against the the central nervous system. Motor neurons carry nerve informs the consumer of what the product contains and pathogen. 2. A booster, or second dose of a vaccine, impulses from the central nervous system to muscles how much should be consumed. Due to children being is sometimes needed to stimulate the immune or glands. 2. The cell body contains the nucleus and particularly susceptible to marketing strategies, access response so as to raise the plasma antibody other organelles. Dendrites receive signals from to children’s markets should be restricted. concentration to a level that is effective at fighting sensory receptors or other neurons. An axon is a long the pathogen. 3. Active immunity involves the extension that conducts nerve impulses and is often CHAPTER 26 immune system being exposed to a pathogen or covered by a myelin sheath. 3. First, Na+ gates open, vaccine and responding to it by producing plasma and Na+ moves to the inside of the axon, which Check Your Progress cells and antibodies. Memory cells are also becomes positive, reversing the charge difference produced, ensuring long-term immunity. Passive across the axon membrane. Second, K+ moves to the (26.1) 1. The immune system functions to maintain immunity involves introducing into the body outside, and the inside of the axon becomes negative health by fighting infections and destroying cancer prepared antibodies against a pathogen, ones that the again. 4. Nerve impulses arriving at the axon terminal cells. 2. Red bone marrow—produces all types of individual did not produce. Passive immunity is of the presynaptic cell cause synaptic vesicles to fuse blood cells; thymus—aids in maturation of T temporary. (26.5) 1. Allergies are hypersensitive with the axon membrane and release a lymphocytes and tests their ability to recognize responses of individuals to antigens called allergens, neurotransmitter into the synaptic cleft. The self- versus nonself cells; spleen—filters pathogens which produce the response. 2. An immediate neurotransmitter molecules then diffuse across the and debris from the blood and contains allergic response occurs within seconds of exposure synaptic cleft and bind to receptors in the membrane lymphocytes; lymph nodes—house macrophages to an allergen and is caused by chemicals, including of the postsynaptic cell. 5. The central nervous system that remove pathogens and antigens from lymph and histamine, that are released by mast cells. A delayed consists of the brain (cerebrum, diencephalon, contain lymphocytes. 3. Antigens are protein or allergic response takes longer to develop and is cerebellum, brain stem) and spinal cord. The brain carbohydrate molecules that stimulate the immune probably initiated by memory T cells. 3. An AIDS receives sensory information, integrates it, and sends system to respond to foreign substances, pathogens, patient has a compromised immune system due to out motor instructions to glands and muscles. The and cancer cells. This type of response constitutes the HIV virus living in and destroying helper T spinal cord conducts nerve impulses between the brain immunity. (26.2) 1. Physical barriers include the cells, which are necessary for the activity of all and spinal nerves. 6. A sensory input generates a skin with its sweat and oil glands and the mucous other immune system cells. nerve impulse that moves along sensory axons to the membranes of the respiratory, digestive, spinal cord. The signal is passed on to many reproductive, and urinary tracts. The acidity of the Testing Yourself interneurons, some of which synapse with motor stomach inactivates or kills harmful bacteria. neurons. The nerve impulses travel along the axons of Bacteria that reside in the large intestine and vagina 1. a; 2. c; 3. a; 4. b; 5. e; 6. e; 7. c; 8. e; 9. b; 10. a; the motor neurons to an effector, which brings about a prevent pathogenic organisms from becoming 11. a; 12. e; 13. d; 14. b; 15. e; 16. b; 17. b; 18. c response to the stimulus. Other interneurons carry established there. 2. Damaged cells and mast cells release chemicals that cause capillaries to dilate and
B-14 APPENDIX B Answer Key nerve impulses to the brain, which results in the pressure in an environment with scarce food, like that and pull them toward the center of the sarcomere. sensation of the stimulus. 7. The parasympathetic on Borneo, would tend to sacrifice brain size to Then ATP allows the heads to be released, and they division \"keeps house” by automatically and conserve energy. In an environment with plentiful reattach at a new location along the actin filament, involuntarily maintaining the internal responses food like Sumatra, the orangutans can afford to spend resulting in contraction or shortening of the muscle. associated with a relaxed state, such as pupil extra energy on nervous tissue, and thus reap the contraction, food digestion, and slow heartbeat. advantage of larger brain size. 4. Extreme shortness Testing Yourself (27.2) 1. Steroid hormones enter the cell through the has been found to limit a person’s ability to succeed in plasma membrane, bind to a receptor within the cell, many ways, so giving hGH to extremely short people 1. b; 2. b; 3. d; 4. e; 5. c; 6. b; 7. a; 8. a. cochlear and then move to the nucleus to stimulate genes to can be supported. However, defining \"extreme nerve; b. cochlea; c. tympanic membrane; d. auditory produce proteins that alter cell activity. Peptide shortness\" is necessary. The FDA should set the limits tube; e. auditory canal; f. ossicles; g. semicircular hormones bind to a receptor in the plasma membrane, of the normal range for height and decide at what canals; h. outer ear; i. middle ear; j. inner ear; which then induces a signal transduction pathway height it is acceptable to administer hGH. Without 9. a. sclera; b. retina; c. vein; d. artery; e. optic nerve; leading to the creation of a second messenger, which such regulations, it is likely that hGH will be misused. f. fovea; g. ciliary muscle; h. iris; i. pupil; j. lens; affects the metabolism of the cell. 2. The 5. It is natural to want to avoid death and improve k. cornea; 10. c; 11. a; 12. a; 13. c; 14. c; 15. a hypothalamus is a part of the brain. It receives sensory performance; however, the use of hGH has too many information about the internal environment of the negative side effects, the injections are very expensive, Thinking Critically body and communicates with the autonomic nervous and the hormone should be considered a drug that system to maintain homeostasis. It also contains falls under the anti-doping rules applied to 1. The blood vessels interfere with the transmission of hormone-secreting neurons that control the glandular competitive athletes. Though one is tempted to control light to the back of the retina, consequently impairing secretions of the pituitary gland. 3. In a negative- one’s fate, it is better to accept aging as a natural part the signals sent to the brain. Both cancer and these eye feedback mechanism, a hormone controls the level of of life than to use hGH to postpone the inevitable. diseases involve the uncontrolled growth of new blood a product. When that level varies from normal, the vessels. Anti-angiogenesis drugs that have been amount of hormone, whether too much or too little, is CHAPTER 28 developed for cancer treatment are currently being altered until the product’s level returns to normal. studied for the treatment of these eye diseases. 2. Our 4. The hypothalamus controls the release and Check Your Progress olfactory system allows us to recognize and inhibition of hormones in the pituitary gland. The discriminate among many different odors. Therefore, anterior pituitary gland releases gonadotropic (28.1) 1. Chemoreceptors detect chemicals in the we can detect the difference between a dangerous hormones, TSH, ACTH, prolactin, and GH, and the environment that are interpreted as tastes and smells. odor, such as smoke, and a harmless one, such as the posterior pituitary gland releases ADH and oxytocin. Mechanoreceptors detect mechanical signals involved fragrance of a flower. On the other hand, every natural The thyroid gland releases thyroxine, triiodothyronine, in hearing and balance. Photoreceptors detect light toxin tastes bitter, so it is more important to be able to and calcitonin. The parathyroid gland releases PTH. involved in sight. Cutaneous receptors detect touch, sense bitterness than to be able to discriminate The adrenal medulla releases epinephrine and pain, temperature, and pressure. Nociceptors are pain between bitter tastes. Therefore, humans have evolved norepinephrine, and the adrenal cortex releases receptors that detect extremes in temperature and to identify bitter compounds by the taste while not aldosterone and cortisol. The pancreas releases insulin pressure and chemicals released by damaged tissue. being able to distinguish between the different and glucagon. 5. Hormones are chemical messengers Proprioceptors detect changes in positions of joints, compounds. that are released by a gland and regulate the activity of muscles, and bones. 2. Sensors in the skin provide another organ, tissue, or gland. Often two hormones act sensory input that is communicated to the primary CHAPTER 29 together to maintain a constant internal environment. sensory area of the cerebral cortex. In the epidermis, One hormone raises the level of the response and the free nerve endings respond to cold and warmth as well Check Your Progress other lowers it, creating a stable balance. as pain. The dermis contains sensory receptors for pressure and touch, including the Pacinian corpuscle (29.1) 1. Asexual reproduction occurs when one Testing Yourself and root hair plexus. 3. The eyes have sensory parent produces offspring that are genetically identical receptors sensitive to light. These photoreceptors to each other and to the parent. Sexual reproduction 1. d; 2. a; 3. c; 4. d; 5. c; 6. d; 7. a; 8. d; 9. b; 10. b; detect the amount of light, the direction from which it involves two parents, and the offspring have different 11. b; 12. b is coming, and the wavelength which is interpreted as combinations of the parents’ genes. 2. Animals that color. Human ears detect sound pressure waves, the reproduce in the water have no need to protect their BioNow head’s position relative to gravity, and the rotational eggs and embryos from drying out, but they do have movement of the head. (28.2) 1. Bones and muscles to worry more about predators destroying the zygotes. Increasing the temperature to 60°F and the length of together support the body, allow body parts to move, Animals that reproduce on land need to protect their daylight to 16 hours triggered the hypothalamus in the protect internal organs, and help other systems, such gametes and embryos from desiccation while quails to produce releasing hormones that stimulate as the respiratory system, to function. Contraction of providing a stable environment for development. the anterior pituitary to produce FSH and LH, which skeletal muscle helps to move blood and lymph 3. Egg-laying animals are oviparous. Animals that stimulate the testes to make sperm and the ovaries to through their vessels. Skeletal muscle contraction retain their eggs in the body until hatching has make eggs. Release of androgens by the testes and generates heat, which helps to maintain body occurred are ovoviviparous. Mammals that produce estrogen and progesterone by the ovaries likely temperature. The skeleton stores fat and calcium. living young are viviparous. (29.2) 1. Sperm are triggered mating behavior in the birds. 2. The axial skeleton is composed of the skull, produced in the seminiferous tubules in the testis, vertebral column, ribs, and sternum and lies along the mature in the epididymis, are propelled into the vas Thinking Critically midline of the body. The appendicular skeleton is deferens, and travel out through the penis. 2. Testosterone located more laterally and is composed of the shoulder is the main sex hormone in males and is essential for 1. Parkinson’s patients do not exhibit normal girdle, the pelvic girdle, and their attached the normal development and functioning of male sex constriction of blood vessels, so their blood pressure appendages. 3. The middle part of long bones is a organs. It is necessary for the maturation of sperm and slowly decreases. The loss of function of the cavity surrounded by compact bone. This structure maintaining male secondary sex characteristics. sympathetic division prevents the body from provides strength as well as some flexibility to support 3. During the follicular phase of the ovarian cycle, regulating blood pressure, so rapid changes in blood the body and tolerate the stresses put on bone by FSH released by the anterior pituitary promotes the pressure can occur upon standing, leading to muscle contraction. The red bone marrow in the maturation of follicles in the ovary. Ovarian follicles orthostatic hypotension. 2. Type 1 diabetes is thought spongy bone located at the ends of long bones is the produce increasing levels of estrogen, which exert to result when an environmental agent, such as a virus, site of blood cell formation. Articular cartilage located feedback control over FSH secretion, resulting in causes T cells to destroy the pancreatic islets. on the end surfaces of long bones allows these bones ovulation. 4. After ovulation and during the luteal Vaccines may introduce that agent and stimulate the to slide over other bones at the joints. 4. The globular phase of the ovarian cycle, LH promotes the autoimmune response. 3. The brain is an energetically heads of myosin molecules attach to actin filaments development of a corpus luteum. This structure expensive organ, accounting for a substantial produces increasing levels of progesterone, which proportion of our daily calorie intake. The selective causes the endometrium to become secretory.
APPENDIX B Answer Key B-15 Menstruation begins when progesterone production to pass her genes on to future generations, thus (30.4) 1. Opportunistic species are small, have a short declines to a low level. During the follicular phase, increasing her fitness. Since men were not the main life span, are fast to mature, have many offspring, and FSH promotes the development of ovarian follicles caregivers for their children, their fitness would not be take little or no care of their offspring. They exhibit which produce estrogens that cause the endometrium increased if spermatogenesis stopped later in life. exponential population growth, and populations are to thicken. 5. Artificial insemination by donor 3. The villi of the chorion of the embryo are numerous regulated by density-independent effects. Equilibrium (AID)—sperm from a donor is placed in the vagina by and spread through the developing placenta. species are large, have a long life span, are slow to a physician. In vitro fertilization (IVF)—immature Removing a small portion of them for analysis of the mature, have few offspring, and care for the offspring. eggs are removed from the ovaries and cultured fetal cells is not known to harm the fetus. 4. Human They exhibit logistic population growth, regulated by outside the body. When mature, concentrated sperm is chorionic gonadotropin (hCG) is secreted by the density-dependent factors, and populations remain added to the eggs. After a few days, the embryos that placenta as it begins to form. It maintains the near carrying capacity. 2. Extinction is the total have developed are transferred to the uterus. endometrium until enough estrogen and progesterone disappearance of a species or higher group of Intracytoplasmic sperm injection (ICSI)—a single are produced by the placenta. Because hCG is a organisms. 3. Long time to maturity; few offspring sperm is injected into an egg outside the body. The hormone, it is transported in the blood and is removed produced; restricted geographic range; narrow habitat embryo is cultured and eventually transferred to the from the blood into the urine by the kidneys. 5. In tolerance; small size of local populations. uterus. Gamete intrafallopian transfer (GIFT)—the addition to sperm counts, information about eggs and sperm are brought together and then individuals' ages, where they live, and their eating, Testing Yourself immediately placed in the uterine tubes. 6. STDs drinking, and smoking habits, sleep patterns, clothing, caused by bacteria include chlamydia, gonorrhea, and and environmental exposures would be useful in 1. d; 2. b; 3. a; 4. c; 5. d; 6. b; 7. b; 8. a. increasing; syphilis. STDs caused by a virus include HIV, genital forming a testable hypothesis. b. decreasing; c. stable; 9. a; 10. a; 11. d; 12. b; 13. c; warts, genital herpes, and hepatitis. Trichomonas is 14. a; 15. c caused by a parasitic protozoan. (29.3) 1. Mammals CHAPTER 30 develop extraembryonic membranes, or membranes Thinking Critically outside the embryo. The developing embryo depends Check Your Progress on these membranes for protection and nourishment. 1. Population growth rate = 1.1%; doubling time = The chorion, which becomes part of the placenta, is an (30.1) 1. Organism, species, population, community, 62.7 years; 172.5 years if birthrate drops. 2. As the example. 2. During gastrulation, three primary germ ecosystem, biosphere. 2. An ecosystem consists of a numbers of rabbits and pheasants decrease, the impact layers develop: ectoderm, endoderm, and mesoderm. community of living organisms as well as their of predation by red-tailed hawks also decreases. This 3. During gastrulation, cells migrate to become germ physical environment. A community consists of all the is a density-dependent effect. Killing off the hawks layers, forming ectoderm, endoderm, and mesoderm. various populations in a particular locale. 3. Ecology will not bring back the rabbit and pheasant Neurulation occurs after the formation of the is the scientific study of the interactions of organisms populations. 3. The number of surviving individuals notochord. The neural plate thickens, then folds to with each other and their physical environment. (30.2) and a measurement of the variable being studied. In form a neural tube, the anterior portion of which 1. (18.5 – 9.8)/1,000 × 100 = 0.87%; 2. MDCs such as Figure 15.2, that variable is clutch size. 4. a. It can be becomes the brain and the posterior portion the spinal those in Europe and North America have modest argued that the species with the highest risk of cord. 4. Embryonic development occurs during the population growth and a fairly high standard of living. extinction are less successful products of evolution first two months after fertilization and is characterized LDCs such as those in Latin America, Asia, and and should not receive extraordinary protection, which by the establishment of organ systems. Fetal Africa have rapid population growth, and most of the uses up limited resources. However, this position development occurs during the third through ninth people live in poverty. 3. Replacement reproduction assumes humans can place value on a particular month and is characterized by an increase in size. occurs when reproduction in a population results in no species’ existence in an impartial manner. Often big 5. The placenta has a fetal side and a maternal side, population growth. Due to mortality, this occurs when animals with cute faces are given preference. and exchange of molecules occurs between the sides the replacement rate is slightly greater than two b. Determining which species are successful products during development. Carbon dioxide and wastes move children per couple. 4. MDCs strain available of evolution is subjective and therefore inexact. A from the fetal side to the maternal side, and nutrients resources due to high resource consumption, which more cautious approach would be to treat species in and oxygen move from the maternal side to the fetal leads to the production of more hazardous waste. risk of extinction equally, distributing limited side. Maternal blood and fetal blood do not mix. LDCs strain available resources due to large resources between them all. population growth rates. (30.3) 1. An age-structure Testing Yourself diagram shows different numbers of individuals in CHAPTER 31 each age class as a stacked set of bars. Large numbers 1. d; 2. b; 3. a. ureter; b. bladder; c. vas deferens; of prereproductive and reproductive individuals Check Your Progress d. seminal vesicle; e. ejaculatory duct; f. prostate gland; compared to postreproductive individuals indicate that g. bulbourethral gland; h. urethra; i. epididymis; the population will increase. The smaller the relative (31.1) 1. Flowers and pollinators have coevolved to be j. penis; k. foreskin; l. testis; m. scrotum; 4. a. uterine number of individuals who will or can reproduce, the suited to one another. Hummingbirds pollinate red tube; b. ovary; c. rectum; d. cervix; e. bladder; more likely that the population will be stable or flowers that they can see, and the flower petals are f. vagina; g. urethra; 5. d; 6. d; 7. b; 8. a; 9. a; 10. c; decrease. 2. Populations with a type I survivorship specifically curved so that the stamens dust the bird’s 11. a; 12. b; 13. d curve have fewer offspring and most of those head, resulting in the spread of pollen. 2. Species offspring live to reproduce. Populations with a type III richness is the list of species in a community (species Thinking Critically curve have large numbers of offspring and most of composition), while species diversity encompasses them will die before they reproduce. Members of species richness, distribution, and relative abundance. 1. Fetuses and infants place a high caloric toll on their populations with a type II curve have the same chance 3. Primary succession occurs where soil has not yet mothers. Mothers with low percentages of body fat of death at all ages. 3. Both curves plot number of been formed, while secondary succession begins once might starve during pregnancy or during the organisms versus time. Exponential growth produces a soil is present. 4. Competition, predation, parasitism, prolonged period of breast-feeding. They would be J-shaped curve and occurs when resources are commensalism, mutualism. (31.2) 1. Autotrophs take less successful at surviving and producing healthy unlimited. Logistic growth produces an S-shaped in only inorganic nutrients and acquire energy from an children. If the reproductive cycle halts when the body curve and occurs after exponential growth, when outside source, most often the sun. Heterotrophs has insufficient fat reserves, a woman will be better resources become restricted. 4. Density-independent acquire energy from consuming preformed organic able to survive to a time when conditions are more factors include weather and natural disasters such as nutrients. 2. Energy flows from the sun to the Earth favorable for reproduction. 2. One hypothesis is that flooding, tornadoes, and wildfires that can cause and then through living organisms until it is lost as menopause in women developed early in human injury and death. 5. As population density increases, heat. Chemicals cycle throughout the environment, evolution. It allowed women to channel their efforts there are increased levels of competition for limited through both living and nonliving components. 3. A into caring for their existing children and resources and higher levels of predation. Each food chain depicts a single path of energy flow in an grandchildren, increasing the survival rate of the next individual competes to obtain a share of the resources. ecosystem by displaying feeding relationships. An generation. This would give a woman the best chance ecological pyramid depicts the flow of energy between successive trophic levels. 4. Phosphorus—mining ore,
B-16 APPENDIX B Answer Key fertilizing, animal feed supplements, detergents, CHAPTER 32 Hydropower: Dams which disrupt river ecosystems animal waste, and sewage discharge leading to runoff, must be constructed. Geothermal energy: There is a eutrophication, and algal blooms. Nitrogen—making Check Your Progress large capital expenditure associated with the collection fertilizers, leading to runoff; deforestation leading to of geothermal energy, its storage, and its distribution. loss of nitrogen to groundwater; groundwater (32.1) 1. Because conservation biology has the broad Solar energy: Solar collection systems that can convert contamination by nitrates, leading to health problems. focus of conserving natural resources while and effectively store solar energy before distribution Carbon—excess CO2 release into the atmosphere by maintaining biodiversity, it draws on many subfields are costly. (32.4) 1. Characteristics of a sustainable burning fossil fuels, and deforestation, leading to less of basic biology, including genetics, physiology, society include use of renewable energy sources, reuse carbon fixation. (31.3) 1. The biosphere is divided behavior, systematics, ecology, field biology, and of heat and waste materials, and maximal recycling of into aquatic and terrestrial ecosystems. Aquatic evolutionary biology. Applied biology subfields such materials. 2. Plant cover crops, practice multiuse ecosystems include freshwater and saltwater systems. as biopark management, forestry, veterinary science, farming, replenish soil nutrients, conserve water, plant Terrestrial ecosystems can be divided into several fisheries biology, range management, agronomy, and cultivars, use precision farming, use integrated pest major types depending on temperature and rainfall. wildlife management are also used in conservation management, plant a variety of species, plant 2. Tropical rain forest, savanna, desert, temperate biology. 2. Biodiversity is good for the Earth and multipurpose trees, maintain and restore wetlands, use deciduous forest, temperate grasslands (prairie), taiga, therefore good for humans. Extinctions are renewable forms of energy, and buy locally. 3. Create tundra. 3. Swamps have a more concentrated supply of undesirable. Interactions within ecosystems support energy-efficient transportation systems, utilize green organic nutrients and more decomposers than do open biodiversity and are beneficial to humans. Biodiversity roofs, create greenbelts, use solar or geothermal oceans and therefore have a higher primary is the result of evolutionary change and has great energy to heat buildings, improve storm-water productivity. value to humans. (32.2) 1. Direct values include management, plant native species, revitalize old development of medicines, agriculture management, sections of the city before developing new sections, Testing Yourself and products that humans consume. Indirect values change lighting, reduce noise levels, and promote include contributions to biogeochemical cycles, waste sustainable building practices. 1. a; 2. e; 3. a; 4. c; 5. b; 6. d; 7. c; 8. a. energy; disposal mechanisms, provision of fresh water, b. nutrients; c. heat; d. heat; e. producers; f. consumers; prevention of soil erosion, regulation of climate, and Testing Yourself g. inorganic nutrients; h. decomposers; i. heat; ecotourism. 2. Most modern medicines are derived 9. c; 10. d; 11. a. top carnivores; b. carnivores; from organisms, so more biodiversity increases the 1. e; 2. a; 3. e; 4. c; 5. b; 6. d; 7. c; 8. a; 9. b; 10. a; c. herbivores; d. producers; 12. b; 13. a; 14. a potential of developing more medicines. In 11. use more renewable resources than nonrenewable agriculture, biodiversity can lead to the development resources, increase recycling, refine processing to use BioNow of crop varieties able to live in varied climates, fewer materials, and reduce waste materials and heat requiring less fertilizer and water, and able to production; 12. c The exotic species, reed canary grass, outcompeted withstand herbivores more successfully. 3. Biodiversity the native species for resources and took over the gives us flexibility by providing options if any Thinking Critically field. Contributing to this outcome is the fact that resource, whether it is water, land, food, or energy, alien species often do not have natural predators such becomes limited. If there are high levels of biodiversity, 1. Positive environmental impacts include increasing as insects, that limit their growth and reproduction. it may be possible to substitute another species adapted the diversity of animals and plants by increasing Because the reed canary grass comes to dominate the to the altered environment. (32.3) 1. Renewable seasonal flooding and nutrient deposition. The field and be the only plant species present, it lowers resources like solar energy, wind, hydropower, and negative environmental impacts include the biodiversity of consumers (such as insects) present geothermal are unlimited in supply. More will be miscalculation of the economic impacts and the there. With just one grass species present, consumers available as they are used. Nonrenewable resources potential of introducing invasive species. The direct have limited choices for food and habitat and the such as land, fossil fuels, and minerals are limited in benefits for residents include removing them from the variety of species able to live in the field is reduced. supply and can be exhausted. 2. Deforestation occurs economic and personal threat of floodplain residency. when humans harvest timber, clear the forest to create The indirect benefits for residents include those Thinking Critically cropland, or settle in the forest. The thin poor soil is provided by the diversity the Emiquon Refuge can not well suited for farming and is quickly abandoned. offer. 2. How rare the species is, how difficult it will 1. Insects that are best adapted for obtaining the most Increased erosion and runoff result. Desertification be to preserve it, the cost of preserving it, the potential food from flowers that they can easily access occurs when humans convert semiarid land to desert, medicinal benefit to humans. 3. The internal reproduce more. Those flowers best adapted for usually by overgrazing. The loss of vegetation temperature of mammals must stay within a narrow attracting insect pollinators produce more offspring in increases runoff, depletes groundwater, and eventually normal range. As global change leads to climate the next generation, and likewise those insects that leads to desert conditions that force the population to warming in the tropics, the external temperature could obtain the most food produce more offspring than move on. 3. Irrigation depletes water tables. become too high for the homeostatic mechanisms in others. This process continues over generations and Monoculture reduces biodiversity. Application of mammals to control their internal temperature. If the leads to the coevolution of specific adaptations. 2. The fertilizer, herbicides, and pesticides results in runoff core temperature of the mammals rises above normal, otter population is reduced; sea urchin population into water sources. Excessive amounts of fossil fuels they will die off. 4. Steps that can reduce one's rises; kelp plants are reduced; species living in the are used. Converting land to fields results in habitat ecological footprint include adopting a plant-based kelp forests are reduced or eliminated due to habitat destruction. 4. The \"green revolution\" increased crop diet composed of local foods, reducing food waste, destruction; productivity of the kelp forest is reduced yields by introducing new varieties of crops, which led driving a smaller and more fuel-efficient car, using because of fewer producers and consumers; less food to an increased world food supply. Increasing the food trains and buses, flying less, living in a smaller and is being produced and the food chain is weakened; supply is necessary to keep pace with the more energy-efficient dwelling, reducing the number chemical cycling is reduced. 3. Native populations exponentially growing human population. However, of material items purchased, recycling of all types of need to be protected in order to preserve the species the new varieties require increased amounts of materials, and composting. richness and biodiversity of ecosystems. The argument fertilizers, pesticides, and water, impacting the that the mute swan should be allowed to displace environment negatively. 5. Wind power: Land must be native birds is fallacious if that argument is based on a committed to the construction of windmills. human perception of beauty rather than on the health of the community or ecosystem.
Glossary A adhesion Ability of water molecules to be attracted to, amphibian Member of a class of vertebrates that GLOSSARY or cling to, a polar surface, such as the inside of a include frogs, toads, and salamanders and that are abscisic acid Plant hormone that causes stomata to transport vessel (capillary). tied to a watery environment for reproduction. close and initiates and maintains dormancy. adhesion junction Junction between cells in which the analogous structure Structure that has a similar abscission Dropping of leaves, fruits, or flowers from adjacent plasma membranes do not touch but are function in separate lineages but differs in anatomy a plant. held together by intercellular filaments attached to and ancestry. button-like thickenings. abstinence Method of birth control; the practice of not analogy Similarity of characteristics due to convergent engaging in sexual intercourse. adrenal cortex Outer portion of the adrenal gland; evolution. produces the glucocorticoid and mineralocorticoid acetyl-CoA Molecule made up of a 2-carbon acetyl hormones. anaphase Mitotic phase during which daughter group attached to coenzyme A. During cellular chromosomes move toward the poles of the respiration, the acetyl group enters the citric acid adrenal gland Gland that lies atop a kidney. The spindle. cycle for further breakdown. adrenal medulla produces the hormones epinephrine and norepinephrine, and the adrenal cortex produces angiogenesis Formation of new blood vessels. acid Molecule tending to raise the hydrogen ion the glucocorticoid and mineralocorticoid hormones. angiosperm Flowering plant. The seeds are borne concentration in a solution and to lower its pH numerically. adrenal medulla Inner portion of the adrenal gland; within a fruit. secretes the hormones epinephrine and norepinephrine. animal Multicellular, heterotrophic organism belonging acoelomate Animal without a coelom, as in flatworms. acquired immunodeficiency syndrome adult stem cell Cell that can be found in many organs to the kingdom Animalia. in an adult body and that may differentiate to form annelid A segmented worm, such as an earthworm or a (AIDS) Disease caused by a retrovirus and other cell types. transmitted via body fluids; characterized by failure clam worm. of the immune system. age structure In demographics, the distribution of annual ring Layer of wood (secondary xylem) usually actin Muscle protein making up the thin filaments in various age groups in a given population, typically a sarcomere. Its movement shortens the sarcomere, displayed on a bar diagram called an age-structure produced during one growing season. yielding muscle contraction. Actin filaments play a diagram. A growing population has a pyramid- anorexia nervosa Eating disorder characterized by an role in the movement of the cell and its organelles. shaped diagram. actin filament Cytoskeletal filament in eukaryotic cells irrational fear of getting fat. composed of the protein actin; also refers to the thin agglutination Clumping of red blood cells due to a anterior pituitary Portion of the pituitary gland that filaments of muscle cells. reaction between antigens on red blood cell plasma action potential Electrochemical changes that take membranes and antibodies in the plasma. is controlled by the hypothalamus. It produces six place across the axon’s membrane; the nerve impulse. types of hormones, some of which control other active immunity Resistance to disease due to the algae (sing., alga) Type of protist that carries on endocrine glands. immune system’s response to a microorganism or a photosynthesis. Single-celled forms are a part of anther In flowering plants, pollen-bearing portion of vaccine. phytoplankton, and multicellular forms are called the stamen. active site Region on the surface of an enzyme where seaweed. anthropoids Group of primates that includes monkeys, the substrate binds and where the reaction occurs. apes, and humans. active transport Use of a plasma membrane carrier allele Alternative form of a gene. Alleles occur at the antibody Protein produced in response to the presence protein to move a molecule or an ion from a same locus on homologous chromosomes. of an antigen. Each antibody combines with a region of lower concentration to one of higher specific antigen. concentration. Active transport opposes equilibrium allergen Foreign substance (antigen) capable of anticodon Three-base sequence in a transfer RNA and requires energy. stimulating an allergic response. molecule base that pairs with a complementary adaptation A modification in an organism’s structure, codon in mRNA. function, or behavior suitable to the environment. allergy Hypersensitivity to a substance in the antigen Foreign substance, usually a protein or adaptive immunity Form of immunity that involves B environment that ordinarily would not cause an carbohydrate molecule, that stimulates the immune and T lymphocytes in targeting specific pathogens immune reaction. system to react, often by producing antibodies. in the body. antigen-presenting cell (APC) Cell that displays an adaptive radiation Rapid evolution of several species allopatric speciation Origin of new species due to antigen to certain cells of the immune system, so from a common ancestor as populations move into geographic separation of populations. that they can defend the body against that antigen. new ecological or geographical zones. antioxidant Substance, such as vitamin A, C, or E, that Addison disease Condition resulting from a deficiency alternation of generations Pattern that is characteristic defends the body against free radicals. of adrenal cortex hormones; characterized by low of the life cycle of plants, in which a diploid anus Outlet of the digestive tract at the end of the anal blood glucose, weight loss, and weakness. sporophyte alternates with a haploid gametophyte. canal. adenine (A) One of four nitrogen-containing bases in aorta In humans, the major systemic artery that takes nucleotides composing the structure of DNA and alternative mRNA processing Mechanism that allows blood from the heart to the tissues. RNA. Pairs with thymine in DNA and uracil in RNA. cells to produce multiple proteins from the same aortic body Structure located in the walls of the adenosine triphosphate (ATP) Nucleotide with gene by changing the way exons are spliced together. aorta; contains chemoreceptors sensitive to three phosphate groups. The breakdown of ATP hydrogen ion and carbon dioxide concentrations into ADP + Pi makes energy available for energy- alveolus (pl., alveoli) In humans, terminal, microscopic in the blood. requiring processes in cells. air sac in the lungs. apical dominance Influence of a terminal bud in suppressing the growth of lateral buds. Alzheimer disease Brain disorder characterized by a apical meristem In vascular plants, masses of cells in progressive loss of memory, particularly for recent the root and shoot that develops into the epidermal, events. ground, and vascular tissues of a plant. amino acid Organic molecule composed of an amino G-1 group and an acid group; covalently bonds to produce peptide molecules. amniocentesis Procedure for removing amniotic fluid surrounding the developing fetus for testing of the fluid or fetal cells in it.
G-2 Glossary apoptosis Programmed cell death involving a cascade auxin Plant hormone regulating growth, particularly biological species concept Definition of a species of specific cellular events, leading to death and cell elongation; also called indoleacetic acid (IAA). that states that members of a species interbreed and destruction of the cell. have a shared gene pool and that each species is AV (atrioventricular) node Small region of cardiac reproductively isolated from other species. appendicular skeleton Part of the vertebrate skeleton muscle tissue that transmits impulses received from containing the bones of the pectoral girdle and pelvic the SA node to the ventricular walls. biology Scientific study of life. girdle and their attached limbs. biomass Number of organisms of a particular type axial skeleton Part of the vertebrate skeleton forming appendix In humans, small, tubular appendage the vertical support or axis, including the skull, rib multiplied by their weight. containing lymphatic tissue, that extends outward cage, and vertebral column. bioremediation Cleanup of the environment using from the cecum of the large intestine; may play a role in fighting infections. axon Elongated portion of a neuron that conducts bacteria to break down pollutants, such as oil spills. nerve impulses, typically from the cell body to the biosphere Zone of air, land, and water at the surface aquatic ecosystem Freshwater ecosystem (river, synapse. stream, lake, pond) or saltwater (marine) ecosystem of the Earth in which organisms are found; (ocean, coral reef, saltwater marsh). B encompasses all the ecosystems on Earth. biotechnology Genetic engineering and other aquifer Rock layers that contain water and release it in B lymphocyte (B cell) Lymphocyte that matures techniques that make use of natural biological appreciable quantities to wells or springs. in the bone marrow and, when stimulated by the systems to create a product or achieve a particular presence of a specific antigen, gives rise to antibody- result desired by humans. arachnids Group of arthropods that includes spiders, producing plasma cells. biotic potential Maximum growth rate of a population scorpions, mites, harvestmen, and ticks. under ideal conditions. B-cell receptor (BCR) Complex on the surface of a B bipedalism Walking erect on two feet. archaea Prokaryotic members of the domain Archaea. cell that binds an antigen and stimulates the B cell. bird Endothermic reptile that has feathers and wings, is Many live in unique habitats, such as swamps, highly often adapted for flight, and lays hard-shelled eggs. saline environments, and submarine thermal vents. bacteria Prokaryotic members of the domain Bacteria; birth control pill Oral contraceptive containing most diverse and prevalent organisms on Earth. estrogen and progesterone. arteriole Vessel that takes blood from an artery to bivalve Type of mollusc with a shell composed of capillaries. bacteriophage Virus that reproduces in a bacterium; two valves; includes clams, oysters, mussels, and often referred to as a phage. scallops. artery Blood vessel that transports blood away from blastocyst Early stage of animal embryonic the heart. ball-and-socket joint Synovial joint (at hip or development that consists of a hollow, fluid-filled shoulder) that allows movement in all directions. ball of cells. arthropods Invertebrates with an exoskeleton and blood Fluid connective tissue that is composed of jointed appendages, such as crustaceans and insects. bark External covering of a tree stem, containing cork, several types of cells suspended in plasma and is cork cambium, cortex, and phloem. circulated by the heart through a closed system of artificial selection Selection by breeders of individual vessels. organisms with particular traits, or combinations of base Molecule tending to lower the hydrogen ion blood pressure Force of blood pushing against the traits, over others lacking the traits. concentration in a solution and raise the pH inside wall of blood vessels. numerically. body mass index (BMI) A calculated number used to asexual reproduction Form of reproduction that does determine whether or not a person is overweight or not require two individuals; example is binary benign tumor Tumor that does not invade adjacent obese. fission in bacteria. tissue and stays at the site of origin. bolus Mass of chewed food mixed with saliva. bone Connective tissue having collagen fibers and an atherosclerosis Form of cardiovascular disease bicarbonate ion Ion that participates in buffering the extremely hard matrix of inorganic salts, notably characterized by the buildup of cholesterol and fatty blood, and the form in which carbon dioxide is calcium salts. acid plaques in the blood vessels. transported in the blood. bony fishes Fishes with a bony rather than cartilaginous skeleton. atom Smallest particle of an element that displays the bilateral symmetry Body plan having two bottleneck effect Evolutionary event in which a properties of the element. corresponding or complementary halves. significant percentage of a population is prevented from reproducing, therefore reducing variation. atomic mass Average value of the mass numbers for all bile Secretion of the liver that is temporarily stored and Population bottlenecks increase the influence of isotopes of an element. concentrated in the gallbladder before being released genetic drift. into the small intestine, where it emulsifies fat. brain Primary organ of the central nervous system; site atomic number Number of protons within the nucleus of the majority of signal integration. of an atom. binary fission Splitting of a parent cell into two brain stem In mammals, portion of the brain that daughter cells; serves as an asexual form of consists of the medulla oblongata, pons, and midbrain atomic symbol One or two letters that represent the reproduction in bacteria. and connects the rest of the brain to the spinal cord. name of an element—e.g., H stands for a hydrogen bronchiole In terrestrial vertebrates, small tube that atom, and Na stands for a sodium atom. binge-eating disorder Condition characterized by conducts air from a bronchus to the alveoli. overeating episodes that are not followed by purging. bronchus (pl., bronchi) In terrestrial vertebrates, ATP synthase Enzyme that is part of an ATP synthase branch of the trachea that leads to one of the lungs. complex and functions in the production of ATP in binomial name Scientific name of an organism, the bryophytes Nonvascular plants—the mosses, chloroplasts and mitochondria. first part of which designates the genus and the liverworts, and hornworts. These plants have no second part of which designates the specific epithet. vascular tissue and occur in moist locations. atrioventricular valve Heart valve located between an buffer Substance or group of substances that tends to atrium and a ventricle. biodiversity Total number of different species living resist pH changes of a solution, thus stabilizing its on Earth. relative acidity and basicity. atrium (pl., atria) Chamber; particularly an upper bulimia nervosa Eating disorder characterized by binge chamber of the heart lying above a ventricle. biodiversity hotspots Regions on Earth that contain an eating followed by purging via self-induced vomiting above-average number of species; examples are coral or use of a laxative. australopithecine One of several species of reefs and rain forests. Australopithecus, a genus that contains the first generally recognized hominins. biogeochemical cycle Circulating pathway of an element, such as carbon or nitrogen, within an autoimmune disease Disease that results when the ecosystem, involving exchange pools, storage areas, immune system mistakenly attacks the body’s own and the biotic community. cells. biogeography Study of the geographical distribution of autonomic system Portion of the peripheral nervous life-forms on Earth. system that automatically and involuntarily regulates the activity of glands and cardiac and bioinformatics The application of computer technologies smooth muscle; divided into parasympathetic and to study the genome and other molecular data. sympathetic divisions. biological magnification Process by which substances autosome Any chromosome other than a sex (X or Y) become more concentrated in organisms in the chromosome. higher trophic levels of a food web. autotroph Organism that can capture energy and biological molecule Organic molecule found in cells: synthesize organic molecules from inorganic carbohydrate, lipid, protein, or nucleic acid. nutrients.
Glossary G-3 C cell cycle Repeating sequence of events in eukaryotes chemoheterotrophs Organisms that get their energy that involves cell growth and nuclear division; and nutrients from digesting organic materials from C3 photosynthesis Photosynthetic process where the consists of the stages G1, S, G2, and M. other organisms. first stable product of photosynthesis is a 3-carbon molecule. cell plate Structure across a dividing plant cell that chemoreceptors Receptors in the nervous system that signals the location of new plasma membranes and detect chemicals in the environment. C4 photosynthesis Photosynthetic process where the cell walls. plant fixes carbon dioxide to produce a C4 molecule chitin Strong but flexible nitrogenous polysaccharide that releases carbon dioxide to the Calvin cycle. cell signaling The process by which cells communicate found in the exoskeleton of arthropods. with other cells and detect changes in their calcitonin Hormone secreted by the thyroid gland that environment. chlamydia Bacterial STD of the lower reproductive helps regulate the blood calcium level. tract that can result in pelvic inflammatory disease. cell theory One of the major theories of biology which calorie Amount of heat energy required to raise the states that all organisms are made up of cells, cells chlorofluorocarbons (CFCs) Organic compounds temperature of 1 gram of water 1°C. are capable of self-reproduction, and cells come only containing carbon, chlorine, and fluorine atoms. from preexisting cells. CFCs, such as freon, can deplete the ozone shield by Calvin cycle Portion of photosynthesis that takes place releasing chlorine atoms in the upper atmosphere. in the stroma of chloroplasts and can occur in the cell wall Structure that surrounds a plant, protistan, dark. It uses the products of the light reactions to fungal, or bacterial cell and maintains the cell’s chlorophyll Green pigment that absorbs solar energy reduce CO2 to a carbohydrate. shape and rigidity. and is important in algal and plant photosynthesis; occurs as chlorophyll a and chlorophyll b. calyx The sepals, collectively; the outermost flower whorl. cellular respiration Metabolic reaction that uses CAM photosynthesis Form of photosynthesis that is the energy from the breakdown of carbohydrates chloroplast Membrane-bound organelle in algae and (primarily glucose), fatty acids, or amino acids to plants with chlorophyll-containing membranous based on crassulacean-acid metabolism. A plant produce ATP molecules. thylakoids; where photosynthesis takes place. fixes carbon dioxide at night to produce a C4 molecule that releases carbon dioxide to the Calvin cellulose Polysaccharide that is the major complex cholesterol One of the major lipids found in animal cycle during the day. carbohydrate in plant cell walls. plasma membranes; makes the membrane cancer Malignant tumor whose nondifferentiated impermeable to many molecules. cells exhibit loss of contact inhibition, uncontrolled central nervous system (CNS) Portion of the nervous growth, and the ability to invade tissue and system consisting of the brain and spinal cord. chordate Animal that has a dorsal tubular nerve cord, a metastasize. notochord, pharyngeal pouches, and a postanal tail at capillary Microscopic blood vessel. Gases and other centriole Cell organelle, existing in pairs, that is located some point in its life cycle. substances are exchanged across the walls of a in the centrosome and may help organize a mitotic capillary between blood and interstitial fluid. spindle for chromosome movement during animal chorionic villus sampling (CVS) Prenatal test in which capsid Protective protein container that surrounds the cell division. a sample of chorionic villi cells is removed for genetic material of a virus. diagnostic purposes. capsule Gelatinous layer surrounding the cells of green centromere Constricted region on a chromosome algae and certain bacteria. where two sister chromatids are joined. chromatid Single DNA strand of a chromosome. carbohydrate Class of organic compounds that Chromosomes may consist of a pair of sister includes monosaccharides, disaccharides, and centrosome Microtubule organizing center of cells. In chromatids. polysaccharides; present in food as sugars, starch, animal cells, it contains two centrioles. and fiber. chromatin Network of fibrils consisting of DNA and carcinogenesis Development of cancer. cephalization Having a well-recognized anterior head associated proteins observed within a nucleus that is cardiac cycle One complete cycle of systole and with a brain and sensory receptors. not dividing. diastole for all heart chambers. cardiac muscle Striated, involuntary muscle tissue cephalopod Type of mollusc in which a modified chromosome Structure, consisting of DNA complexed found only in the heart. foot develops into the head region; includes squids, with proteins, that transmits genetic information cardiovascular system Organ system in which blood octopuses, and nautiluses. from the previous generation of cells and organisms vessels distribute blood under the pumping action of to the next generation. the heart. cerebellum In terrestrial vertebrates, portion of the brain carnivore Consumer in a food chain that eats other that coordinates skeletal muscles to maintain posture chyme Thick, semiliquid food material that passes from animals. and balance and produce smooth, graceful motions. the stomach to the small intestine. carotenoid Yellow or orange pigment that serves as an accessory to chlorophyll in photosynthesis. cerebral cortex Outer layer of gray matter that cilium (pl., cilia) Short, hair-like projection from the carotid body Structure located at the branching of the covers the cerebrum; interprets sensation, initiates plasma membrane, occurring usually in large numbers. carotid arteries; contains chemoreceptors sensitive voluntary movement, and carries out higher thought to hydrogen ion and carbon dioxide concentrations processes. circulatory system Organ system of animals that is in blood. responsible for supplying oxygen and nutrients to the carpel Ovule-bearing unit that is a part of a pistil. cervical cap Birth control device made of latex in the cells of the organism and removing carbon dioxide carrying capacity Number of organisms of a particular shape of a cup, which covers the cervix; considered and waste materials. species that can be maintained indefinitely by a a mini-diaphragm. given environment. citric acid cycle Cycle of reactions in mitochondria cartilage Connective tissue in which the cells lie within cervix Narrow end of the uterus leading into the that begins with citric acid. It breaks down an acetyl lacunae separated by a flexible matrix. vagina. group and produces CO2, ATP, NADH, and FADH2; cartilaginous fishes Fishes with a cartilaginous also called the Krebs cycle. rather than bony skeleton; include sharks, rays, character displacement Tendency for characteristics and skates. to be more divergent when similar species belong clade A group of organisms that includes a common cell Fundamental unit of life. Lowest level of to the same community than when they are isolated ancestor and all of its descendants and that has its biological organization that has all of the from one another. own particular derived traits. characteristics of life. cell body Portion of a neuron that contains a nucleus charophytes A group of freshwater green algae thought cladistics School of systematics that uses traits derived and from which dendrites and an axon extend. to be the closest relatives of land plants. from a common ancestor to trace the evolutionary history of groups and construct cladograms. checkpoint In the cell cycle, one of several points where the cell cycle can stop or continue on, cladogram Branching diagrammatic tree used to depict depending on the influence of internal and external the evolutionary history of a group of organisms. signals; ensures that each step of the cell cycle is completed before the next one begins. class One of the categories, or taxa, used by taxonomists to group species; the taxon above the order level. chemoautotroph Organism able to synthesize organic molecules by using carbon dioxide as the carbon cleavage Cell division without cytoplasmic addition or source and the oxidation of an inorganic substance enlargement; occurs during the first stage of animal (such as hydrogen sulfide) as the energy source. development. chemoheterotroph Organism that is unable to climate change Overall change in global weather patterns reproduce its own organic molecules and therefore caused by any number of human-related events. requires organic nutrients in its diet. climax community In ecology, the community that results when succession has come to an end.
G-4 Glossary clonal selection model Mechanism of antibody response gametophyte) or seeds (female gametophyte). The cyanobacteria Photosynthetic bacteria that contain whereby an antigen selects which B lymphocyte sporangia-bearing structures of certain seedless chlorophyll and release O2; formerly called blue- will undergo clonal expansion and produce more vascular plants are also termed cones. green algae. lymphocytes bearing the same type of receptor. conifer Member of a group of cone-bearing gymnosperm plants, including pine, cedar, and cyclin Protein that cycles in quantity as the cell cycle clone An identical genetic copy of a cell or organism. spruce trees. progresses; combines with and activates the kinases closed circulatory system In all vertebrates and some conjugation Transfer of genetic material from one cell that promote the events of the cycle. to another. invertebrates, cardiovascular system composed of a connective tissue Type of animal tissue that binds cytokinesis Division of the cytoplasm following mitosis muscular heart and blood vessels. structures together, provides support and protection, and meiosis. clumped distribution Spatial distribution of fills spaces, stores fat, and forms blood cells. individuals in a population in which individuals are conservation biology Field of biology that focuses cytokinin Plant hormone that promotes cell division; more dense in one area than in another. on conserving natural resources and preserving often works in combination with auxin during organ cnidarian Invertebrate existing as either a polyp or a biodiversity. development in plant embryos. medusa with two tissue layers and radial symmetry. consumer Organism that feeds on another organism codominance Inheritance pattern in which both alleles in a food chain; primary consumers eat plants, and cytosine (C) One of four nitrogen-containing bases in of a gene are equally expressed in a heterozygote. secondary consumers eat animals. the nucleotides composing the structure of DNA and codon Three-base sequence in mRNA that causes the contraceptive implant Birth control method utilizing RNA; pairs with guanine. addition of a particular amino acid onto a protein or synthetic progesterone; prevents ovulation by the termination of translation. disrupting the ovarian cycle. cytoskeleton Internal framework of the cell, consisting coelom Body cavity, lying between the digestive contraceptive injection Birth control method utilizing of microtubules, actin filaments, and intermediate tract and body wall, that is completely lined by progesterone or estrogen and progesterone; prevents filaments. mesoderm. ovulation by disrupting the ovarian cycle. coelomates Animals that possess a true coelom as their contraceptive vaccine Under development, this birth cytotoxic T cell T cell that attacks and kills antigen- body cavity. control method immunizes against the hormone bearing cells. coenzyme Nonprotein organic molecule that aids the hCG, crucial to maintaining implantation of the action of an enzyme. embryo. D coevolution Joint evolution in which one species exerts control group Sample that goes through all the steps of selective pressure on another species. an experiment but is not exposed to the experimental data (sing., datum) Facts, or information, collected Cohesion Ability of water molecules to cling to each variable; a standard against which the results of an through observation and/or experimentation. other due to hydrogen bonding. experiment are checked. cohesion-tension model Explanation that says that convergent evolution Acquisition of the same or decomposer Organism, usually a bacterium or fungus, the upward transport of water in xylem is due to similar traits in distantly related lines of descent. that breaks down dead organic matter into inorganic transpiration-created tension and the cohesive copulation Sexual union between a male and a female. nutrients that can be recycled in the environment. properties of water molecules. corolla The petals, collectively; usually the collecting duct Duct in the kidneys that receives fluid conspicuously colored whorl of a flower. deforestation Removal of trees from a forest in a way from several nephrons. The reabsorption of water cortex In plant stems and roots, a band of ground tissue that reduces the extent of the forest. occurs here. made up of parenchyma cells and bounded by the commensalism Interaction in which one species epidermis and vascular tissue; in animals, outer layer dehydration synthesis reaction Chemical reaction is benefited and the other is neither harmed nor of an organ, such as the cortex of the kidneys or resulting in a covalent bond with the accompanying benefited. adrenal gland. loss of a water molecule. common ancestor Ancestor held in common by at least cotyledon Seed leaf of an embryo of a flowering plant; two lines of descent. provides nutrient molecules for the developing plant deletion Change in chromosome structure in which the community All the populations in a particular locale. before photosynthesis begins. end of a chromosome breaks off or two simultaneous compact bone The more dense form of bone; contains covalent bond Chemical bond in which atoms share breaks lead to the loss of an internal segment; often osteons containing concentric circles surrounding one or more pairs of electrons. causes abnormalities—e.g., cri du chat syndrome. bone cells called osteocytes. cranial nerve Nerve that arises from the brain. companion cell Type of cell found in the phloem of Cro-Magnons Common name for the oldest fossils to demographics Study of the characteristics of a plants that aids in the transport of nutrients. be designated Homo sapiens. population and the changes in those characteristics competition Interaction between two species in which crossing-over Exchange of genetic material between over time. both need the same limited resource, which results in nonsister chromatids of a tetrad during meiosis. harm to both. crustacean Member of a group of marine arthropods denatured Loss of an enzyme’s normal shape, so that competitive exclusion principle Theory that no two that contains, among others, shrimps, crabs, crayfish, it no longer functions; caused by a less than optimal species can occupy the same niche at the same time. and lobsters. pH and temperature. complement system Series of proteins in plasma that culture Total pattern of human behavior and products; provide a nonspecific defense mechanism against includes technology and the arts and is dependent on dendrite Part of a neuron that sends signals toward the invasion by pathogens; this mechanism complements the capacity to speak and transmit knowledge. cell body. certain immune responses. Cushing syndrome Condition resulting from complementary base pairing Hydrogen bonding hypersecretion of adrenal cortex hormones; Denisovans Recently discovered group of the genus between particular purines and pyrimidines in DNA. characterized by masculinization in women, a “moon Homo that existed in the region that is now Siberia compound Substance having two or more different face” in both men and women, and an increase in around 1 MYA. elements united chemically in a fixed ratio. blood glucose and sodium levels. conclusion Statement made following an experiment as cutaneous receptor Sensory receptor for pressure, density-dependent factor Biotic factor, such as to whether or not the results support the hypothesis. pain, touch, and temperature; found in the dermis of disease, competition, or predation, that affects condom Plastic contraceptive that prevents the the skin. population size according to the population’s density. fertilization of an egg by a sperm. May be worn by cuticle Waxy layer covering the epidermis of plants; male or female. protects the plant against water loss and disease- density-independent factor Abiotic factor, such as fire cone In vertebrate eyes, photoreceptor cell that responds causing organisms. or flood, that affects population size independent of to bright light and makes color vision possible. In the population’s density. conifers, structure that bears either pollen (male deoxyribose Pentose monosaccharide sugar that is found in DNA and has one less hydroxyl group than ribose. desertification Conversion of semiarid land to desertlike conditions, often beginning with overgrazing. detrital food web Complex pattern of interlocking and crisscrossing food chains that begins with a population of decomposers. detritus Organic matter produced by decomposition of substances, such as tissues and animal wastes. deuterostome Coelomate animals in which the second embryonic opening is associated with the mouth. The first embryonic opening, the blastopore, is associated with the anus.
Glossary G-5 development Events that occur from fertilization until DNA replication Synthesis of a new DNA double helix electron Negative subatomic particle moving about in the formation of an adult organism. prior to mitosis or meiosis in eukaryotic cells and an energy level around the nucleus of an atom. during prokaryotic fission in prokaryotic cells. diabetes mellitus Condition characterized by a high electron shell Average location, or energy level, of blood glucose level and the appearance of glucose in domain Largest of the categories, or taxa, used by an electron in an atom. Often shown as concentric the urine, due to a deficiency of insulin production taxonomists to group species. The three domains are circles around the nucleus of an atom. Also called and failure of cells to take up glucose. Archaea, Bacteria, and Eukarya. orbitals. dialysis Movement of dissolved molecules through a domain Archaea One of the three domains of life; electron transport chain Passage of electrons along semipermeable membrane by diffusion. Used to contains prokaryotic cells that often live in extreme a series of electron carriers from a higher to remove compounds from blood in kidney patients. habitats and have unique genetic, biochemical, lower energy levels; the energy released is used to and physiological characteristics; its members are synthesize ATP. diaphragm In mammals, a muscular, membranous sometimes referred to as archaea. partition separating the thoracic cavity from the electronegativity Ability of an atom to attract electrons abdominal cavity; important in inhalation. Also, a domain Bacteria One of the three domains of life; toward itself in a chemical bond. birth control device consisting of a soft, latex cup contains prokaryotic cells that differ from archaea that fits over the cervix. because they have unique genetic, biochemical, and element Substance that cannot be broken down into physiological characteristics. substances with different properties; composed of diarrhea Excessively frequent and watery bowel only one type of atom. movements. domain Eukarya One of the three domains of life, consisting of organisms with eukaryotic cells and embryo sac Female gametophyte of flowering plants. diastole Relaxation period of a heart chamber during further classified into the kingdoms Protista, Fungi, embryonic development Period of animal development the cardiac cycle. Plantae, and Animalia. that encompasses all of the events from fertilization diet A person’s typical food choices. A balanced diet dominant allele Allele that exerts its phenotypic effect until the full formation of a new individual. contains all the nutrients in the right proportions to in the heterozygote. It masks the expression of the embryonic stem cell Undifferentiated cell, obtained maintain a healthy body. recessive allele. from an embryo, that can be manipulated to become a specialized cell type, such as a muscle, nerve, or dietary supplement Nutrient or plant product (e.g., double fertilization In flowering plants, event in which red blood cell. herbal tea, protein supplement) used to enhance one sperm nucleus unites with the egg nucleus and emergency contraception Forms of contraception that health. Supplements do not undergo the same safety the other sperm nucleus unites with the polar nuclei are used after intercourse to stop a pregnancy. and effectiveness testing required for prescription of an embryo sac. emerging disease Infectious disease that has not drugs. previously been detected in humans. Down syndrome Trisomy 21. The individual has emerging virus Causative agent of a disease that is diffusion Passive movement of molecules or ions from three copies of chromosome 21 and the following new or is demonstrating increased prevalence, such an area of higher concentration to an area of lower characteristics: mental disabilities of varying degree, as the viruses that cause AIDS, SARS, and avian concentration. short stature, an eyelid fold, stubby fingers, and a influenza. palm crease. emulsification Breaking up of fat globules into smaller digestive system Organ system that includes the droplets by the action of bile salts or any other mouth, esophagus, stomach, small intestine, and duplication Change in chromosome structure in which emulsifier. large intestine (colon). It receives and digests food a particular segment is present more than once in the endemic goiter Condition in which an enlarged thyroid into nutrient molecules and has associated organs: same chromosome. produces low levels of thyroxine. teeth, tongue, salivary glands, liver, gallbladder, and endocrine gland Ductless organ that secretes one or pancreas. dyad Chromosome composed of two sister more hormones into the blood. chromatids. endocrine system Organ system that consists of dihybrid cross Genetic cross involving two traits, where hormonal glands and is involved in the coordination the individuals involved in the cross are heterozygous E of body activities; secretes hormones as chemical for both traits; example is AaBb × AaBb messengers. echinoderm Marine invertebrate, such as a sea star, endocytosis Process by which substances are moved diploid (2n) number Cell condition in which two of sea urchin, or sand dollar; characterized by radial into the cell from the environment by phagocytosis each type of chromosome are present. symmetry and a water vascular system. (cellular eating) or pinocytosis (cellular drinking); includes receptor-mediated endocytosis. directional selection Outcome of natural selection ecological niche Role an organism plays in its endoderm Innermost primary germ layer of an animal in which an extreme phenotype at one end of a community, including its habitat and its interactions embryo that gives rise to the linings of the digestive population distribution is favored over all other with other organisms. and respiratory tracts and their associated structures. phenotypes, leading to one distinct form. endodermis Internal tissue of a plant root forming ecological pyramid A diagram that depicts the transfer a boundary between the cortex and the vascular disaccharide Sugar that contains two units of a of nutrients and energy among various trophic levels cylinder. monosaccharide. One example is maltose. in a food chain or web. endomembrane system Collection of membranous structures involved in transport within the cell. disruptive selection Outcome of natural selection in ecological succession Gradual replacement of endoplasmic reticulum (ER) System of membranous which both extreme phenotypes at the ends of a communities in an area following a disturbance channels and saccules in the cytoplasm, often with population distribution are favored over the average (secondary succession) or the creation of new soil attached ribosomes. phenotype, leading to more than one distinct form. (primary succession). endoskeleton Protective internal skeleton, as in vertebrates. distal convoluted tubule Final portion of a nephron ecology Scientific study of the interactions of endosperm In flowering plants, nutritive storage tissue that joins with a collecting duct; associated with organisms with each other and with their physical derived from the union of a sperm nucleus and polar tubular secretion. environment. nuclei in the embryo sac. endospore Spore formed by certain types of bacteria in diversity Measure of both species richness and species ecosystem A community of living organisms along response to unfavorable environmental conditions. distribution in a community. with their physical environment; characterized by endosymbiotic theory Explanation for the evolution of a flow of energy and a cycling of inorganic nutrients. eukaryotic organelles that involves the establishment DNA (deoxyribonucleic acid) Nucleic acid polymer of symbiotic relationships between bacteria to form produced from covalent bonding of nucleotide ectoderm Outermost primary germ layer of an animal the internal organelles of eukaryotic cells. monomers that contain the sugar deoxyribose; the embryo; gives rise to the nervous system and the genetic material of nearly all organisms. outer layer of the integument. DNA fingerprinting Use of DNA fragment lengths ectothermic Having a body temperature that varies resulting from restriction enzyme cleavage to according to the environmental temperature. identify individuals. edema Swelling due to fluid accumulation in the DNA ligase Enzyme that links DNA fragments; used intercellular spaces in tissues. during production of recombinant DNA to join foreign DNA to vector DNA. electrocardiogram (ECG) Recording of the electrical activity associated with the heartbeat. DNA polymerase During replication, the enzyme that joins the nucleotides so that their sequence is complementary to that in the parental strand.
G-6 Glossary endothermic Maintaining a constant body temperature exocrine gland Gland that discharges its secretion into flatworm Invertebrate, such as a planarian or by generating internal heat. one or more ducts. The pancreas is an exocrine gland tapeworm, that has a thin body, three-branched when it secretes pancreatic juice into the duodenum. gastrovascular cavity, bilateral symmetry, and energy Capacity to do work and bring about change; ladderlike nervous system; member of phylum occurs in a variety of forms. exocytosis Process in which an intracellular vesicle Platyhelminthes. fuses with the plasma membrane, so that the energy of activation (Ea) Energy that must be added in vesicle’s contents are released outside the cell. flower Reproductive organ of a flowering plant (an order for molecules to react with one another. angiosperm), consisting of several kinds of modified exoskeleton Protective external skeleton, as in leaves arranged in concentric rings and attached to a enhancer Region of DNA that stimulates transcription arthropods. modified stem called a receptacle. of nearby genes; functions by acting as a binding site for transcription factors. exotic species Species that is new to a community follicle In the ovary of an animal, structure that contains (nonnative). an oocyte; site of oocyte production. entropy Measure of disorder, randomness or disorganization of a system. experiment Series of actions undertaken to collect data follicular phase First half of the ovarian cycle, during with which to test a hypothesis. which the follicle matures and much estrogen (and enzyme Organic catalyst, usually a protein, that speeds some progesterone) is produced. a reaction in cells due to its shape. experimental design Artificial situation devised to test a hypothesis. food chain Order in which one population feeds on epidermal tissue (epidermis) Tissue that forms the another in an ecosystem, thereby showing the flow outer protective layer on a part of a plant. experimental variable In a scientific experiment, of energy from a decomposer (detrital food chain) a condition of the experiment that is deliberately or a producer (grazing food chain) to the final epigenetic inheritance Transmission of genetic changed. consumer. information by means that are not based on the coding sequences of a gene. expiration Movement of air out of the lungs by positive food web In an ecosystem, a complex pattern of linked pressure. and crisscrossing food chains, showing the energy epiglottis Structure that covers the glottis and closes off flow between the components of the ecosystem. the air tract during the process of swallowing. exponential growth Growth, particularly of a population, in which the increase occurs in the same formed elements Constituents of blood that are either epistatic interaction Pattern of inheritance where one manner as compound interest. cellular (red blood cells and white blood cells) or at gene overrides or cancels the instructions of another least cellular in origin (platelets). gene. extinction Total disappearance of a species or higher group. fossil Remains of a once-living organism that have been epithelial tissue Tissue that forms external coverings preserved in the Earth’s crust. and internal linings of many organs and covers the extracellular matrix (ECM) Meshwork of entire surface of the body; also called epithelium. polysaccharides and proteins that provides support fossil fuel Fuel such as oil, coal, and natural gas that for an animal cell and affects its behavior. is the result of partial decomposition of plants and equilibrium species Species demonstrating a life animals coupled with exposure to heat and pressure history pattern in which members exhibit logistic F for millions of years. population growth and the population size remains at or near the carrying capacity. Its members are family One of the categories, or taxa, used by fossil record History of life recorded in remains from large and slow to mature, have a long life span and taxonomists to group species; the taxon above the the past that are found in rock strata. few offspring, and provide much care to offspring genus level. (e.g., bears, lions). founder effect Mechanism of genetic drift that occurs fat Organic molecule that contains glycerol and fatty when a new population is established by a small esophagus Muscular tube for moving swallowed food acids and is found in adipose tissue of vertebrates. number of individuals, carrying only a small fraction from the pharynx to the stomach. of the original population’s genetic variation. The fatty acid Molecule that contains a hydrocarbon chain alleles carried by these individuals often, by chance, essential nutrient Substance that contributes to good that ends with a carboxyl group. do not occur in the same frequency as in the original health and must be supplied by the diet because population. the body either cannot synthesize it or makes an feedback inhibition Mechanism for regulating insufficient amount. metabolic pathways in which the concentration frameshift mutation Alteration in a DNA sequence of the product is kept within a certain range until due to addition or deletion of a nucleotide, so the estrogen Female sex hormone that helps maintain binding of the substrate to the enzyme’s active site reading “frame” is shifted; this type of mutation can sexual organs and secondary sex characteristics. reduces (or stops) the activity of the pathway. result in a nonfunctional protein. ethylene Plant hormone that causes ripening of fruit fermentation Anaerobic breakdown of glucose that fruit In flowering plants, the structure that forms from and is involved in abscission. results in a gain of 2 ATP and end products, such as an ovary and associated tissues and encloses seeds. alcohol and lactate. euchromatin Chromatin that is extended and accessible functional group Specific cluster of atoms attached to for transcription. fern Member of a group of plants that have large the carbon skeleton of organic molecules that enters fronds. In the sexual life cycle, the independent into reactions and behaves in a predictable way. eudicot Eudicotyledon; member of a flowering gametophyte produces flagellated sperm, and the plant group that has two embryonic leaves vascular sporophyte produces windblown spores. fungus (pl., fungi) Saprotrophic decomposer. The body is (cotyledons), net-veined leaves, vascular bundles made up of filaments, called hyphae, that form a mass in a ring, and flower parts in fours or fives and fertilization Fusion of sperm and egg nuclei, producing called a mycelium. Member of the kingdom Fungi. their multiples. a zygote that develops into a new individual. G eukaryotic cell Type of cell that has a membrane- fiber Structure resembling a thread; also carbohydrate bound nucleus and membranous organelles; found in plant material that is nondigestible. gallbladder Organ connected to the liver that stores and organisms within the domain Eukarya. concentrates bile. filament End-to-end chain of cells that forms as cell eutrophication Overenrichment of a body of water division occurs in only one plane; in plants, the gamete Haploid sex cell: egg or sperm. with inorganic nutrients used by phytoplankton. elongated stalk of a stamen. gametophyte Haploid generation of the life cycle of a Often, overenrichment caused by human activities leads to excessive bacterial growth and oxygen filtration Movement of small molecules from a blood plant; produces gametes that unite to form a diploid depletion. capillary into the glomerular capsule of a nephron zygote. due to the action of blood pressure. ganglion Collection of neuron cell bodies found within evolution Inheritable changes in a population over the peripheral nervous system. time that make the population better adapted to their fitness The reproductive success of an individual gap junction Junction between cells formed by environment. relative to other members of a population. the joining of two adjacent plasma membranes; lends strength and allows ions, sugars, and small evolutionary tree Diagram that shows the evolutionary five-kingdom system System of classification that molecules to pass between cells. history of groups of organisms. contains the kingdoms Monera, Protista, Plantae, Animalia, and Fungi. ex vivo gene therapy Gene therapy in which infected tissue is removed from an organism, injected with flagellum (pl., flagella) Long, slender extension used normal genes, and then returned to the organism. for locomotion by some bacteria, protozoans, and The normal genes divide, producing normal genes sperm. and tissues instead of infected ones.
Glossary G-7 gastropod Mollusc with a broad, flat foot for crawling glycerol Three-carbon carbohydrate with three hydroxyl helper T cell Cell that secretes cytokines, which (e.g., snails and slugs). groups attached; a component of fats and oils. stimulate all kinds of immune cells. gastrulation Formation of a gastrula from a blastula; glycogen Storage polysaccharide found in animals; heme Iron-containing group found in hemoglobin. characterized by an invagination of the cell layers to composed of glucose molecules joined in a linear hemocoel Body cavity in arthropods where exchange form a caplike structure. fashion but having numerous branches. between hemolymph and tissues occurs. gene Unit of heredity existing as alleles on the glycolysis Anaerobic breakdown of glucose that results hemoglobin Iron-containing respiratory pigment chromosomes. In diploid organisms, typically two in a gain of 2 ATP and the end product pyruvate. alleles are inherited—one from each parent. occurring in vertebrate red blood cells and in the Golgi apparatus Organelle, consisting of saccules and blood plasma of some invertebrates. gene flow Movement of alleles among populations by vesicles, that processes, packages, and distributes hepatitis Viral infection of the liver; can be transmitted migration of breeding individuals. molecules about or from the cell. sexually and can lead to liver failure and liver cancer. herbivore Primary consumer in a grazing food chain; gene pool The various alleles at all the gene loci in all Golgi tendon Proprioceptive sensory receptor located plant eater. individuals in a population. where skeletal muscle inserts into tendons; sensitive hermaphrodite An animal that has both male and to changes in tendon tension. female sex organs. gene therapy Insertion of genetic material into human heterochromatin Highly compacted chromatin that is cells for the treatment of a disorder. gonads Organs that produce gametes. The ovary not accessible for transcription. produces eggs, and the testis produces sperm. heterotroph Organism that cannot synthesize organic genetic counseling Consultation between prospective compounds from inorganic substances and therefore parents and a counselor who determines the gonorrhea Bacterial STD that can lead to sterility or must take in organic nutrients. genotype of each and whether an unborn child will infertility. heterozygous Possessing unlike alleles for a particular have an inherited disorder. trait. gravitational equilibrium Maintenance of balance hinge joint Synovial joint (at elbow or knee) that genetic drift Mechanism of evolution due to random that depends on sensing the position of the head in permits movement in one direction only. changes in the allele frequencies of a gene pool; relation to gravity; involves the utricle and saccule of histamine Substance, produced by basophils in blood more likely to occur in small populations or the inner ear. and mast cells in connective tissue, that causes when only a few individuals of a large population capillaries to dilate. reproduce. gravitropism Growth response of plant roots and histone Protein molecule responsible for packing stems to Earth’s gravity. Roots demonstrate positive chromatin. genetic engineering Alteration of genomes for medical gravitropism, and stems demonstrate negative homeostasis Maintenance of the relatively constant or industrial purposes. gravitropism. condition of the internal environment of the body within an acceptable range. genetic marker Abnormality in the sequence of bases grazing food web Complex pattern of linked and hominid Family designation for humans, apes (African at a particular location on a chromosome, signifying crisscrossing food chains that begins with a and Asian), and chimpanzees. a disorder. population of photosynthesizers serving as hominin Designation that includes humans and extinct producers. species very closely related to humans. genetically modified organism (GMO) An organism Homo erectus Early species of the genus Homo that whose genetic material has been changed, usually greenhouse effect Reradiation of solar heat toward used fire and migrated out of Africa to Europe and by using genetic engineering techniques such as the Earth, caused by gases such as carbon dioxide, Asia. recombinant DNA technology. methane, nitrous oxide, water vapor, and nitrous Homo habilis Early species of the genus Homo, dated oxide in the atmosphere. between 2.4 and 1.4 MYA and believed to have been genital herpes Viral STD characterized by painful the first tool users. blisters on the genitals. ground tissue Tissue that constitutes most of the body homologous chromosome Homologue; member of of a plant; consists of parenchyma, collenchyma, and a pair of chromosomes that are alike and come genome Sum of all of the genetic material in a cell or sclerenchyma cells that function in storage, basic together in synapsis during prophase of the first organism. metabolism, and support. meiotic division. homologous structure In evolution, a structure that genome editing Form of DNA technology that uses growth factor Chemical signal that regulates mitosis is similar in different types of organisms because nucleases that can target specific sequences of and differentiation of cells that have receptors for it; these organisms are descended from a common nucleotides in the genome of an organism for important in such processes as fetal development, ancestor. inactivation or insertion of new nucleotides. tissue maintenance and repair, and hematopoiesis; homologue Homologous chromosome; member of sometimes a contributing factor in cancer. a pair of chromosomes that are alike and come genomics Study of genomes. together in synapsis during prophase of the first genotype Combination of alleles that determines a guanine (G) One of four nitrogen-containing bases in meiotic division. nucleotides composing the structure of DNA and homozygous Possessing two identical alleles for a particular trait in an organism; often designated by RNA; pairs with cytosine. particular trait. letters—for example, BB or Aa. hormone Chemical messenger produced by a gland that genus One of the categories, or taxa, used by gymnosperm Type of woody seed plant in which the controls the activity of other tissues, organs, or cells taxonomists to group species; contains those species seeds are not enclosed by fruit and are usually borne of the body. that are most closely related through evolution. in cones, such as those of the conifers. human immunodeficiency virus (HIV) Virus germ layer One of the primary tissue layer of a responsible for AIDS. vertebrate embryo—namely, the ectoderm, H human papillomavirus (HPV) Virus that is mesoderm, or endoderm. responsible for genital warts and cervical cancer. germinate Beginning of growth of a seed, spore, or habitat Place where an organism lives and is able to hydrogen bond Weak chemical bond between a slightly zygote, especially after a period of dormancy. survive and reproduce. positive hydrogen atom on one molecule and a gibberellin Plant hormone promoting increased slightly negative atom on another molecule. stem growth; also involved in flowering and seed halophile Type of archaea that lives in extremely salty hydrolysis reaction Splitting of a compound by the germination. habitats. addition of water, with the H+ being incorporated gland Group of epithelial cells that are specialized to into one molecule and the OH¯ into the other. produce a substance. haploid (n) number Cell condition in which only one global warming Predicted increase in the Earth’s of each type of chromosome is present. temperature due to human activities that promote the greenhouse effect. heart Muscular organ whose contraction causes blood glomerular capsule Cuplike structure that is the initial or other fluid to circulate in the body of an animal. portion of the nephron. glottis Opening for airflow in the larynx. heart attack Myocardial infarction; damage to the glucagon Hormone, secreted by the pancreas, that myocardium due to blocked circulation in the causes the liver to break down glycogen and raises coronary arteries. the blood glucose level. glucose Six-carbon sugar that organisms break down as heat Type of kinetic energy. Captured solar energy a source of energy during cellular respiration. eventually dissipates as heat in the environment. helicase The enzyme in DNA replication that separates DNA strands by breaking the hydrogen bonds between the strands.
G-8 Glossary hydrophilic Type of molecule that interacts with water integration Summing up of excitatory and inhibitory L by dissolving in it and/or by forming hydrogen bonds signals by a neuron or a part of the brain. with water molecules. lacteal Lymphatic capillary in an intestinal villus; aids integumentary system Organ system consisting of the in the absorption of fats. hydrophobic Type of molecule that does not interact skin and its accessory structures. with water because it is nonpolar. lancelet Invertebrate chordate with a body that intergenic DNA The sequences of nucleotides that lie resembles a lancet and has the four chordate hydrostatic skeleton Fluid-filled body compartment between genes on a chromosome. characteristics as an adult. that provides support for muscle contraction resulting in movement; seen in cnidarians, interkinesis Period of time between meiosis I and large intestine In vertebrates, portion of the digestive flatworms, roundworms, and segmented worms. meiosis II during which no DNA replication takes tract that follows the small intestine; in humans, place. consists of the cecum, colon, rectum, and anal canal. hypertension Elevated blood pressure, particularly the diastolic pressure. interneuron In the central nervous system, a neuron larynx Voice box; cartilaginous structure located that conveys messages between parts of the central between the pharynx and the trachea; in humans, hypertonic solution Solution with a higher solute nervous system. contains the vocal cords. concentration (less water) than the cytoplasm of a cell; causes cells to lose water by osmosis. interphase Stages of the cell cycle (G1, S, G2) during law Universial principle that describes the basic which growth and DNA synthesis occur when the functions of the natural world. hyphae (sing., hypha) Filaments of the vegetative body nucleus is not actively dividing. of a fungus. law of independent assortment Alleles of unlinked intrauterine device (IUD) Birth control device genes assort independently of each other during hypothalamus In vertebrates, part of the brain that consisting of a small piece of molded plastic meiosis, so that the gametes contain all possible helps regulate the internal environment of the inserted into the uterus; believed to alter the combinations of alleles. body—for example, heart rate, body temperature, uterine environment, so that fertilization does and water balance. not occur. law of segregation Separation of alleles from each other during meiosis, so that the gametes contain hypothesis Supposition established by reasoning after inversion Change in chromosome structure in which one from each pair. Each resulting gamete has an consideration of available evidence. It can be tested a segment of a chromosome is turned 180°. The equal chance of receiving either allele. by obtaining more data, often by experimentation. reversed sequence of genes can lead to altered gene activity and abnormalities. leaf Lateral appendage of a stem, highly variable hypotonic solution Solution having a lower solute in structure, often containing cells that carry out (more water) concentration than the cytoplasm of a invertebrates Animals lacking an internal skeleton photosynthesis. cell; causes cells to gain water by osmosis. made of cartilage or bone. less-developed country (LDC) Country that is I ion Charged particle that carries a negative or positive becoming industrialized, with rapid population charge. growth and the majority of people living in poverty. immune system Cells and organs that protect the body against foreign organisms and substances as well as ionic bond Chemical bond in which ions are attracted lichen Symbiotic (mutualistic) relationship between cancerous cells. to one another by opposite charges. certain fungi and cyanobacteria or green algae, in which the fungi provide minerals and water and the immunity Ability of the body to protect itself from isomer Molecule with the same molecular formula as cyanobacteria or algae provide organic molecules, foreign substances and cells, including disease- another but having a different structure and therefore such as sucrose. causing agents. a different shape. life cycle Recurring pattern of genetically programmed in vivo gene therapy Gene therapy in which normal isotonic solution Solution that is equal in solute events by which individuals grow, develop, maintain genes are delivered directly into an organism. concentration to that of the cytoplasm of a cell; themselves, and reproduce. causes a cell to neither lose nor gain water by incomplete dominance Inheritance pattern in which osmosis. life history A particular mix of characteristics of a the offspring has an intermediate phenotype, as population or species, such as how many offspring it when a red-flowered plant and a white-flowered isotope Atom of the same element having the same produces, its survivorship, and factors (such as age plant produce pink-flowered offspring. atomic number but a different mass number due to and size) that determine its reproductive maturity. the number of neutrons. induced fit model Change in the shape of an enzyme’s ligament Tough cord or band of dense fibrous tissue active site that enhances the fit between the active J that binds bone to bone at a joint. site and its substrate(s). jawless fishes Group of fishes that have no jaws; light reactions Portion of photosynthesis that captures induction Ability of a tissue or organ to influence the includes hagfishes and lampreys. solar energy and takes place in thylakoid membranes development of another tissue or organ. of chloroplasts; produces ATP and NADPH. K inductive reasoning Using specific observations and limbic system In humans, complex network that the process of logic and reasoning to arrive at a karyotype Image of chromosomes arranged by pairs includes the diencephalon and areas of the cerebrum, hypothesis. according to their size, shape, and banding pattern. including the amygdala and hippocampus; governs learning and memory and various emotions, such as infertility The failure of a couple to achieve pregnancy keystone species Species whose activities significantly pleasure, fear, and happiness. after 1 year of regular, unprotected intercourse. affect community structure. lineage Evolutionary line of descent. inflammatory response Tissue response to injury kidneys Paired organs of the vertebrate urinary system linkage group Genes on the same chromosome that or pathogen that is characterized by redness, heat, that regulate the chemical composition of the blood swelling, and pain. and produce the waste product urine. tend to be inherited together. lipase Enzyme secreted by the pancreas that breaks innate immunity A function of the immune system that kilocalorie Measure of the caloric value of food; equal protects the body against pathogens in a nonspecific to 1,000 calories. down fats to glycerol and fatty acids. manner. lipid Class of organic compounds that tends to be kinase Enzyme that activates another enzyme by insect Type of arthropod. The head has antennae, adding a phosphate group. soluble in nonpolar solvents; includes fats and oils. compound eyes, and simple eyes; the thorax has liver Large, dark red internal organ that produces urea three pairs of legs and often wings; and the abdomen kinetic energy Energy associated with motion. has internal organs. kingdom One of the categories, or taxa, used by and bile, detoxifies the blood, stores glycogen, and produces the plasma proteins, among other inspiration Movement of air into the lungs by negative taxonomists to group species; the taxon above functions. pressure. phylum. lobe-finned fishes Bony fishes with limblike fins. Klinefelter syndrome Condition caused by the locus Specific location of a particular gene on insulin Hormone, secreted by the pancreas, that lowers inheritance of XXY chromosomes. homologous chromosomes. blood glucose level by promoting the uptake of logistic growth Population increase that results in an glucose by cells and the conversion of glucose to S-shaped curve. Growth is slow at first, steepens, glycogen by the liver and skeletal muscles. and then levels off due to environmental resistance.
Glossary G-9 lung Internal respiratory organ containing moist mast cell Type of white blood cell that releases midbrain Part of the brain stem located between the surfaces for gas exchange. histamine in the inflammatory response. diencephalon and the pons; contains visual and auditory reflex centers. luteal phase Second half of the ovarian cycle, during matrix Noncellular material that fills the spaces which the corpus luteum develops and much between cells in connective tissues and inside mineral An element that is needed in the diet for progesterone (and some estrogen) is produced. organelles. numerous physiological functions; a nonrenewable raw material in the Earth’s crust that can be mined lycophytes Club mosses; seedless plants with matter Anything that takes up space and has mass. and used by humans. microphylls and well-developed vascular tissue in mechanoreceptor Type of receptor that detects roots, stems, and leaves. mitochondrion (pl., mitochondria) Membrane- mechanical changes (such as movement). bounded organelle in which ATP molecules are lymph Fluid, derived from interstitial fluid, that is medulla oblongata In vertebrates, part of the brain produced during the process of cellular respiration. carried in lymphatic vessels. stem that is continuous with the spinal cord; controls mitosis Process in which a parent nucleus produces two lymph node Small mass of lymphatic tissue located heartbeat, blood pressure, breathing, and other vital daughter nuclei, each having the same number and along a lymphatic vessel; function is to filter excess functions. kinds of chromosomes as the parent nucleus. interstitial fluid (lymph) before it is returned to the megaphylls Large leaves with complex networks of circulatory system. veins. model system Simulation of a process; aids conceptual meiosis, meiosis I, meiosis II Type of nuclear division understanding until the process can be studied lymphatic system Organ system consisting of that occurs as part of sexual reproduction in which firsthand; a hypothesis that describes how a lymphatic vessels, lymph nodes, and other lymphatic the daughter cells receive the haploid number of particular process might be carried out. organs; absorbs fat from the digestive system, chromosomes in varied combinations. collects excess interstitial fluid (lymph), and aids the memory Capacity of the brain to store and retrieve molecule Union of two or more atoms of the same immune system. information about past sensations, perceptions, and element; also, the smallest part of a compound that events; essential to learning. retains the properties of the compound. lymphocyte Specialized white blood cell that functions Memory B cells B cells that are not used in the initial in specific defense and occurs in two forms: T cells adaptive response but are held in reserve to provide molluscs Animals characterized by a coelom, a and B cells. long-term immunity to an antigen. complete digestive tract, a muscular foot, and a menopause Termination of the ovarian and menstrual mantle; member of phylum Mollusca. lysogenic cycle Bacteriophage life cycle in which the cycles in older women. virus incorporates its DNA into that of a bacterium; menses Flow of blood during menstruation. monocot Monocotyledon; member of a flowering plant occurs preliminary to the lytic cycle. menstrual cycle Cycle that runs concurrently with the group that has one embryonic leaf (cotyledon), ovarian cycle. It prepares the uterus to receive a parallel-veined leaves, scattered vascular bundles, lysosome Membrane-bounded vesicle that contains developing zygote. and flower parts in threes or multiples of three. hydrolytic enzymes for digesting macromolecules. menstruation Periodic shedding of tissue and blood from the inner lining of the uterus in primates. monocyte Type of agranular leukocyte that functions as a lytic cycle Bacteriophage life cycle in which a virus meristem tissue Undifferentiated embryonic tissue in phagocyte, particularly after it becomes a macrophage. takes over the operation of a bacterium immediately the active growth regions of plants. upon entering it and subsequently destroys the mesoderm Middle primary germ layer of an animal monohybrid cross Cross that involves individuals bacterium. embryo that gives rise to several internal organ possessing two different alleles for a single trait; for systems and the dermis. example, Aa. M mesophyll Plant tissue where the majority of photosynthesis occurs. monomer Small molecule that is a subunit of a macroevolution Large-scale evolutionary change, such messenger RNA (mRNA) Type of RNA formed from polymer—e.g., glucose is a monomer of starch. as the formation of new species. a DNA template and bearing coded information for the amino acid sequence of a polypeptide. monosaccharide Simple sugar; a carbohydrate that macronutrient Essential element or other substance metabolism All of the chemical reactions that occur in cannot be broken down by hydrolysis—e.g., glucose. needed in large amounts by plants or humans. In a cell during growth and repair. plants, nitrogen, calcium, and sulfur are needed for metaphase Mitotic phase during which chromosomes monotreme Egg-laying mammal—for example, plant growth; in humans, carbohydrates, lipids, and are aligned at the spindle equator. duckbill platypus or spiny anteater. proteins supply the body’s energy needs. metastasis Spread of cancer from the place of origin throughout the body; caused by the ability of cancer more-developed country (MDC) Country that is macrophage In vertebrates, large, phagocytic cell cells to migrate and invade tissues. industrialized, with modest population growth and a derived from a monocyte that ingests microbes and methanogen Type of archaea that lives in oxygen-free fairly good standard of living. debris. habitats, such as swamps, and releases methane gas. microevolution Small, measurable evolutionary morula Spherical mass of cells resulting from cleavage major histocompatability complex (MHC) Cell changes in a population from generation to during animal development prior to the blastula surface proteins that recognize self cells and bind generation; change in allele frequencies within a stage. antigens for presentation to a T cell. population over time. micronutrient Essential element or other substance motor neuron Nerve cell that conducts nerve impulses major mineral Essential inorganic nutrient (such as needed in small amounts by plants or humans. In away from the central nervous system and innervates calcium, potassium, phosphorus, sodium, chloride, plants, boron, copper, and zinc are needed for plant effectors (muscle and glands). magnesium, or sulfur) required daily by humans to growth; in humans, vitamins and minerals help regulate metabolic activities and maintain health. regulate metabolism and physiological development. mouth In humans, organ of the digestive tract where microphylls Small, narrow leaves with single, food is chewed and mixed with saliva. malignant tumor Form of invasive tumor that may unbranched veins. spread to other tissues of the body. microtubule Small, cylindrical organelle composed of mRNA transcript Complementary copy of the tubulin protein around an empty central core; present sequence of bases in the template strand of DNA. Malpighian tubule Blind, threadlike excretory tubule in the cytoplasm, centrioles, cilia, and flagella. near the anterior end of an insect’s hindgut. microvillus (pl., microvilli) Cylindrical process that multicellular Organism composed of many cells; usually extends from an epithelial cell of a villus; increases has organized tissues, organs, and organ systems. mammal Endothermic vertebrate characterized the surface area of the cell. especially by the presence of hair and mammary multifactorial trait Trait controlled by multiple genes glands. subject to environmental influences. Each dominant allele contributes to the phenotype in an additive and marsupial Member of a group of mammals bearing like manner. immature young nursed in a marsupium, or pouch— for example, kangaroo or opossum. multipotent A term used to describe a stem cell that has the potential to form a limited number of cell types. mass extinction Episode of large-scale extinction in which large numbers of species disappear within a muscle dysmorphia Mental state in which a person relatively short period of time. thinks his or her body is underdeveloped and becomes preoccupied with body-building activities mass number Mass of an atom equal to the number and diet; affects more men than women. of protons plus the number of neutrons within the nucleus. muscular system Organ system consisting of muscles that produce movement, both movement in the body and movement of its limbs. The principal components are skeletal muscle, smooth muscle, and cardiac muscle.
G-10 Glossary muscular tissue Type of animal tissue composed body parts and the body’s responses to the external O of fibers that shorten and lengthen to produce and internal environments. movements. neuroglia Nonconducting cells in nervous tissue that obesity Excess adipose tissue; exceeding desirable support and nourish neurons. weight by more than 20%. mutagen Agent, such as radiation or a chemical, that neuron Nerve cell, which characteristically has three brings about a mutation in DNA. parts: dendrites, a cell body, and an axon. observation Step in the scientific method by which neurotransmitter Chemical stored at the ends of data are collected before a conclusion is drawn. mutation Change made in the nucleotide sequence axons; responsible for transmission of a nerve of DNA. Such changes may be due to a replication impulse across a synapse. octet rule States that an atom other than hydrogen tends error or the influence of external sources called neurulation Development of the central nervous to form bonds until it has eight electrons in its outer mutagens. Mutations generate variation in the gene system organs in an embryo. shell. An atom that already has eight electrons in its pool of a population. neutron Neutral subatomic particle, located in the outer shell does not react and is inert. nucleus and assigned one atomic mass unit. mutualism Interaction in which both species benefit in neutrophil Phagocytic, granular leukocyte that is the oil Triglyceride, usually of plant origin, that is terms of growth and reproduction. most abundant of the white blood cells; first to composed of glycerol and three fatty acids and respond to infection. is liquid in consistency due to many unsaturated mycelium Tangled mass of hyphal filaments composing nociceptor Type of pain receptor that is sensitive to bonds in the hydrocarbon chains of the fatty the vegetative body of a fungus. extremes in temperature or pressure and detects acids. chemical signals from damaged tisue. mycorrhizal fungi Fungi that form mutualistic nodes of Ranvier In the peripheral nervous system, omnivore Organism in a food chain that feeds on both relationships with the roots of vascular plants. gaps in the myelin sheath encasing each long axon. plants and animals. nondisjunction Failure of homologous chromosomes myelin sheath White, fatty material—derived from the or daughter chromosomes to separate during meiosis oncogene Cancer-causing gene. membranes of tightly spiraled cells—that forms a I or meiosis II, respectively. oogenesis Production of eggs in females by the process covering for nerve fibers. nonrandom mating Mating that does not occur on a purely random basis; examples are inbreeding and of meiosis and maturation. myosin Muscle protein making up the thick filaments in sexual selection. open circulatory system Circulatory system, such a sarcomere. It pulls actin to shorten the sarcomere, nonrenewable resources Minerals, fossil fuels, and yielding muscle contraction. other materials present in essentially fixed amounts as that found in a grasshopper, in which a tubular (within the human timescale) in our environment. heart pumps hemolymph through channels and body N nonsister chromatid A tetrad consists of four chromatids. cavities. Only the chromatids belonging to a homologue are operon Group of structural and regulating genes that nasal cavity One of two canals in the nose, separated sister chromatids; the others, belonging to the other function as a single unit. by a septum. homologue, are nonsister chromatids. opportunistic species Species demonstrating a nonvascular plants Bryophytes, or plants that have no life history pattern characterized by exponential native species Indigenous species that have colonized vascular tissue and either occur in moist locations or population growth. Its members are small in size, an area without human assistance. have adaptations for living in dry locations; mosses mature early, have a short life span, produce many are an example. offspring, and provide little or no care to offspring natural history Study of how organisms are influenced notochord Cartilaginous-like, dorsal supporting rod in (e.g., dandelions). by factors such as climate, predation, competition, all chordates sometime in their life cycle; replaced order One of the categories, or taxa, used by and evolution; uses field observations instead of by vertebrae in vertebrates. taxonomists to group species; the taxon above the experimentation. nuclear envelope Double membrane that surrounds family level. the nucleus in eukaryotic cells and is connected to organ Combination of two or more different tissues natural killer (NK) cell Large lymphocyte that causes the endoplasmic reticulum; has pores that allow performing a common function. a virus-infected or cancerous cell to burst. substances to pass between the nucleus and the organ system Group of related organs working cytoplasm. together. natural selection Mechanism of evolution caused nuclease Enzyme that catalyzes decomposition of organelle Small, often membranous compartment in the by environmental selection of organisms most nucleic acids into nucleotides. cytoplasm having a specific structure and function. fit to reproduce; results in adaptation to the nucleic acid Polymer of nucleotides. Both DNA and organic Molecule that always contains carbon and environment. RNA are nucleic acids. hydrogen and often contains oxygen as well. nucleoid Region of a prokaryotic cell where the DNA Organic molecules are associated with living Neandertal Later Homo species (Homo is located. It is not bound by a nuclear envelope. organisms. neandertalensis) with a sturdy build that lived nucleolus In the nucleus, a dark-staining, spherical organism An individual plant, fungi, animal, or single- during the last Ice Age in Europe and the Middle body that produces ribosomal subunits. celled organism. East; hunted large game and left evidence of being nucleosome In the nucleus of a eukaryotic cell, a unit osmosis Diffusion of water across a semipermeable culturally advanced. composed of DNA wound around a core of eight membrane. histone proteins, giving the appearance of a bead on osteocyte Branched bone cell embedded in a calcium- negative feedback Homeostatic mechanism that allows a string of beads. containing extracellular matrix. the body to keep the internal environment relatively nucleotide Monomer of DNA and RNA consisting of a osteoporosis Condition in which bones break easily stable. 5-carbon sugar bonded to a nitrogenous base and a because calcium is removed from them faster than it phosphate group. is replaced. nematocyst In cnidarians, a capsule that contains a nucleus Center of an atom, in which protons and ovary In animals, the female gonad that produces an threadlike fiber, the release of which aids in the neutrons are found; membrane-bound organelle egg and female sex hormones; in flowering plants, capture of prey. within a eukaryotic cell that contains chromosomes the enlarged, ovule-bearing portion of the carpel that and controls the structure and function of the cell. develops into a fruit. nephron Microscopic tubule in a kidney that regulates nutrient Substance in food that performs a ovulation Release of a secondary oocyte from the blood composition by filtration, reabsorption, and physiological function in the body and thus ovary via the bursting of a mature follicle. If secretion; site of urine production. contributes to good health. fertilization occurs, the secondary oocyte becomes an egg. nephron loop Portion of a nephron between the ovule In seed plants, a structure that contains the proximal and distal convoluted tubules; functions in female gametophyte and has the potential to water reabsorption. develop into a seed. oxidation Loss of one or more electrons from an atom nerve Bundle of long axons outside the central nervous or a molecule; in biological systems, generally the system. loss of hydrogen atoms. nerve impulse Electrochemical changes that take place across the axon’s membrane; the action potential. nervous system Organ system, consisting of the brain, spinal cord, and associated nerves; coordinates the other organ systems of the body. nervous tissue Tissue that contains nerve cells (neurons), which conduct impulses, and neuroglia, which support, protect, and provide nutrients to neurons. Nervous tissue coordinates the functions of
Glossary G-11 P phospholipid Molecule that forms the phospholipid plasmid Self-duplicating ring of accessory DNA in the bilayer of plasma membranes. It has a polar, cytoplasm of a bacterial cell. paleontology Study of the fossil record, which yields hydrophilic head bonded to two nonpolar, knowledge about the history of species and therefore hydrophobic tails. plasmodesmata (sing., plasmodesma) In plants, of life on Earth. cytoplasmic strands that extend through pores in the photoautotroph Organism able to synthesize organic cell wall and connect the cytoplasm of two adjacent pancreas Internal organ that produces digestive molecules by using carbon dioxide as a carbon cells. enzymes and the hormones insulin and glucagon. source and sunlight as an energy source. platelet In blood, a formed element that is necessary to pancreatic amylase Enzyme that digests starch to photoperiod Ratio of the lengths of day and night over blood clotting; also called thrombocytes. maltose. a 24-hour period, which affects the physiology and behavior of organisms. pleiotropy Inheritance pattern in which one gene pancreatic islets Masses of cells that constitute the affects many phenotypic characteristics of the endocrine portion of the pancreas; also called the photoreceptor Sensory receptor that responds to light individual. islets of Langerhans. stimuli. point mutation Alteration in a gene due to a change in parasitism Interaction in which one species (the photosynthesis Process occurring usually within a single nucleotide. The results of this mutation vary. parasite) obtains nutrients from another species (the chloroplasts whereby chlorophyll-containing host) but does not usually kill the host. organelles trap solar energy to reduce carbon dioxide polar In chemistry, bond in which the sharing of to carbohydrates. electrons between atoms is unequal. parasympathetic division Division of the autonomic system that is active under normal conditions; uses photosystem Photosynthetic unit in which solar energy pollen grain In seed plants, structure that is derived acetylcholine as a neurotransmitter. is absorbed and high-energy electrons are generated; from a microspore and develops into a male contains a pigment complex and an electron gametophyte. parathyroid gland Gland embedded in the posterior acceptor; occurs as PS (photosystem) I and PS II. surface of the thyroid gland; produces parathyroid pollen tube In seed plants, tube that forms when a hormone. phototropism Growth response of plant stems to light; pollen grain lands on the stigma and germinates. The stems demonstrate positive phototropism. tube grows, passing between the cells of the stigma parathyroid hormone (PTH) Hormone, secreted by and the style to reach the egg inside an ovule, where the four parathyroid glands, that increases the blood photovoltaic (solar) cell Energy-conversion device that fertilization occurs. calcium level and decreases the phosphate level. captures solar energy and converts it to electrical current. pollination In gymnosperms, the transfer of pollen parthenogenesis Development of an egg cell into a from pollen cone to seed cone; in angiosperms, the whole organism without fertilization. phylogenetic tree Diagram that indicates common transfer of pollen from anther to stigma. ancestors and lines of descent among groups of passive immunity Protection against infection acquired organisms. pollution Any environmental change that adversely by transfer of antibodies to a susceptible individual. affects the lives and health of living organisms. phylogeny Evolutionary history of a group of pathogen Disease-causing agent, such as viruses, organisms. polygenic The contribution of two or more genes to a parasitic bacteria, fungi, and animals. phenotype. phylum One of the categories, or taxa, used by pedigree Chart showing a family’s history with regard taxonomists to group species; the taxon above the polymer Macromolecule consisting of covalently to a particular genetic trait. class level. bonded monomers. For example, a polypeptide is a polymer of monomers called amino acids. pelvic inflammatory disease (PID) Latent infection of phytochrome Photoreversible leaf pigment involved in chlamydia or gonorrhea in the uterine tubes or the photoperiodism and other responses of plants, such polymerase chain reaction (PCR) Technique that uses vasa deferentia. as etiolation. the enzyme DNA polymerase to produce billions of copies of a particular piece of DNA. penis Male copulatory organ; in humans, the male pith Parenchyma tissue in the center of some eudicot organ of sexual intercourse. stems and roots. polyp Small growth that arises from the epithelial lining of the large intestine. pepsin Enzyme, secreted by gastric glands, that digests pituitary gland Small gland that lies just inferior to the proteins to peptides. hypothalamus; consists of the anterior and posterior polypeptide Polymer of many amino acids linked by pituitary, both of which produce hormones. peptide bonds. peptide Two or more amino acids joined together by covalent bonding. placebo Treatment that contains no medication polyribosome String of ribosomes simultaneously but appears to be the same treatment as that translating regions of the same mRNA strand during peptide bond Type of covalent bond that joins two administered to the test groups in a controlled study. protein synthesis. amino acids. placenta Organ formed during the development of polysaccharide Polymer made from sugar monomers. peptide hormone Type of hormone that is a protein or placental mammals from the chorion and the uterine The polysaccharides starch and glycogen are a peptide or is derived from an amino acid. wall; allows the embryo, and then the fetus, to polymers of glucose monomers. acquire nutrients and rid itself of wastes; produces peptidoglycan Unique molecule found in bacterial cell hormones that regulate pregnancy. pons Part of the brain stem located between the midbrain walls. and the medulla oblongata; controls breathing. placental mammal Mammal characterized by the pericycle Layer of cells surrounding the vascular tissue presence of a placenta during the development of the population Group of individuals of the same species of roots; produces lateral roots. offspring. occupying a given location at the same time. peripheral nervous system (PNS) Nerves that lie planarian Free-living flatworm with a ladderlike population density Number of individuals per unit area outside the central nervous system. nervous system. (or unit volume) of a particular habitat. peristalsis Rhythmic contractions that propel substances plant Multicellular, usually photosynthetic, organism population genetics Study of gene frequencies and along a tubular structure, such as the esophagus. belonging to the kingdom Plantae. their changes within a population. petal Flower part just inside the sepals; often plants Multicellular, photosynthetic eukaryotes whose portal system Pathway of blood flow that begins conspicuously colored to attract pollinators. life cycle is characterized by having distinct diploid and ends in capillaries, such as the portal system and haploid stages. between the intestines and the liver. pH A logarithmic measure of the hydrogen ion concentration. plasma In vertebrates, the liquid portion of blood, posterior pituitary Portion of the pituitary gland composed of water and proteins with smaller that stores and secretes oxytocin and antidiuretic pH scale Numerical scale ranging from 0 to 14 that quantities of nutrients, wastes, and salts. hormone produced by the hypothalamus. indicates the negative log of the hydrogen ion concentration in a solution. plasma cells B lymphocytes that have been activated to postzygotic isolating mechanism Anatomical or produce antibodies against a specific antigen. physiological difference between two species that pharynx In vertebrates, common passageway for both prevents successful reproduction after mating has food intake and air movement; located between the plasma membrane Membrane surrounding the taken place. mouth and the larynx. cytoplasm; consists of a phospholipid bilayer with embedded proteins. It regulates the entrance and exit potential energy Stored energy as a result of location phenotype Visible expression of a genotype—e.g., of molecules from a cell. or spatial arrangement. brown eyes or attached earlobes. predation Interaction in which one organism (the phloem Vascular tissue that conducts organic solutes in predator) uses another (the prey) as a food source. plants; contains sieve-tube members and companion cells.
G-12 Glossary prediction Step of the scientific process that follows proto-oncogene Normal gene that can become an regulatory gene A gene outside an operon that codes for the formation of a hypothesis and assists in creating oncogene through mutation. a protein that regulates the expression of other genes. the experimental design. protocell Cell-like structure with an outer membrane, release factor Protein complex that binds to a stop prefrontal area In the frontal lobe, association area thought to have preceded the true cell. codon on an mRNA at the A site of the ribosome, that receives information from other association causing termination of the transcription. areas and uses it to reason and plan actions. proton Positive subatomic particle located in the nucleus and assigned one atomic mass unit. renewable resources Resources normally replaced or preparatory (prep) reaction Reaction that oxidizes replenished by natural processes and not depleted pyruvate with the release of carbon dioxide; results protostome Group of coelomate animals in which by moderate use. Examples include solar energy, in acetyl-CoA and connects glycolysis to the citric the first embryonic opening (the blastopore) is biological resources (such as forests and fisheries), acid cycle. associated with the mouth. biological organisms, and some biogeochemical cycles. pressure-flow model Explanation for the transport proximal convoluted tubule Portion of a nephron of sugar by phloem that says that osmotic pressure leading from the nephron capsule where replacement model Proposal that modern humans following active transport of sugar into phloem reabsorption of filtrate occurs. originated only in Africa, then migrated and brings a flow of sap from a source to a sink. supplanted populations of other Homo species in pseudocoelomate Animal, such as a roundworm, with a Asia and Europe about 100,000 years ago; also prezygotic isolating mechanism Anatomical or body cavity incompletely lined by mesoderm. called the out-of-Africa hypothesis. behavioral difference between two species that prevents the possibility of mating. puberty Period of life when secondary sex changes replacement reproduction A measure of population occur in humans; marked by the onset of menses in dynamics in which each person is replaced by only primary motor area In the frontal lobe of the females and sperm production in males. one child in the next generation. cerebrum, area where voluntary commands begin. Each section controls a part of the body. pulmonary artery Blood vessel that takes blood away repressor In an operon, a protein molecule that binds to an from the heart to the lungs. operator, preventing transcription of structural genes. primary productivity The rate at which producers in an ecosystem capture and store energy and organic pulmonary circuit Circulatory pathway between the reproduce To produce a new individual of the same kind. nutrients over a certain length of time. lungs and the heart. reproductive cloning The process that creates a new primary sensory area In the parietal lobe of the pulmonary vein Blood vessel that takes blood to the individual that is genetically identical to the original cerebrum, area where sensory information arrives heart from the lungs. individual. from the skin, skeletal muscles, and joints. reproductive system Organ system that consists of pulse Vibration felt in arterial walls due to expansion of different organs in males and females and specializes primary succession Stage in ecological succession, the aorta following ventricle contraction. in the production of offspring. which involves the creation of new soil. reptiles Terrestrial vertebrates with internal Punnett square Grid used to calculate the expected fertilization, scaly skin, and a shelled egg; include principle Theory that is generally accepted by an results of simple genetic crosses. snakes, lizards, turtles, crocodiles, and birds. overwhelming number of scientists, also called a reservoir In chemical cycling, a source (e.g., fossil law. R fuels, minerals in rocks, and ocean sediments) that is normally unavailable to organisms. prion Infectious particle consisting of protein only and radial symmetry Body plan in which similar parts resource Any component of an environment that no nucleic acid. are arranged around a central axis, like spokes of a supports its organisms; includes food, water, shelter, wheel. and space. producer An organism that makes its own food (an resource partitioning Mechanism that increases the autotroph) and is thus at the base of a food chain. random distribution Spatial distribution of individuals number of niches by apportioning the supply of in a population in which individuals have an equal a resource, such as food or living space, between product Anything that forms as a result of a chemical chance of living anywhere within an area. species. reaction. respiration Sequence of events that results in gas range Portion of the globe where a certain species can exchange between the cells of the body and the progesterone Female sex hormone that helps maintain be found. environment. sexual organs and secondary sex characteristics. respiratory system Organ system consisting of the ray-finned fishes Group of bony fishes with fins lungs, trachea, and other structures; brings oxygen prokaryote Single-celled organism that lacks the supported by parallel bony rays connected by webs into the body and takes carbon dioxide out. membrane-bound nucleus and membranous of thin tissue. responding variable In an experiment, the value that organelles typical of eukaryotes. is obtained as a result of changing the experimental reabsorption Movement of primarily nutrient molecules variable. prokaryotic cell Cell lacking a membrane-bound and water from the contents of the nephron into restriction enzyme Bacterial enzyme that stops nucleus and organelles; the cell type within the blood at the proximal convoluted tubule. viral reproduction by cleaving viral DNA; used to domains Bacteria and Archaea. cut DNA at specific points during production of reactant Substance that participates in a chemical recombinant DNA. promoter A sequence of DNA that is involved in the reaction. retrovirus A virus that uses RNA as its genetic material regulation of gene expression. Located where the and contains the enzyme reverse transcriptase, which RNA polymerase binds prior to transcription. receptor-mediated endocytosis Selective uptake of carries out transcription of the RNA to DNA. molecules into a cell by vesicle formation after ribose Pentose monosaccharide sugar found in RNA. prophase Mitotic phase during which chromatin they bind to specific receptor proteins in the plasma ribosomal RNA (rRNA) Type of RNA found in condenses, so that chromosomes appear. membrane. ribosomes that translates messenger RNAs to Chromosomes are scattered. produce proteins. recessive allele Allele that exerts its phenotypic effect ribosome Structure consisting of rRNA and proteins proprioceptor Sensory receptor that helps the body only in the homozygote. Its expression is masked by in two subunits; site of protein synthesis in the maintain equilibrium and posture by detecting a dominant allele. cytoplasm. changes in the positions of the joints, muscles, and RNA (ribonucleic acid) Nucleic acid produced from bones. recombinant DNA (rDNA) DNA that contains genes covalent bonding of nucleotide monomers that from more than one source. contain the sugar ribose. Three major forms are prosimians Group of primates that includes lemurs, messenger RNA, ribosomal RNA, and transfer RNA. lorises, and tarsiers and may resemble the first red blood cell Erythrocyte; contains hemoglobin and primates to have evolved. carries oxygen from the lungs or gills to the tissues in vertebrates. protein Molecule consisting of one or more polypeptides; a macronutrient in the diet that redox reaction Oxidation-reduction reaction; one is digested to the amino acids used by cells to molecule loses electrons (oxidation) while another synthesize cellular proteins. molecule gains electrons (reduction). proteome Collection of proteins resulting from the reduction Gain of electrons by an atom or a molecule translation of all the genes in an organism’s genome. with a concurrent storage of energy. In biological systems, the electrons are accompanied by hydrogen proteomics Study of the structure, function, and ions. interaction of proteins. reflex Automatic, involuntary response of an organism protist Eukaryotic organisms that are usually single- to a stimulus. celled; members of the kingdom Protista.
Glossary G-13 RNA polymerase During transcription, an enzyme that segmentation Repetition of body units, as in the sodium-potassium pump Carrier protein in the plasma joins nucleotides in a sequence complementary to earthworm. membrane that moves sodium ions out of and that in a DNA template. potassium ions into animal cells; important in nerve semen (seminal fluid) Thick, whitish fluid consisting and muscle cells. root hair Long, slender projection of a root epidermal of sperm and secretions from several glands of the cell that increases the surface area of the root for the male reproductive tract. solute Substance dissolved in a solvent, forming a absorption of water and minerals. solution. semiconservative Duplication of DNA resulting in two root nodule Plant root structure that contains nitrogen- double-helix molecules, each having one parental solution Fluid (the solvent) that contains a dissolved fixing bacteria. and one new strand. solid (the solute). root system Main plant root and all of its lateral (side) semilunar valve Valve resembling a half-moon located solvent Liquid portion of a solution that dissolves a branches. between a ventricle of the heart and its attached solute. vessels. roots System of a plant responsible for absorbing somatic cell Body cell; excludes cells that undergo nutrients and water from the soil, as well as senescence Sum of the processes involving aging, meiosis and become sperm or eggs. providing anchoring to the plant. decline, and eventual death of a plant or plant part. somatic system Portion of the peripheral nervous rotational equilibrium Maintenance of balance when sensory adaptation Decrease in the response to a sensory system that includes the nerves that take the head and body are suddenly moved or rotated; stimulus, usually from overexposure to the stimulus. information about external stimuli from sensory involves the semicircular canals of the inner ear. receptors to the central nervous system and motor sensory neuron Nerve cell that transmits nerve commands away from the central nervous system rough ER Membranous system of tubules, vesicles, impulses to the central nervous system after a to skeletal muscles. and sacs in cells; has attached ribosomes. sensory receptor has been stimulated. speciation Formation of new species due to the roundworm Invertebrate with a cylindrical body sepal Outermost, leaf-like covering of a flower; usually evolutionary process of descent with modification. covered by a cuticle that molts; also has a complete green. digestive tract and a pseudocoelom. Some forms are species Group of similarly constructed organisms free-living in water and soil, and many are parasitic. septum Partition that divides two areas. The septum in capable of interbreeding and producing viable the heart separates the right side from the left side. offspring; organisms that share a gene pool; the RuBP carboxylase (rubisco) Enzyme required for taxon at the lowest level of classification. carbon dioxide fixation (atmospheric CO2 attaches to sex chromosomes Pair of chromosomes that determine RuBP) in the Calvin cycle. the sex of an individual. In humans, females have species richness List of the different species found in a two X chromosomes, and males have an X and a Y community. S chromosome. spermatogenesis Production of sperm in males by the SA (sinoatrial) node Pacemaker; small region of sexual reproduction Form of reproduction that involves process of meiosis and maturation. cardiac muscle tissue that initiates the heartbeat. an input of genetic material from two individuals; increases the genetic variation of the offspring. spinal cord In vertebrates, the nerve cord that is salinization Process in which mineral salts accumulate continuous with the base of the brain and housed in the soil, killing crop plants; occurs when soils in sexual selection Adaptive changes in males and females within the vertebral column. dry climates are irrigated profusely. of a species, often due to male competition and female selectivity, leading to increased fitness. spinal nerve Nerve that arises from the spinal cord. salivary amylase In humans, enzyme in saliva that spindle Microtubule structure that brings about breaks down starch to maltose. shoot system Aboveground portion of a plant consisting of the stem, leaves, flowers, and fruit. chromosomal movement during nuclear division. salivary gland In humans, gland associated with the spleen Large, glandular, lymphatic organ in the mouth that secretes saliva. short tandem repeat (STR) profiling Procedure for analyzing DNA in which PCR and gel upper left abdominal cavity; stores and purifies salt Solid substance formed by ionic bonds that usually electrophoresis are used to create a banding pattern, blood. dissociates into individual ions in water. which is usually unique for each individual; process sponge Invertebrate animal of the phylum Porifera; used in DNA barcoding. pore-bearing filter feeder whose inner body wall is saltwater intrusion Movement of salt water into lined by collar cells. freshwater aquifers in coastal areas where sieve-tube member Cell that joins with others in spongy bone Type of bone that has an irregular, groundwater is withdrawn faster than it is the phloem tissue of plants to provide a means of meshlike arrangement of thin plates of bone. replenished. transport for organic solutes. sporophyte Diploid generation of the life cycle of a plant; produces haploid spores that develop into the saprotroph Organism that secretes digestive enzymes signal transduction pathway A series of reactions that haploid generation. and absorbs the resulting nutrients back across brings about activation and inhibition of intracellular stabilizing selection Outcome of natural selection in the plasma membrane; fungus or bacterium that targets after binding of growth factors. which extreme phenotypes are eliminated and the decomposes the remains of plants, animals, and intermediate (average) phenotype is conserved. microbes in the soil. sinus Cavity into which hemolymph flows and bathes stamen In flowering plants, portion of the flower that the organs in an open circulatory system; also, an consists of a filament and an anther containing sarcomere One of many identical units, arranged air-filled space connected to a nasal cavity. pollen sacs where pollen is produced. linearly in a myofibril, whose contraction produces starch In plants, storage polysaccharide composed of muscle contraction. sister chromatid One of two genetically identical glucose molecules joined in a linear fashion with few chromosomal units that are the result of DNA side chains. saturated fatty acid Fatty acid molecule that replication and are attached to each other at the stem Usually the upright, vertical portion of a plant that lacks double bonds between the carbons of its centromere. transports substances to and from the leaves. hydrocarbon chain. The chain bears the maximum sterility Inability to produce offspring. number of hydrogens possible. skeletal muscle Striated, voluntary muscle tissue that steroid Type of lipid molecule having a complex comprises skeletal muscles; also called striated of four carbon rings—e.g., cholesterol, estrogen, scientific theory Concept supported by a broad range muscle. progesterone, and testosterone. of observations, experiments, and data. steroid hormone Type of hormone that is a lipid and skeletal system Organ system that consists of bones can pass through a cell’s plasma membrane. secondary succession In ecological succession, the and works with the muscular system to protect the stigma In flowering plants, portion of the carpel stage at which there is gradual replacement of body and provide support. where pollen grains adhere and germinate before communities in an area following a disturbance. fertilization can occur. sliding filament model Explanation of muscle stoma (pl., stomata) Small opening between two guard secretion In the cell, release of a substance by contraction based on the movement of actin cells in the epidermis of a leaf through which gases exocytosis from a cell that may be a gland or part of filaments in relation to myosin filaments. pass; serves to minimize water loss. a gland; in the urinary system, movement of certain molecules from blood into the distal convoluted small intestine In vertebrates, portion of the digestive tubule of a nephron, so that they are added to urine. tract that precedes the large intestine; in humans, the duodenum, jejunum, and ileum, which are seed Mature ovule that contains an embryo, with stored responsible for most digestion and absorption of the food enclosed in a protective coat. resulting nutrients. smooth ER Membranous system of tubules, vesicles, and sacs in eukaryotic cells; lacks attached ribosomes.
G-14 Glossary stomach In vertebrates, thick-walled organ of the taxon (pl., taxa) Group of organisms that fills a tonsils Partially encapsulated lymphatic nodules in the digestive tract that mixes food with gastric juices to particular classification category. pharynx. form chyme, which enters the small intestine. taxonomy Branch of biology concerned with totipotent Cell that has the full genetic potential of the stroke Condition resulting when an arteriole in the identifying, naming, and classifying organisms. organism, including the potential to develop into a brain bursts or becomes blocked by an embolus; complete organism. cerebrovascular accident. technology Application of scientific knowledge for a practical purpose. trace mineral Essential inorganic nutrient (such as stroma Fluid-filled space within a chloroplast that zinc, iron, copper, iodine, or selenium) needed in a contains enzymes involved in the synthesis of telomere Long, repeating DNA base sequence at the relatively small quantity in the daily diet of humans carbohydrates during photosynthesis. ends of chromosomes; functions as a cap and keeps to regulate metabolic activities and maintain good chromosomes from fusing with each other. health. style Elongated, central portion of the carpel between the ovary and stigma. telophase Mitotic phase during which daughter cells trachea (pl., tracheae) In tetrapod vertebrates, air tube are located at each pole. (windpipe) that runs between the larynx and the subsidence Gradual settlement of a portion of the bronchi. Earth’s surface. template Parental strand of DNA that serves as a guide for the complementary daughter strand produced tracheid In vascular plants, type of cell in xylem that substrate Reactant in a reaction controlled by an during DNA replication. has tapered ends and pits through which water and enzyme. minerals flow. tendon Strap of fibrous connective tissue that connects supergroup High-level taxonomic groups just skeletal muscle to bone. trans fat A form of unsaturated fatty acid in which the below the domain level; used for classification of hydrogen atoms on the carbon chain are on opposite eukaryotes. terrestrial ecosystem A biome, such as a tundra, sides of the double bond. taiga, temperate forest, tropical grassland (savanna), surface-area-to-volume ratio Ratio of a cell’s outside temperate grassland (prairie), desert, or tropical rain transcription Process whereby a DNA strand serves as area to its internal volume. forest. a template for the formation of mRNA. survivorship Term used to describe the probability testcross Cross between an individual with the transcription factor In eukaryotes, protein required for of newborn individuals of a cohort surviving to dominant phenotype and an individual with the the initiation of transcription by RNA polymerase. particular ages and its influence on population size. recessive phenotype. The resulting phenotypic ratio indicates whether individual with the dominant transduction Transport of DNA between bacterial cells sustainable society A society that is able to continue phenotype is homozygous or heterozygous. by a bacteriophage. to provide the same goods and services for future generations while preserving biodiversity. testis (pl., testes) Male gonad that produces sperm and transfer rate Amount of a nutrient that moves from the male sex hormones. one component of the environment to another within symbiotic Type of relationship that occurs when two a specified period of time. different species live together in a unique way. It testosterone Male sex hormone that helps maintain may be beneficial, neutral, or detrimental to one or sexual organs and secondary sex characteristics. transfer RNA (tRNA) Type of RNA that transfers a both species. particular amino acid to a ribosome during protein tetany Severe twitching caused by involuntary synthesis. At one end, tRNA binds to the amino acid, sympathetic division Division of the autonomic system contraction of the skeletal muscles due to a low and at the other end, it has an anticodon that binds to that is active when an organism is under stress; uses blood calcium level. an mRNA codon. norepinephrine as a neurotransmitter. tetrad Association of two homologous chromosomes, transformation Taking up of extraneous genetic sympatric speciation Origin of new species without each having two sister chromatids that are joined material from the environment by a bacterial cell. prior geographic isolation of a population. during meiosis; also called bivalent. transgenic organism An organism that has had a gene synapse Region of close proximity between the axon thalamus In vertebrates, portion of the diencephalon from another species inserted into its genome. terminal of one neuron and a dendrite or cell body of that receives and passes on to the cerebrum all another neuron. sensory input except smell. translation Process whereby ribosomes use the sequence of codons in mRNA to produce a synapsis Pairing of homologous chromosomes during therapeutic cloning Cloning done to create mature polypeptide with a particular sequence of amino meiosis I. cells of various types; also used to learn about acids. specialization of cells and provide cells and tissue to synaptic cleft Small gap between parts of neurons at a treat human illnesses. translocation The movement of a chromosomal synapse. segment from one chromosome to another, thermoacidophile Type of archaea that lives in hot, nonhomologous chromosome or the exchange of synovial joint Freely moving joint in which two bones, acidic, aquatic habitats (such as hot springs) or near segments between nonhomologous chromosomes, joined by ligaments, are separated by a fluid-filled hydrothermal vents. leading to abnormalities—e.g., Down syndrome. cavity. thigmotropism Growth response of plants to touch. transpiration Plant’s loss of water to the atmosphere, syphilis Bacterial STD with three stages separated by three-domain system System of classification that mainly through evaporation at leaf stomata. latent periods; may result in blindness, cause birth defects or stillbirth, and affect the cardiovascular recognizes three domains: Bacteria, Archaea, and transposon DNA sequence capable of randomly and/or nervous system. Eukarya. moving from one site to another in the genome. thylakoid Flattened sac within a granum whose systematics Study of the diversity of organisms to membrane contains chlorophyll and where the light trichomoniasis Sexually transmitted disease caused by classify them and determine their evolutionary reactions of photosynthesis occur. the parasitic protozoan Trichomonas vaginalis. relationships. thymine (T) One of four nitrogen-containing bases in nucleotides composing the structure of DNA; pairs triglyceride Molecule composed of glycerol and three systemic circuit Circulatory pathway of blood flow with adenine. fatty acids that is the main component of fats and between the tissues of the body and the heart. thymus Lymphatic organ involved in the development oils. and functioning of the immune system. T cells systole Contraction period of a chamber of the heart mature in the thymus. trophic level A level of nourishment within a food during the cardiac cycle. thyroid gland Large gland in the neck; produces chain or web. several important hormones, including thyroxine, T triiodothyronine, and calcitonin. tropism In plants, a growth response toward or away tight junction Junction between cells in which from a directional stimulus. T lymphocyte (T cell) Lymphocyte that matures in the adjacent plasma membrane proteins join to form an thymus and exists in four varieties, one of which impermeable barrier. trypsin Enzyme secreted by the pancreas that breaks kills antigen-bearing cells outright. tissue Group of similar cells combined to perform a down proteins to peptides. common function. T-cell receptor (TCR) On the T-cell surface, tissue culture Process of growing tissue artificially, tumor Group of cells derived from a single, mutated receptor consisting of two antigen-binding peptide usually in a liquid medium in laboratory glassware. cell that has repeatedly undergone cell division. chains; associated with a large number of other Benign tumors remain at their site of origin, while glycoproteins. Binding of antigen to the TCR, usually malignant tumors metastasize. in association with MHC, activates the T cell. tumor suppressor gene Gene that codes for a protein that ordinarily suppresses cell division. Inactivity can lead to a tumor.
Glossary G-15 tunicate Type of primitive invertebrate chordate. V villus (pl., villi) Small, fingerlike projection on the wall Turner syndrome Condition caused by the inheritance of the small intestine. vaccine Substance prepared from a pathogen or its of a single X chromosome. products in such a way that it can promote active viroid Infectious strand of RNA devoid of a capsid and immunity without causing disease. much smaller than a virus. U vagina Female sex organ that serves as the birth canal vitamin Organic compound required in the human diet. umbilical cord Cord connecting the developing embryo during pregnancy. Vitamins are often part of coenzymes in the body. and then the fetus to the placenta, through which blood vessels pass. valence shell Outer energy shell of an atom. vocal cord In the human larynx, flexible bands of vascular bundle In plants, primary phloem and connective tissue that create sounds when they vibrate. uniform distribution Spatial distribution of individuals in a population in which individuals are dispersed primary xylem enclosed by a bundle sheath. W uniformly through the area. vascular plants Plants that have vascular tissue (xylem white blood cell Leukocyte, of which there are several unsaturated fatty acid Fatty acid molecule that has and phloem); include seedless vascular plants types, each having a specific function in protecting one or more double bonds between the carbons of its (e.g., ferns) and seed plants (gymnosperms and the body from invasion by foreign substances and hydrocarbon chain. The chain bears fewer hydrogens angiosperms). organisms. than the maximum number possible. vascular tissue Tissue in plants that provides transport and support; consists of xylem and phloem. wood Secondary xylem that builds up year after year in uracil (U) Pyrimidine base that replaces thymine in vector Piece of DNA that can have a foreign DNA woody plants, becoming annual rings. RNA; pairs with adenine. attached to it. A common vector is a plasmid. vein Blood vessel that arises from venules and X ureter Tubular structure conducting urine from the transports blood toward the heart. kidney to the urinary bladder. vena cava (pl., venae cavae) Large, systemic vein that X inactivation Process in females that causes one of returns blood to the right atrium of the heart; either the two X chromosomes to condense into an inactive urethra Tubular structure that receives urine from the the superior or inferior vena cava. form called a Barr body. An example of epigenetic bladder and carries it to the outside of the body. ventricle Cavity in an organ, such as a lower chamber inheritance. of the heart or a ventricle in the brain. urinary bladder Organ where urine is stored. venule Vessel that takes blood from capillaries to a X-linked Allele that is located on an X chromosome urinary system Organ system consisting of the kidneys vein. but related to a trait that has nothing to do with sex vertebrate Chordate in which the notochord is replaced characteristics. and urinary bladder, along with other structures that by a vertebral column made of cartilage or bone. transport urine; rids the body of wastes and helps vesicle Small, membrane-bound sac that stores xylem Vascular tissue that transports water and mineral regulate the fluid level and chemical content of the substances in a cell. solutes upward through the plant body. It contains blood. vessel element Cell that joins with others to form a vessel elements and tracheids. urine Liquid waste product made by the nephrons major conducting tube in xylem. of the vertebrate kidney through the processes of vestigial structure Anatomical feature that is fully Z filtration, reabsorption, and secretion. developed in one group of organisms but reduced uterus In mammals, expanded portion of the female and nonfunctional in other, similar groups. zygote Diploid cell formed by the union of two reproductive tract through which eggs pass to the gametes; the product of fertilization. environment or in which an embryo develops and is nourished before birth.
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