Biodiversity and its Conservation 157 Ex-situ Conservation When there are situations where an animal or plant endangered or threatened and needs urgent measures to save it from extinction; It needs ex-situ (off site) conservation. • The threatened animals and plants are taken out from their natural habitat and placed in special setting, where they can be protected and given special care. • Botanical gardens, zoological parks and wildlife safari parks serve this purpose. • The gametes of threatened species are preserved in viable and fertile conditions using cryopreservation techniques. • Commercially important plants can be kept for long periods using tissue culture methods or in seed banks. International Efforts for Biodiversity Conservation • The earth summit — It was the historic convention on Biological Diversity, held in Rio de Janeiro in 1992. — It called upon all the nations to take appropriate measures for (i) Conservation of biodiversity, and (ii) Sustainable utilisation of the benefits of biodiversity. • The world summit — It was held in 2002 in Johannesburg, South Africa. — 190 countries pledged their commitment to achieve a significant reduction in the current rate of biodiversity loss at global, regional and local levels by 2010. Very Short Answer Type Questions 1. India has more than 50,000 strains of rice. Mention the level of biodiversity it represents. Ans. Genetic diversity. 2. Name the type of biodiversity represented by the following: (a) 50,000 different strains of rice in India. (b) Eustuaries and alpine meadows in India. Ans. (a) Genetic diversity. (b) Ecological diversity. 3. Name the type of biodiversity represented by the following: (a) 1000 varieties of mangoes in India. (b) variation in terms of potency and concentration of reserpine in Rauwolfia vomitoria growing in different regions of Himalayas.
158 Biology-XII Ans. (a) Genetic diversity (b) Genetic diversity. 4. Identify ‘a’ and ‘b’ in the figure given below representing appropriate number of major vertebrate taxa. Ans. (a) Mammals (b) Amphibians 5. Name the three important components of biodiversity. Ans. Genetic diversity, Species diversity and Ecological diversity. 6. Who popularised the term biodiversity? What does it mean? Ans. Edward Wilson; Biodiversity means totality of genes, species and ecosystem of a region. 7. Habitat loss and fragmentation has caused severe damage to a particular type of ecosystem. Name it. Ans. Tropical rain forests. 8. What is the result obtained when we compare the relationship between species richness and area for wide variety of taxa? Ans. Rectangular hyperbola. 9. Why is India considered as one of the 12 megadiversity centres of the world? Ans. India has only 2.4 per cent of the world’s land area but shares 8.1 per cent of the global species diversity. 10. What trend is observed in respect of species diversity when we move from equator to poles? Ans. In general, species diversity decreases as we move away from the equator towards poles. 11. Which region is considered as the one with highest biodiversity on earth? What is the popular name given to such region forests? Ans. Amazonian rain forests; they are also called the ‘Lungs of the planet’. 12. What was the phenomenon observed by Alexander von Humboldt regarding species-area relationship? Ans. He observed that within a region species richness increased with increasing explored area, but only upto a limit.
Biodiversity and its Conservation 159 13. Ecologists have discovered that value of ‘Z’ lies in range of 0.1 to 0.2 regardless of taxonomic group or region. When will the slope of line steeper in species-area relationship? Ans. Slope of line is much steeper if one analyses the species-area relationship among very large areas like entire continents. 14. Where do a large number of rare and threatened plants in Meghalaya find their last refuge? Ans. Sacred grove in Khasi and Jaintia hills in Meghalaya. 15. Define cryopreservation. Why is it useful in conserving biodiversity? Ans. Cryopreservation is a method of preserving materials (such as gametes) at ultra low temperature (i.e. in liquid nitrogen at – 196°C). It is done to preserve the gametes of threatened species in viable and fertile condition for long periods. 16. What is the global species diversity according to Robert May? Ans. About 7 million. 17. Name the Indian hotspots of biodiversity. Ans. (i) Western Ghats and Sri Lanka (ii) Indo-Burma and (iii) Himalayas. 18. What is meant by endemism? Ans. It refers to the occurrence of certain species in a particular region which are not found anywhere else. 19. What are alien species? Ans. Alien/exotic species are those species which are new to a geographical area or which are not native to that area. 20. What are seed banks? Ans. Seed banks refer to the collection of seeds of various strains of commercially important plants that are kept viable for long periods. 21. About 200 species of cichlid fish became extinct when a particular fish was introduced in Lake Victoria of Africa. Name the invasive fish. Ans. Nile perch. 22. Name the unlabelled ‘a’ and ‘b’ of the pie chart given below representing the global biodiversity of invertebrates showing their proportionate number of species of major taxa. Crustaceans Other b animal groups a Ans. a—Insects; b—Molluscs.
160 Biology-XII 23. Name the unlabelled ‘a’ and ‘b’ of the pie chart representing the biodiversity of plant showing their proportionate number of species of major taxa. Mosses Ferns ab Lichens Ans. a—Fungi; b—Angiosperms. 24. Name the unlabelled areas ‘a’ and ‘b’ of the pie chart representing biodiversity of vertebrates showing the proportionate number of species of major taxa. Mammals a Birds b Reptiles Ans. a—Fishes; b—Amphibians. Short Answer Type Questions (Type-I) 1. Why certain regions have been declared as biodiversity “hot spots” by environmentalists of the world? Name any two “hot spot” regions of India. Ans. — H ot spots of biodiversity are the regions with very high levels of species richness and high degree of endemism. — Environmentalists are in the opinion that the protection of hot spots could reduce the ongoing mass extinction by almost 30 per cent. — Two hot spot regions of India are: Western Ghats and Sri Lanka, and Indo-Burma. 2. Giving two reasons, explain why there is more species biodiversity in tropical latitudes than in temperate ones? Ans. (i) T emperate regions have undergone frequent glaciations in the past which killed most of the species. But species continued to flourish and evolve undisturbed for several years in the tropical regions as no such disturbances occurred there. (ii) Tropical environments are less seasonal, relatively more constant and predictable, such environment promote niche specialisation and lead to a greater species diversity. (iii) As more solar energy is available in the tropics, which contributes to higher productivity and biodiversity in the tropics. (Any two reasons)
Biodiversity and its Conservation 161 3. List the features that make a stable biological community. Ans. (i) A stable community does not show too much of variation in productivity from year to year. (ii) A stable community is either resistant or resilient to occasional disturbances (natural or man made). (iii) It must be resistant to invasions by alien species. 4. Alien species are a threat to native species. Justify taking examples of an animal and a plant alien species. Ans. — T he introduction of Nile Perch into Lake Victoria in East Africa, led to the extinction of more than 200 species of cichlid fish in the lake. — Parthenium (carrot grass) introduced to our country have become invasive and caused environmental damage, and posing a threat to the native species. 5. What is meant by “alien species” invasion? Name one plant and one animal alien species that are a threat to our Indian native species. Ans. — The introduction of an exotic species (i.e. the species from outside) is called alien species invasion. — Alien plant species – Parthenium; animal species – African catfish (clarias gasiepenus). 6. “Stability of a community depends on its species richness”. Write how did David Tilman show this experimentally? Ans. — David Tilman had shown the following features through his ecological experiments using outdoor plots. — The plots with more species showed less year to year variation in total biomass. — The plots with increased diversity showed higher productivity and greater stability. 7. List any four techniques where the principle of ex-situ conservation of biodiversity has been employed. Ans. Protected maintenance of threatened species in (i) Zoological parks, (ii) Botanical gardens, (iii) Cryopreservation of gametes and (iv) tissue culture propagation. 8. Mention the kind of biodiversity of more than a thousand varieties of mangoes in India represent. How is it possible? Ans. Genetic diversity; It is due to genetic variation shown by the mango plants. The genetic variations arise due to recombination and mutation. 9. Why are sacred groves highly protected? Ans. In many cultures, tracts of forests (called sacred groves) were set aside, and all the trees and wildlife within were venerated and given total protection. 10. Suggest two practices giving one example of each, that help protect rare and threatened species. Ans. (i) National Parks e.g. Gir National Park for lions. (ii) Seed Banks e.g. Keeps seeds of different genetic strains of commercially important plants in live condition.
162 Biology-XII 11. What is the significance of the slope of regression in a species-area relationship? Ans. — T he slope of regression line are amazingly similar regardless of the taxonomic group of the region; it lies in the range of 0.1 to 0.2. — The line is much steeper (with Z values being in the range of 0.6 to 1.2) if one analyses the species-area relationships for very large area; The steepness of the line indicates species richness. 12. What are the major causes of species losses in a geographical region? Ans. (i) Habitat loss and fragmentation. (ii) Over-exploitation of natural resources (iii) A lien species invasions, which compete with the native species and cause their extinction. (iv) Co-extinction of associated species in an obligatory way. 13. What are sacred groves? What is their role in conservation? Ans. — S acred groves are tracts of forest set aside where all the trees and wildlife within are venerated and given total protection. — These groves provide protection to many endemic species which are rare or have become extinct elsewhere, can be seen to flourish here. 14. Among the ecosystem services are control of foods and soil erosion. How is this achieved by the biotic components of the ecosystem? Ans. — Forests control floods by trapping and absorbing the rain water and slowly releasing it later. — The roots of plants hold the soil particles firmly and prevent soil erosion. — The green cover protects the soil from the direct impact of rain drops that cause soil erosion. 15. The species diversity of plants (22 per cent) is much less than that of animals (72 per cent). What could be the explanations to how animals achieved greater diversification? Ans. — Animals are mobile, hence have moved to diverse habitats. — As a result more evolutionary changes occurred in animals than in case of plants, which are unable to move from their place. 16. Can you think of a situation where we deliberately want to make a species extinct? How would you justify it? Ans. — W hen a species becomes nuisance, it needs to be made extinct deliberately. — However, such extinction will not be justified because a species which seems to be a nuisance today, may prove useful in the future. — Secondly, loss of a species from the ecosystem will upset the food chain and functioning of the ecosystem. 17. Enlist the three levels of biological diversity with the help of suitable examples. Ans. (i) G enetic diversity. It is the variations in the genes and their alleles in the same species, e.g. India has more than 50,000 genetically different strains of rice and 1000 varieties of mango.
Biodiversity and its Conservation 163 (ii) Species diversity. It is the variation in the number and richness of the species of a region, e.g. Amphibian species are rich in number in Western Ghats than in the Eastern Ghats. (iii) E cological diversity. It is the variety in the types of ecosystems in a region. e.g. deserts, rainforests, wetlands etc. 18. How many species of plants and animals have been recorded to occur on Earth so far according to IUCN (2004)? What is global species diversity according to Robert May? Ans. — I UCN (2004) has described slightly more than 1.5 million species of plants and animals. — A ccording to Robert May’s estimate the global species diversity is about 7 million. 19. Conventional taxonomic methods are not suitable for identifying microbial species and many species are simply not culturable under laboratory conditions. Why is this a big limitation in the identification of prokaryotes? Ans. If we accept biochemical or molecular criteria for delineating species for this group, then these have to be obtained in pure form in a culture, which becomes difficult, when a species is not culturable under laboratory conditions. 20. Explain co-extinction with a suitable example. Ans. Co-extinction refers to the disappearance of a species with extinction of another species of plant or animal with which it was associated in an obligatory way, e.g., extinction of a plant species, when its pollinator species become extinct. 21. Study the pie-diagram and answer the questions which follows: What do A, B, C and D represent in these diagrams? C Ferns and allies Other animal groups A Angiosperms Molluscs D B Algae Lichens Invertebrates Taxao of plants Ans. A—Crustaceans B—Insects C—Mosses D—Fungi 22. What are the three basic arguments put forward regarding conservation of biodiversity? Ans. Narrow Utilitarian Aspect—Human derive direct benefit from nature in the form of food, firewood, medicine etc. — Nations have rich biodiversity can expect to reap enormous benefits.
164 Biology-XII Broad Utilitarian Aspect. Biodiversity plays a major role in the ecosystem services that nature provide viz., oxygen availability, pollination, aesthetic pleasure etc. Ethical Aspect. Each species has its own intrinsic value. It is our moral duty to take care of well-being of plants and animals. We must conserve the present for the future of our children. 23. Hot spots are the regions of exceptionally high biodiversity. But they have become regions of accidental habitat loss too. Name the three “hot spots” of our country. Why are they called “hot spot”? Ans. — Three hot spots of biodiversity of India are: (i) Western Ghats and Sri Lanka (ii) Indo-Burma and (iii) Himalaya. — They are called hot spots as they show: (i) high level of species richness (ii) high degree of endemism. 24. Study the diagram of the earth given below. Give the name of the pattern of biodiversity therein. Suggest any two reasons for this type of occurrence. Pole Decreases Biodiversity Increases 0˚ 0˚ Pole Ans. — It shows ‘latitudinal gradients in biodiversity distribution on the Earth.’ — Such a gradient is due to the following reasons. (i) tropical latitudes have remained undisturbed for millions of years and thus, had a long evolutionary time for species diversification. (ii) tropical environments are less seasonal, so more constant and predictable. 25. Sometimes introduction of an exotic species upsets native species of the ecosystem. Substantiate the statement with two examples from India. Ans. (i) The invasive weed species like Parthenium (carrot grass), Lantana and Eichhornia (water hyacinth) have posed threat to our native species. (ii) The illegal introduction of the African catfish (Clarias gariepinus) is posing threat to the indigenous catfishes in our rivers. 26. Describe any two factors responsible for loss of biodiversity. Ans. (i) Habitat loss and fragmentation — When large habitats are broken up into smaller fragments due to various human activities, the animals requiring large territories (e.g., some mammals and birds) are badly affected and their populations decline.
Biodiversity and its Conservation 165 (ii) Over-exploitation — When need of a resource becomes greed, it leads to depletion of the resource. e.g. Over-exploitation of stellar’s sea cow, passenger pigeon led to their extinction. 27. What is biodiversity? How is it a matter of concern now? Ans. — Biodiversity refers to the totality of genes, species and ecosystems of a region. — It is a matter of concern because the biodiversity is important for our survival and well-being of this planet. Short Answer Type Questions (Type-II) 1. There are many animals that have become extinct in the wild, but continue to be maintained in zoological parks. (a) What type of biodiversity conservation is observed in this case? (b) Explain any other two ways which help in this type of conservation. Ans. (a) Ex situ conservation. (b) — The gametes of threatened species are preserved in viable and fertile conditions using cryopreservation technique. — The threatened species of animals can be maintained in wild life safari parks. 2. The following graph shows the species – area relationship. Answer the following question as directed. (a) Name the naturalist who studied the kind of relationship shown in the graph. Write the observations made by him. (b) Write the situations as discovered by the ecologists when the values of ‘Z’ (slope of the line) lies between (i) 0.1 and 0.2 (ii) 0.6 and 1.6 (c) When would the slope of the line ‘b’ become steeper? Ans. (a) A lexander von Humboldt; He observed that within a region species richness increased with increasing explored area, but only upto a limit. (b) (i) Explored area is very small; (ii) Explored area is very large. (c) When the area exhibit species richness.
166 Biology-XII 3. Since the origin of life on Earth, there were five episodes of mass extinction of species. (a) How is the ‘Sixth Extinction’ presently in progress different from the previous episodes? (b) Who is mainly responsible for ‘Sixth Extinction’? (c) List any four points that can help to overcome this disaster. Ans. (a) It is 100 – 1,000 times faster than the previous episodes. (b) Our activities are responsible for this faster rate. (c) (i) Checking of deforestation (ii) Planting of trees (iii) Slowing down of human population growth, and (iv) Control on pollution. 4. Many plant and animal species are on the verge of their extinction, because of loss of forest land by indiscriminate use by the humans. As a biology student what method would you suggest along with its advantages that can protect such threatened species from getting extinct? Ans. (i) B iodiversity rich regions should be legally protected as biosphere reserves, national parks and sanctuaries. (ii) — The threatened species are taken out from their natural habitat and placed in special settings, where they can be protected and given special care. — B otanical gardens, zoological parks and wildlife safari parks serve this purpose. (iii) The gametes of threatend species are preserved in viable and fertile conditions using cryopreservation techniques. 5. (a) “India has greater ecosystem diversity than Norway.” Do you agree with the statement? Give reasons in support of your answer. (b) Write the difference between genetic biodiversity and species biodiversity that exists at all the levels of biological organisation. Ans. (a) Yes, India has greater ecosystem diversity than Norway. It is because India is located in tropical region while Norway lies in temperate region. (b) Genetic diversity is the variations in the genes and their alleles in the same species. e.g. The medicinal plant growing in different Himalayan ranges show genetic variation in terms of potency and concentration of the active chemical (reserpine) that the plant produce. Whereas species diversity in the variations in the number and richness of species of a region. 6. How do ecologists estimate the total number of species present in the world? Ans. — Biologists make a statistical comparison of the temperate-tropical species richness of an exclusively studied group of insects and extrapolate this ratio to other groups of animals and plants to come up with a gross estimate of the total number of species on earth. — Some extreme estimates range from 20 to 50 million, but more conservative and scientifically sound estimate made by Robert May places the global species diversity at about 7 million.
Biodiversity and its Conservation 167 7. Why are biologists not sure about the number of species of prokaryotes? Ans. Biologists are not sure about the number of prokaryotic species because: (i) The conventional methods are not suitable for identifying microbial species. (ii) Many species of these are not culturable under laboratory conditions. (iii) If we accept biochemical or molecular criteria for delineating species for this group, then their diversity alone might run into millions. 8. Describe with example the latitudinal gradient of biodiversity. Ans. — In general species diversity decreases as we move away from the equator towards the poles. — Tropics (lattitude range of 23.5°N to 23.5°S) harbour more species than temperate or polar areas. — Columbia located near the equator has nearly 14,000 species of birds, while New York at 41°N has 105 species and Greenland at 71°N only 56 species. — India, with much of its land area in the tropical latitude, has more than 1,200 species of birds. — The number of species of vascular plants in tropics is about ten times more than that of temperate forests. — The Amazon rainforest in South America has the greatest biodiversity on earth; it harbours about 40,000 species of plants, 1,25,000 species of insects, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of reptiles and more than 1,25,000 of invertebrates. 9. Differentiate between In-situ and Ex-situ approaches of Conserving biodiversity. Ans. In-situ Conservation Ex-situ Conservation (i) It is an approach of conservation (i) It is an approach of protecting and protection of the whole the endangered species of plants ecosystem and its biodiversity at or animal by removing it from the all levels in order to protect the threatened habitat and placing threatened species. under human care. (ii) Endangered species is protected (ii) The endangered species is in its natural habitat. protected in places outside their natural habitats. e.g., National parks, wildlife e.g., Botanical gardens, zoological sanctuaries, Biosphere reserves. park, seed banks etc. 10. What are exotic species? Ans. Exotic/alien species are those species which are new to a geographical area or which are not native to that area. 11. A particular species of wild cat is endangered. In order to save them from extinction, which is a desirable approach in-situ or ex-situ? Justify your answer and explain the difference between the two approaches.
168 Biology-XII Ans. Ex-situ conservation is a desirable approach, in which the endangered species of wild cat is taken out from the natural habitat and placed in special setting (such as zoological park) where it is given special care and its progeny can be increased through breeding. 12. What are (i) alien species invasion and (ii) loss of habitat and fragmentation considered to be the major cause of loss of biodiversity? Explain with the help of one example each. Ans. (i) T he alien species become invasive and cause a decline or extinction of indigenous species. e.g., Nile Perch introduced into Lake Victoria led to extinction of more than 200 species of cichlid fish in the lake. (ii) Habitat loss and fragmentation deprive the organisms of their natural home and hence leads to their extinction. — Fragmentation of habitats affects many mammal and bird species which require large territories or exhibit migratory habits, e.g., clearing of Amazen rain forests have cause decline of many mammal and bird species. Long Answer Type Questions 1. (a) Why should be conserve biodiversity? How can we do it? (b) Explain the importance of biodiversity hot spots and sacred groves. Ans. (a) These are two approaches for conservation of biodiversity i.e., (i) I n situ conservation (on site conservation) e.g. National parks, wildlife santuaries, Biosphere reserves and (ii) ex-situ conservation (off site conservation) e.g. Botanical gardens, zoo, seed/pollen banks, gene banks etc. (b) Biodiversity hot spots are regions with high level of species richness and high degree of endemism, protection of these regions can reduce the ongoing extension by almost 30 per cent. Sacred groves are the tracts of forests, where all the trees and wildlife within are venerated and given total protection. 2. Who proposed the Rivet-Popper hypothesis of species diversity in the ecosystem? Explain the hypothesis. Ans. — Rivet-Popper hypothesis was put forth by Paul Ehrlich. — It states that ‘if an aeroplane equivalent to an ecosystem, has thousands of rivets equivalent to species. — If each passenger removes a rivet (= species) from the aeroplane, then it may not effect flight safety initially, but over a period of time, it may effect the plane dangerously weak. — Removal of rivets (= species) from a critical part (= a species performing major ecosystem functions) like wing will pose an immediate and serious threat to safety of the flight. — This analogy is comparable to the functioning of an ecosystem.
Biodiversity and its Conservation 169 3. Why is the sobriquet ‘The Evil Quartet’ used in context of biodiversity? Name the members of this quartet. Why do we grieve for the genes when a species is lost? Ans. The ‘Evil Quartet’ is used as a sobriquet to refer to the cause of loss of biodiversity which include: (i) Habitat loss and fragmentation When large habitats are broken up into smaller fragments due to various human activities, the animals requiring large territories (some mammals and bird species) are badly affected and their population decline. (ii) Over-exploitation When need of a resource become greed, it causes depletion of the resource, e.g. over-exploitation of passenger pigeon led to its extinction. (iii) Alien species invasion Intentional or non-intentional introduction of a species of a nearby area may disturb the harmony of existing species, e.g., water hyacinth (Eichhornia) an alien species has posed a big threat to our native species. (iv) Co-extinction Extinction of one species invariably leads to extinction of another when they are associated with each other in an obligatory way, e.g., when a host species become extinct, the obligate parasites dependent on it also die. We grieve for the loss of genes, because a gene once lost is lost forever, e.g. a wild variety having resistant gene against a pathogen, when become extinct deprive us from its benefits. 4. Who proposed the Rivet-Popper hypothesis of species diversity in the ecosystem? Explain the hypothesis. Ans. — Rivet-Popper hypothesis was put forth by Paul Ehrlich. — It states that ‘if an aeroplane equivalent to an ecosystem, has thousands of rivets equivalent to species. — If each passenger removes a rivet (= species) from the aeroplane, then it may not effect flight safety initially, but over a period of time, it may effect the plane dangerously weak. — Removal of rivets (= species) from a critical part (= a species performing major ecosystem functions) like wing will pose an immediate and serious threat to safety of the flight. — This analogy is comparable to the functioning of an ecosystem. 5. Why is the sobriquet ‘The Evil Quartet’ used in context of biodiversity? Name the members of this quartet. Why do we grieve for the genes when a species is lost? Ans. The ‘Evil Quartet’ is used as a sobriquet to refer to the cause of loss of biodiversity which include: (i) Habitat loss and fragmentation When large habitats are broken up into smaller fragments due to various human activities, the animals requiring large territories (some mammals and bird species) are badly affected and their population decline.
170 Biology-XII (ii) Over-exploitation When need of a resource become greed, it causes depletion of the resource, e.g. over- exploitation of passenger pigeon led to its extinction. (iii) Alien species invasion Intentional or non-intentional introduction of a species of a nearby area may disturb the harmony of existing species, e.g., water hyacinth (Eichhornia) an alien species has posed a big threat to our native species. (iv) Co-extinction Extinction of one species invariably leads to extinction of another when they are associated with each other in an obligatory way, e.g., when a host species become extinct, the obligate parasites dependent on it also die. We grieve for the loss of genes, because a gene once lost is lost forever, e.g. a wild variety having resistant gene against a pathogen, when become extinct deprive us from its benefits. 6. Saurabh is studying in XIIth standard in a school. One day his biology teacher taught about the importance of biodiversity. He told that biological communities with more species, generally tend to be more stable than those with less species. (i) What does stability mean for a biological community? (ii) Explain, how did David Tilman’s experiments using outdoor plots supported teacher’s view? Ans. (i) — A stable community should not show too much variation in productivity from year to year. — I t must be either resistant or resilient to occasional disturbances (natural or man-made) and — It must also be resistant to invasions by alien species. (ii) Tilman found that plots with more species showed less year to year variation in total biomass. He also showed that increased diversity contributed to higher productivity. 7. The overexploitation of natural resources by humans in the name development, resulting loss of biodiversity at all the levels of biological organisation. (i) Will it be realistic and economically feasible to conserve all biological wealth? Justify your view. (ii) Ecologists identified certain ‘biodiversity hot spot’ regions. What are these regions? (iii) How many such regions are there in the world? Give the names of ‘biodiversity hotspot regions of India. (iv) H ow does protection of such regions reduce the ongoing loss of biodiversity? Ans. (i) F aced with the conflict between development and conservation, it will not be realistic and economically feasible to conserve all the biological wealth, as it will require lot of money and man power.
Biodiversity and its Conservation 171 (ii) Hot spots of biodiversity are the regions with very high levels of species richness and high degree of endemism (i.e., species confined to that region and not found anywhere else). (iii) There are 34 biodiversity hot spots in the world. Three of these biodiversity hot spots—(i) Western Ghats and Sri Lanka (ii) Indo-Burma and (iii) Himalaya are in India. (iv) All the biodiversity, hot spots put together cover less than 2 percent of the earth’s land area, the number of species they collectively harbour is extremely high. Therefore protection of these areas could reduce the ongoing mass extinctions by almost 30 percent. Case Study Based MCQs I. The genetic variation existing within a species is called genetic diversity. The variation may be in alleles (different variants of a gene), total genes or chromosome structures. The number of genes present in a species differs from those present in another species. For instance, the number of genes is about 450–700 in Mycoplasma, 4,000 in Escherichia coli, 13,000 in Drosophila melanogaster, 32,000–50,000 in Oryza sativa and 35,000–45,000 in Homo sapiens. Genetic diversity within a species often increases with environmental variability. Rauwolfia vomitoria a medicinal plant growing in different Himalayan ranges, shows differences in the potency and concentration of active chemical called reserpine due to genetic diversity. Genetic diversity helps in speciation or evolution of new species. 1. Which one of the following shows maximum genetic diversity in India ? (a) Mango (b) Groundnut (c) Rice (d) Maize Ans. (c) 2. Maximum species diversity is seen in latitudinal range of: (a) 23.5º N to 66.5º N (b) 23.5º N to 23.5º S (c) 23.5º S to 66.5º N (d) 66.5º N to 90º N. Ans. (b) 3. Genetic diversity refers to (a) the differences in alleles within species (b) differences in entire alleles (c) differences in chromosomal structures (d) all of these Ans. (d) 4. Diversity of organism over total landscape or geographical area is termed as (a) Alpha diversity (b) Beta diversity (c) Gamma diversity (d) All of these Ans. (c)
172 Biology-XII 5. The important levels of biodiversity are (a) genetic biodiversity (b) species biodiversity (c) ecological biodiversity (d) All of these Ans. (d) II. Biodiversity is not uniform on the earth. It varies with change in latitude or altitude. For many groups of animals or plants, there is latitudinal gradient in diversity. In general, species diversity decreases as we move away from the equator towards the poles. It is because the tropical region has favourable conditions for the growth throughout the year, whereas temperate and arctic regions have severe climate with short growing period for plants. With very few exceptions, tropics (latitudinal range of 23.5°N to 23.5°S) harbour more species than temperate and polar areas. Columbia located near equator has about 1400 species of birds, New York (41°N) has 105 species and Greenland (71°N) has only 56 species. India having much of its land in the tropical latitudes, has more than 1,200 species of birds. 1. Hot spots of biodiversity are area with (a) little biodiversity (b) maximum biodiversity (c) maximum conservation (d) both (a) and (c) Ans. (b) 2. Which pair of geographical area shows maximum diversity in our country? (a) Eastern Ghats and West Bengal (b) Eastern Himalayas and Western Ghat (c) Sunderban and Rann of Kutch (d) Kerala and Punjab Ans. (b) 3. Which one of the following areas in India, is a hot spot of biodiversity? (a) Eastern Ghats (b) Gangetic Plain (c) Sunderbans (d) Western Ghats Ans. (d) 4. Select the correct statement about biodiversity. (a) The desert areas of Rajasthan and Gujarat have a very high level of desert animal species as well as numerous rare animals. (b) Large scale planting of Bt cotton has no adverse effect on biodiversity. (c) Western Ghats have a very degree of species richness and endemism. (d) Conservation of biodiversity is just a fad pursued by the developed countries. Ans. (c) 5. An ecologist uses the term biodiversity for the variety of species of (a) All living plants (b) All living animals (c) Both (a) and (b) above (d) (a), (b) above and microbes also living in their natural habitats. Ans. (d)
ISBN: 978-93-93268-20-4 789393 268204 T12-6735-249-COMP.CBSE QB BIO T-II XII
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