202110204-APEX-STUDENT-WORKBOOK-BIOLOGY-G09-PART2

Q2. What is pH? What is its range? What are the negative impacts if the pH of soil is too low or too high? [Refer to TB page 167 Q10] A. 1. The term pH is used to indicate the level of acidity or alkalinity of the soil. 2. The range of pH values of a good soil lies from 5.5 to 7.5. Below pH 7 the soils are termed as acidic and above pH 7 they are alkaline. The pH of soil is important in determining the type of vegetation that will grow in the soil and the type of organisms that will live there. Also, the presence of organic matter in soil has a close relationship withpH of the soil. 3. Soil richer in organic matter is acidic in nature as a result of degradation of various substances producing various acids in soil. Availability of nutrients to plants is strongly tied to the pH in soil. 4. Negative impacts if pH of the soil is too high or too low: The availability of N, K, Ca, Mg and S tends to decrease with decreasing pH and in- crease with increasing pH. Both the conditions are not recommended for soil’s health. Q3. What is soil fertility? What are the sources of soil fertility? [Refer to TB page 167 Q11] A. Soil fertility can be described as organic matter content of the soil, with good living conditions for soil organisms and growing conditions for the roots, which are closely linked to soil structure, the availability of nutrients, the soil’s water holding capacity and its biological activity. Sources of soil fertility: 1. Physical sources: i. Well developed structure and texture of the soil ii. Adequate porosity of air and water exchange capacity of the soil iii. Ample water retention (water holding) capacity 2. Biological and organic sources: i. Abundant biological activity ii. Availability of humus for plant nutrient intake iii. Nutrient cycling SESSION 1. INTRODUCTION AND SOIL - FORMATION, PROPERTIES A... 49

3.Chemical sources: i. Balance of chemicals and nutrients in the soil ii. Availability of macro nutrients iii. Optimal trace nutrients A major part of the soil microbial biomass is composed of fungi. Important soil fungi, the Mycorrhizae, grow in symbiosis with about 90% of all plant roots. Q4. Name 5 or 10 living things that live in soil. What do these things do to affect the soil? [Refer to TB page 167 Q18] A. Living things that live in the soil are: Viruses, bacteria, fungi, algae, protozoa, earth- worms, gophers, ground squirrels, worms, plant roots, snakes, moles, insects etc. i. All these organisms feed on plant residues in the soil and help in aeration and percolation of water. ii. Soil microbes also exert much influence in controlling the quantities and forms of various chemical elements found in soil. Most notable are the cycles for carbon, nitrogen, sulphur and phosphorus, all of which are elements important for soil fertility. iii. Soil microbes convert organic forms of elements to their inorganic forms and lib- erate carbon dioxide, ammonia, sulphate, phosphate and inorganic forms of other elements. This process is known as ‘mineralization’. This forms the basis of nutri- ent cycles in major ecosystems of the world. iv. Besides their role in controlling the rates of production of inorganic forms from var- ious organic forms, soil microbes, particularly, soil bacteria also control the forms of ions in which these nutrients occurs. Q5. What is organic matter? Why is it important to plants? [Refer to TB page 167 Q12] A. 1. Organic matter is the organic component of soil which includes the residues of dead plants, animals and organisms. 2. It consists of nutrients necessary for plant growth such as nitrogen, phosphorus and potassium. Soils which contain 30% or more organic matter are considered organic soils and all other soils are called mineral soils. SESSION 1. INTRODUCTION AND SOIL - FORMATION, PROPERTIES A... 50

Importance of organic matter to plants: 1. Organic matter in soil improves water infiltration, decreases evaporation and increases the water holding capacity. 2. When there is organic matter in the soil there will be numerous organisms present in it which help in creating conditions ideal for cultivation Q6. What are the factors affecting organic matter levels in soil? How this level of organic matter can be increased? [Refer to TB page 167 Q13] A. 1. Soil temperature, moisture, soil composition are the factors affecting organic matter levels in the soil. 2. It can be increased by: a. Crop rotation: Crop rotations of cereals with legumes results in higher soil organic manure b. Combining compost, plant or animal materials/waste, or green manure with soil will increase the amount of Organic matter in the soil. Q7. Rank the negative impact practices in your area in the order in which you think they should be eliminated. [Refer to TB page 167 Q7] A. i. Over usage of pesticides and insecticides as they affect the soil fertility. ii. Practices that lead to soil erosion. iii. Dumping of chemical wastes, radioactive materials, and disease causing agents as they have adverse effects on plant and animal health. iv. Taking care of disposing the non biodegradable substances. Q8. Rank the positive impact practices in order in which you think they should be used for the most benefit on your farm. [Refer to TB page 167 Q8] A. Following the 3R principle, i.e., Reduce, Recycle, Reuse. i. Reforesting, proper solid waste management, bioremediation. ii. Encouraging organic methods for cultivation. iii. Creating awareness among farmers regarding factors affecting soil fertility. SESSION 1. INTRODUCTION AND SOIL - FORMATION, PROPERTIES A... 51

1.5 Asking Questions and Making Hypothesis Q1. How would soil texture affect the nutrients in soil? What would be its impact on crop production? [Refer to TB page 167 Q16] A. 1. Soil texture has an important role in nutrient management because it influences nutrient retention. 2. For instance, finer textured soils tend to have greater ability to store soil nutrients and water. 3. Crop quality and the type of crops to be grown in a soil depend on the structure and texture of the soil. 4. Some crops grow well in fine texture soils whereas others grow in rough textured soil. Thus the texture has its impact on crop production. 1.6 Application to Daily Life, Concern to Bio Diversity Q1. Ravi said soil health is important. How can you support him? [Refer to TB page 167 Q23] A. Soil health plays a major role in many aspects of life: i. Healthy soil is fundamental to the quality of food it produces and to the health of those who eat the food produced from it. ii. When the soil components are present in appropriate percentage, the productivity is high. SESSION 1. INTRODUCTION AND SOIL - FORMATION, PROPERTIES A... 52

SESSION 2 SOIL AND LAND POLLUTION - CAUSES 2.1 Mind Map 2.2 Terminology i. Biodegradable waste –Biodegradable waste is a type of waste which can be brokendown into its base compounds by micro–organisms and other living things. ii. Non–biodegradable waste –Non–biodegradable waste is a type of waste that can not be broken down into its base compounds by micro–organisms, air, moisture or soil in a reasonable amount of time. iii. Soil erosion –Soil erosion is a naturally occurring process that affects all landforms. iv. Biomagnification –Biomagnification refers to the accumulation of toxins through the trophic levels of a food chain. v. Fertilizers –A fertilizer is any material of natural or synthetic origin that is applied to soils or to plant tissues to supply one or more plant nutrients essential to the growth of plants. vi. Solid wastes –The term solid waste means materials such as household garbage (includes recycling), food wastes, yard wastes, and demolition or construction debris. vii. Urbanization –The gradual increase in the proportion of people living in urban areas. viii. Deforestation –Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a non–forest use. SESSION 2. SOIL AND LAND POLLUTION - CAUSES 53

2.3 Key Concepts i. Addition of unwanted substances that adversely affect the quality of the soil is termed as soil pollution. ii. Bio degradable wastes are those that can be decomposed by bacterial or biological decomposition. iii. Non bio degradable wastes are those that cannot be decomposed by bacterial or biological decomposition. iv. Addition of fertilizers, pesticides, herbicides, weedicides, deforestation, soil erosion, dumping solid wastes are causes of land pollution. v. Urbanization has caused pollution to surface and underground soil. Clogging of drains obstructs movement of water and causes a foul smell. vi. Plastic is a nightmare and is a curse that appears to be a boon to mankind because it makes life simple but takes several years to decompose. 2.4 Conceptual Understanding Q1. Define soil pollution. [Refer to TB page 167 Q1] A. Soil or land pollution can be defined as addition of substances which adversely affect the quality of soil and its fertility. Q2. Chemical fertilizers are useful to crops. In which way they cause environmental pollu- tion? [Refer to TB page 167 Q3] A. i. Soil nutrients are important for plant growth and development. Plants obtain car- bon, hydrogen and oxygen from air and water, but other necessary nutrients like nitrogen, phosphorus,potassium, calcium, magnesium, sulphur must be obtained from the soil. ii. Farmers generally use fertilizers to overcome soil deficiencies. Fertilizers contam- inate the soil with impurities, which come from the raw materials used for their manufacture. Mixed fertilizers contain ammonium nitrate (NH4 NO3), phosphorus as P2 O5 and potassium as K2 O. For instance, As, Pb and Cd present in traces in rock phosphate mineral get transferred to super phosphate fertilizer. iii. Since the metals are not degradable, their accumulation in the soil is due to exces- sive use of phosphate fertilizers which becomes an indestructible poison for crops. The over use of NPK fertilizers reduce the quantity of vegetables and crops grown insoil over the years. SESSION 2. SOIL AND LAND POLLUTION - CAUSES 54

iv. Excess potassium content in soil decreases Vitamin C and carotene content in vegetable and fruits. The vegetables and fruits grown in over fertilized soil are more prone to attacks by insects and disease. 2.5 Communication Through Drawing and Model Making Q1. Prepare a flow chart to describe soil pollution, causes and methods of control. [Refer to TB page 167 Q19] A. 2.6 Appreciation and Aesthetic Sense, Values Q1. Why plastic bags are considered a big environmental nuisance? [Refer to TB page 167 Q21] A. Plastic with its exclusive qualities of being light yet strong and economical has invaded every aspect of our day–to–day life. SESSION 2. SOIL AND LAND POLLUTION - CAUSES 55

i. Conventional plastics have been associated with reproductive problems in both wildlife and humans. ii. Dioxin, a highly carcinogenic and toxic by–product of the manufacturing process of plastics mixes with the air and is passed on through breast milk to the nursing infant. iii. Burning of plastics, especially PVC releases dioxin and also furan into the atmo- sphere. iv. Careless disposal of plastic bags chokes drains, blocks the porosity of the soil and causes problems in groundwater recharge. v. Plastic disturbs the soil microbe activity, and once ingested, can kill animals. vi. Plastic bags can also contaminate foodstuffs due to leaching of toxic dyes and transfer of pathogens. Thus, conventional plastics, right from their manufacture to their disposal are a major problem to the environment. Though only a small percentage lies strewn, it is this portion that is of concern it causes extensive damage to the environment 2.7 Application to Daily Life, Concern to Bio Diversity Q1. What soil problems do you find in your area? Prepare a list of those problems and suggest a method for each of them to control those problems. [Refer to TB page 167 Q22] A. Problems: 1. Dumping of waste materials at random places. 2. Disposal of industrial and chemical wastes at places near to residential areas. 3. Soil erosion 4. Lack of awareness about importance of soil fertility. Control measures : 1. Adopt 3R’s–Reduce, reuse and recycle. 2. Reuse glass containers, plastic bags, paper bags. It reduces solid waste pollution. 3. Recycle plastic, paper and glass it helps in the conservation of resources. SESSION 2. SOIL AND LAND POLLUTION - CAUSES 56

SESSION 3 SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND CONSERVATION 3.1 Mind Map 3.2 Terminology i. Bioremediation – Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminated site. ii. Recycling – Recycling is a process to convert waste materials into reusable material to prevent waste of potentially useful materials. iii. Reforesting – Reforesting is the process of replacing plants in an area where they have been cut down or destroyed. iv. Solid waste management –Solid waste management is one of the major challenges faced by many countries around the globe. v. Soil conservation – Soil conservation is the prevention of soil from erosion or reduced fertility caused by overuse, acidification, salinization or other chemical soil contamination. vi. Contour ploughing – Contour ploughing or contour farming is the farming practice of ploughing and/or planting across a slope following its elevation contour lines. SESSION 3. SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND ... 57

3.3 Key Concepts i. Following 3R policy (reduce, reuse and recycle) may decrease soil pollution to some extent. ii. Pyrolysis is the combustion in the absence of oxygen. iii. The Best way to decompose human and cattle waste is to produce gobar gas or biogas. iv. Bio-remediation is the means to use biological remedies to clean up the earth and usage of plants to clean up is called phytoremediation. v. Natural disasters like Earthquakes, landslides, hurricanes and floods cause land pol- lution. 3.4 Conceptual Understanding Q1. Describe an environmental friendly method to profitably dispose of human waste and cattle waste. [Refer to TB page 167 Q2] A. i. Environmental friendly method to dispose human and cattle waste is generation of biogas or gobar gas. ii. Anaerobic/aerobic decomposition of biodegradable municipal and domestic waste is also being done and gives organic manure. iii. Cow dung which releases methane into the atmosphere, should be processed further in ‘gobar gas plants’ to produce ‘gobar gas’ and good manure. Q2. What steps can be taken to reduce pollution due to particulate matter from industries? [Refer to TB page 167 Q4] A. Particulate matter (PM) refers to small solid or liquid particles floating in the air. These particles can be made up of different substances, including carbon, sulphur, nitrogen and metal compounds. Generally, smaller particles are thought to be more harmful to health than larger particles because they can move deeper into the respiratory tract, including the lungs. For this reason, fine particles are linked to more serious health effects than larger particles. To reduce pollution due to particulate matter, the following steps may be taken: i. Consider alternative fuels such as natural gas or bio–gas instead of coal. ii. Consider fuel–cleaning options such as coal washing, which can reduce ash con- tent by up to 40%. SESSION 3. SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND ... 58

iii. Consider alternative production processes and technologies, such as fluidized bed combustion, that result in reduced PM emissions. iv. Select optimal particulate removal devices. v. Industries must have emission equipment to reduce particulate pollution vi. Renewable energy sources can be used instead of burning fossil fuels which re- lease particulate matter. Q3. What farm practices impact soil? Do they impact soil in a positive or a negative way? [Refer to TB page 167 Q6] A. The farm practices that impact soil in a positive way are: No–till farming: : i. When soil is prepared for farming by ploughing it, the process is known as tilling. ii. No–till farming is a way of growing crops without disturbing it through tillage. The process of tilling is beneficial in mixing fertilizers in the soil, shaping it into rows and preparing a surface for sowing. iii. But the tilling activity can lead to compaction of soil, loss of organic matter in soil and the death of the organisms in soil. iv. No–till farming is a way to prevent the soil from being affected by these adversities. Contour ploughing: i. This practice of farming across the slopes takes into account the slope gradient and the & elevation of soil across the slope. ii. It is the method of ploughing across the contour lines of a slope. iii. This method helps in slowing the water runoff and prevents the soil from being washed away along the slope. iv. Contour ploughing also helps in the percolation of water into the soil. Crop rotation: SESSION 3. SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND ... 59

i. Some pathogens tend to build up in soil if the same crops are cultivated consecu- tively. ii. Continuous cultivation of the same crop also leads to an imbalance in the fertility demands of the soil. To prevent these adverse effects from taking place, crop rotation is practised. iii. It is a method of growing a series of dissimilar crops in an area sequentially, Crop rotation also helps in the improvement of soil structure and fertility. Terracing: i. Terracing is one of the very good methods of soil conservation. ii. A terrace is a leveled section of a hilly cultivated area. Owing to its unique struc- ture, it prevents the rapid surface runoff of water. iii. Terracing gives the landmass a stepped appearance thus slowing the easy wash- ing down of the soil. Dry stonewalling is a method used to create terraces in which stone structures are created without using mortar for binding. Q4. What is bioremediation? How does it help in controlling soil pollution? [Refer to TB page 167 Q15] A. i. Bioremediation means to use a biological remedy to abate or clean up contam- ination. This makes it different from remedies where contaminated soil or water is removed for chemical treatment or decontamination, incineration, or burial in a landfill. ii. Microbes are often used to remedy environmental problems found in soil, water, and sediments. Plants have also been used to assist bioremediation processes. This is called phytoremediation. iii. Biological processes have been used for some inorganic materials, like metals, to lower radioactivity and to remediate organic contaminants. iv. With metal contamination the usual challenge is to accumulate the metal into har- vestable plant parts, which must then be disposed off in a hazardous waste landfill before or after incineration to reduce the plant to ash. Two exceptions are mercury and selenium, which can be released as volatile elements directly from plants to atmosphere. SESSION 3. SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND ... 60

Q5. What is a medical waste? Why it is called hazardous waste? What is a safe way to dispose of medical waste? [Refer to TB page 167 Q5] A. Medical waste: Medical waste is solid waste generated during diagnosing, treating or immunizing people or animals. Waste generated by health care activities includes a broad range of materials, from used needles and syringes to soiled dressings, body parts, diagnostic samples, blood, chemicals, pharmaceuticals, medical devices and ra- dioactive materials. Hazardous Solid Waste: Industrial and hospital waste is considered to be hazardous waste as they contain toxic substances. Safe ways to dispose of medical wastes: i. Collection, transfer and transport to suitable sites, and safe disposal of wastes by methods which are environmentally compatible should be followed for the safe disposal of the hazardous medical waste. ii. Hazardous waste should be investigated and disposed of in methods such as deep well injection and more secure landfills. iii. Burying the wastes in locations situated away from residential areas is the simplest and most widely used technique of solid waste management. iv. Environmental and aesthetic considerations must be taken into consideration be- fore selecting the dumping sites. Q6. What is a solid waste? Explain the best practices for solid waste management. [Refer toTB page 167 Q14] A. The solid waste is the organic and inorganic wastes produced by various activities of the society and which have lost their value to the first user. The solid wastes which are accumulated on the soil will pose a great problem to us. Throwing the wastes in dump yards is not the solution to the problem. Proper methods should be adopted for management of solid waste disposal: i. Solid waste management involves activities including collection, transfer and trans- port to suitable sites, and safe disposal of wastes by methods which are environ- mentally compatible. ii. Industrial wastes can be treated physically, chemically and biologically until they are less hazardous. Acidic and alkaline wastes should be first neutralized; the SESSION 3. SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND ... 61

insoluble material if biodegradable should be allowed to degrade under controlled conditions before being disposed. iii. New areas for storage of hazardous waste should be investigated such as deep well injection and more secure landfills. Burying the waste in locations situated away from residential areas is the simplest and most widely used technique of solid waste management. iv. Environmental and aesthetic considerations must be taken into consideration be- fore selecting the dumping sites. v. Incineration of other wastes is expensive and leaves a huge residue and adds to air pollution. Pyrolysis is a process of combustion in absence of oxygen or the material is burnt under controlled atmosphere of oxygen. It is an alternative to incineration. The gas and liquid thus obtained can be used as fuels. Pyrolysis of carbonaceous wastes like firewood, coconut, palm waste, corn combs, cashew shell, rice husk paddy straw and saw dust, yields charcoal along with products like tar, methyl alcohol, acetic acid, acetone and a fuel gas. vi. Anaerobic/aerobic decomposition of biodegradable municipal and domestic waste is also being done which gives organic manure. Cow dung which releases methane into the atmosphere, should be processed further in ‘gobar gas plants’ to produce ‘gobar gas’ and good manure. 3.5 Asking Questions and Making Hypothesis Q1. Why soil conservation is important to us? What will happen if no preventive measures would be taken? [Refer to TB page 167 Q17] A. i. Soil conservation comprises of all the procedures and methods that involve pro- tecting the soil from natural as well as man–made destructions. ii. It is as important as any other form of conservation that attempts to safeguard the environment and improve the quality of life of all living beings. iii. Soil conservation helps to prevent soil degradation due to erosion, agricultural soil pollution etc iv. Conservation ensures that the soil maintains nutrients and microbial activity for future plant growth. v. If no preventive measures are taken to conserve the soil, the top soil may be lost due to soil erosion and the soil may lose its texture and fertility. It becomes unfit for growing crops. SESSION 3. SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND ... 62

3.6 Communication Through Drawing and Model Making Q1. Look at the following symbol. What does it mean? [Refer to TB page 167 Q20] A. i. The logo is the symbol for bioremediation. ii. Bioremediation is the use of biological agents such as microbes or plants to break down or neutralize “hazardous substances” or “contaminants” thereby removing dangerous chemicals in the environment. iii. The process of bioremediation is listed as one of the Environmental Protection Agency’s (EPA) innovative technologies. iv. It promotes use of organic substances in our day to day life so as to prevent pollu- tion. SESSION 3. SOIL AND LAND POLLUTION - EFFECTS, CONTROL AND ... 63

—— CCE Based Practice Questions —— AS1-Conceptual Understanding Column B Very Short Answer Type Questions a. Biological property 1. Match the following. [(Session 10.1)] Column A i. Soil above pH 7.8 ii. Mycorrhizae b. Productivity is high iii. Humus c. Enlarge root zone of the plant iv. Fungi d. Increase in alkalinity v. Appropriate percentage of components e. Major biomass of soil 2. Fill in the blanks. [Refer to Session 10.1 ] (i) The of the soil is to be balanced to determine the type of vegetation. (ii) Soil microbes convert forms of elements to forms. (iii) grow in symbiosis with about 90% of all plant roots. (iv) The process of conversion of organic forms into inorganic forms by microbes is called . (v) Organic matter in soil improves . 3. State true or false. [Refer to Session 10.3 ] (vi) Reducing of chemical fertilizers use reduces soil pollution. [ ] CHAPTER 10. SOIL POLLUTION 64

(vii) Reuse of material reduces soil pollution. [] (viii) Bioremediation means to use a biological remedy to abate or clean up contamination. [] (ix) No–till farming causes soil erosion. [] (x) Deforestation leads to soil pollution. [] 4. Match the following. Column B a. Biogas [(Session 10.3)] Column A i. Bioremediation ii. Phytoremediation b. Expensive Method iii. Incineration c. Clean up contamination iv. Crop rotation d. Improves soil fertility v. Gobar gas e. Plants 5. State true or false. [Refer to Session 10.2 ] (xi) Waste decomposed by bacteria is called biological decomposition. ] [ ] ] (xii) First widespread insecticide used was BHC. ] [ (xiii) Indiscriminate use of fertilizers causes soil fertilization. [ (xiv) Chemicals released by industrial wastes pollute underground soil. [ CHAPTER 10. SOIL POLLUTION 65

(xv) Foul smell is generated by dumping of wastes at a place. [] 6. Match the following. [(Session 10.2)] Column A Column B i. Biodegradable waste a. Soil Erosion ii. Nonbiodegradable waste b. Insecticide iii. DDT c. Excess use leads to soil pollution iv. NPK fertilizers d. Dung v. Deforestation e. Radioactive waste 7. Fill in the blanks. [Refer to Session 10.2 ] (xvi) Acid rain and dry deposition of pollutants on land surface also contribute to . (xvii) Soil are important for plant growth and development. (xviii) Farmers generally use to maintain soil nutrient level. (xix) Hospital waste is an example of waste. (xx) = (Total weight of wet waste materials) / (Number of persons in your family). Short Answer Type Questions 8. Answer the following questions in 3-4 sentences. (i) [(Session 10.1)] What is soil? (ii) [(Session 10.1)] Write a short note on pH of soil. CHAPTER 10. SOIL POLLUTION 66

9. Answer the following questions in 3-4 sentences. (i) [(Session 10.3)] Why recycling and recovery of materials is considered as one of the best methods to reduce soil pollution? (ii) [(Session 10.3)] Write a short note of pyrolysis. 10. Answer the following questions in 3-4 sentences. (i) [(Session 10.2)] What do you mean by decomposition? (ii) [(Session 10.2)] Distinguish between biodegradable waste and non–biodegradable waste with suitable examples. AS2-Asking questions and making hypothesis Short Answer Type Questions 11. Answer the following questions in 3-4 sentences. (i) [(Session 10.1)] Waheeda’s teacher taught about the components of soil in the class. Imagine you are Waheeda and write any two important points that you have learnt from the class. (ii) [(Session 10.1)] What questions would you like to ask your teacher about soil? 12. Answer the following questions in 3-4 sentences. (i) [(Session 10.3)] Now–a–days farmers are not interested in soil waste management. What does soil waste management involve? (ii) [(Session 10.3)] What are the effects of soil pollution in urban areas? AS6-Appreciation and aesthetic sense, Values Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 10.3)] How do you appreciate the Prime Minister’s Swach Bharath program? Is it helpful in controlling land pollution to some extent? CHAPTER 10. SOIL POLLUTION 67

AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 14. Answer the following questions in 3-4 sentences. (i) [(Session 10.1)] If you are given some organic forms of elements, how can you liberate carbon dioxide from them without using any chemicals? (ii) [(Session 10.1)] What may happen if we remove top soil from one acre of land? 15. Answer the following questions in 3-4 sentences. (i) [(Session 10.3)] Why we should not throw wastes wherever we want? (ii) [(Session 10.3)] What are the different methods which we can use for soil conserva- tion? Long Answer Type Questions 16. Answer the following questions in 6-8 sentences. (i) [(Session 10.3)] Release of polluted water near agricultural fields can affect fertility of soil and also the crop. Is it true? Explain. (ii) [(Session 10.3)] We often come across the words ‘biodegradable’ and ‘recyclable’. Do you think if we can reuse vegetable waste for electricity production? 17. Answer the following questions in 6-8 sentences. (i) [(Session 10.2)] ’ Hospital waste generated during diagnosis and treatment causes land pollution’. What are the steps to be taken here to rectify this? CHAPTER 10. SOIL POLLUTION 68

Objective Questions AS1-Conceptual Understanding 18. Choose the correct answer. (i) Which of the following resource has 45% mineral particles in it? (A) Air (B) Water (C) Soil (D)All of the above (ii) Land pollution occurs massively during (A) Earthquakes (B) Land slides (C) Floods (D)All of the above (iii) Which of the following is not a physical property of the soil? (A) Colour (B) Texture (C) pH (D) Porosity (iv) This method helps in the percolation of water into the soil. (A) No–till farming (B) Contour ploughing (C)Crop rotation (D)Planting trees (v) Major part of soil microbial biomass is composed of (A) Virus (B) Fungi (C) Algae (D) Protozoa (vi) Burning of fossil fuel adds (A) Only CO, SO2 gases in air (B) CO2 , SO2 , NO2 gases in air (C)Both A and B (D) None (vii) Life supporting zone of the earth is CHAPTER 10. SOIL POLLUTION 69

(A) Biosphere (B) Lithosphere (C) Hydrosphere (D) Atmosphere (viii) The gas present in gobar gas is (A) Ethane (B) Methane (C) Propane (D) Methylene (ix) The layer of the soil which is the foundation for life on the earth is (A) Middle layer (B) Bottom layer (C)Top layer (D)None of the above (x) Which of the following terms is used for combustion in the absence of air? (A) Reduction (B) Deoxygenation (C) Combustion (D) Pyrolysis (xi) Which of the following constitute the highest percentage in the composition of soil? (A) Air (B) Water (C)Mineral Particles (D)Organic matter (xii) Organic soil is the one which consists of % of organic matter. (A) 30 or more (B) less than 30 (C)10 or more (D)less than 10 (xiii) The best range of pH for a good soil is: (A) Below pH 7 (B) Above pH 7 (C)Between pH 5.5 –7.5 (D)Both A and B (xiv) Mycorrhiza is the symbiotic association of which of the following? CHAPTER 10. SOIL POLLUTION 70

(A) Soil bacteria and plant roots (B) Soil fungi and plant roots (C)Soil bacteria and soil fungi (D)Both A and B (xv) e–waste is an example of: (A) Biodegradable waste (B) Non–biodegradable waste (C)Infectious solid waste (D)Re–usable waste (xvi) What is meant by Pyrolysis? (A) Combustion in the absence of oxygen (B) Combustion in the presence of oxygen (C)Using plants for cleaning contamination (D)Both A and C (xvii) Earthworms increase soil fertility by: (A) Increasing soil porosity (B) Enhancing availability of macronutrients in soil (C)Killing harmful insects and microbes in soil (D)Both A and B (xviii) The three R’s for control of soil pollution stands for: (A) Reduce, Reuse and Recycle (B) Return, Reuse and Recover (C)Reuse, Recycle and Reprocess (D)Reuse, Recycle and Reclaim (xix) Which of the following chemicals present in polluted underground water is not dangerous for human life? (A) Cadmium (B) Arsenic (C) Lead (D) Potassium CHAPTER 10. SOIL POLLUTION 71

(xx) Which of the following waste is biodegradable? (A) DDT (B) Aluminium cans (C) Hay (D)Plastic materials CHAPTER 10. SOIL POLLUTION 72

11. BIOGEOCHEMICAL CYCLES SESSION 1 INTRODUCTION AND THE WATER CYCLE 1.1 Mind Map SESSION 1. INTRODUCTION AND THE WATER CYCLE 73

1.2 Terminology i. Water cycle/hydrologic cycle – The whole process in which water evaporates and comes back to the surface of the earth as rain and other forms of precipitation includ- ing its flow from land into the sea/oceans via several routes like rivers, ground water channels etc. is known as the water–cycle. ii. Ground water – Groundwater is the water present beneath earth’s surface in soil pore spaces and in the fractures of rock formations. iii. Condensation – Condensation is the process of change of water from its gaseous form (water vapor) into liquid water. iv. Acid rain –Acid rain describes any form of precipitation with high levels of nitric and sulfuric acids. 1.3 Key Concepts i. Living things within an ecosystem interact with each other and also with their non–living environment to form an ecological unit. ii. Resources in the ecosystem have to be regenerated. iii. The cycles that involve the flow of nutrients (elements essential for the living cell) from the environment to organisms and back through certain pathways are known asbiogeochemical cycles. SESSION 1. INTRODUCTION AND THE WATER CYCLE 74

iv. There is a constant interaction between biotic and abiotic components in the ecosys- tem. These interactions consist of transfer of matter and energy between the different components of the biosphere. v. Water is constantly recycled in a process known as the hydrological cycle or water cycle. 97% of all the water on the earth is in the oceans, and so only about 3% is fresh water. About 2% of this fresh water is permanently frozen in glaciers and in the polar ice caps. vi. There is only about 1% is available fresh water. About 1/4 of this 1% of it is present as groundwater. Only about 0.009% of water on earth is in the rivers and lakes. vii. Human body has about 70% of water. viii. The whole process in which water evaporates and comes back to the surface of the earth as rain and other forms of precipitation including its flow from land into the sea/oceans via several routes like rivers, ground water channels etc. is known as the water–cycle. ix. Water provides hydrogen and oxygen that form integral part of basic organic com- pounds of life. x. Dissolution of some harmful substances like gases like SO2 and oxides of nitrogen in rain water leads to acid rain. 1.4 Conceptual Understanding Q1. What is the importance of different biogeochemical cycles in the nature? [Refer to TB page 182 Q1] A. 1. Biogeochemical pathways determine the path of transfer of matter on earth. The name itself it includes biological, geological and chemical or physiochemical pathways. This means the reservoir or pool of nutrients on earth may contain some chemicals of biological origin while others may be purely inorganic in nature, some may also be geochemical (obtained from rocks and soil) in origin. 2. A constant interaction between the biotic and abiotic components of the biosphere makes it a dynamic and a stable system. 3. These interactions consist of transfer of matter and energy between the different components of the biosphere. 4. Biogeochemical cycles are important to understand how nature is maintaining itself and the impacts of human activities on this self–contained ecological unit, e.g.water cycle, nitrogen cycle etc. SESSION 1. INTRODUCTION AND THE WATER CYCLE 75

Q2. Why could we say that biogeochemical cycles are in “balance”? [Refer to TB page 182 Q3] A. We can certainly say that biogeochemical cycles are in “balance” as they satisfy the following: i. The biogeochemical cycles are the key to the movement of nutrients through an ecosystem. ii. Living things need these nutrients to survive and grow, and when they die, the materials are recycled through the system. iii. Nitrogen is used in nucleic acids, to form proteins in all living organisms. iv. Carbon is the core element for almost all living things. v. Biogeochemical cycles link living organisms with other living organisms, living organisms with the non–living organisms and non–living organisms with other non–living organisms. Biogeochemical cycles regulate the flow of substances. vi. Matter is continually recycled among living and abiotic elements on earth. vii. Biogeochemical cycles facilitate the transfer of matter from one form to another and from one location to another on earth. viii. Additionally, biogeochemical cycles are sometimes called nutrient cycles because they involve the transfer of compounds that provide nutritional support to living organisms. 1.5 Asking Questions and Making Hypothesis Q1. If all the vegetation in the pond died, what effects would it have on the animals? Why? [Refer to TB page 182 Q4] A. i. All the organisms on earth are interdependent. ii. They form a part of one or more food chains and in turn are present in the food web. iii. If all the vegetation in the pond died, the life in the pond would come to a halt. iv. Carnivores in a pond feed on herbivores, herbivores feed on plants, and plants in turn depend on sunlight, water and carbon dioxide. v. So, when plants (vegetation) die, all life would slowly die of starvation due to lack of food. SESSION 1. INTRODUCTION AND THE WATER CYCLE 76

1.6 Information Skills and Projects Q1. Go to a nearby pond. Observe organisms living in the pond and bio degradable sub- stance mixing in water. How do they affect those organisms? Write your observation. [Refer to TB page 182 Q6] A. i. The term biodegradable is used to describe materials that decompose through the actions of bacteria, fungi, and other living organisms. ii. Bio degradable substances present in the ponds does not adversely affect the organisms living in the ponds. iii. Bio degradable substances in the pond are broken down in to simpler substances that do not harm the organisms surviving in the pond. 1.7 Application to Daily Life, Concern to Bio Diversity Q1. How do human activities cause an imbalance in biogeochemical cycles? [Refer to TB page 182 Q11] A. 1. Human activities cause an imbalance in biogeochemical cycles. For e.g., humans have altered the biological carbon cycle, increasing atmospheric CO2 levels through forest clearing and land use. 2. Trees store large amounts of carbon; when they die and decompose, much of this stored carbon is released as CO2 . 3. However, when humans clear large expanses of forest, primarily through the use of fire, the levels of atmospheric carbon are affected in two ways. 4. First, during combustion, stored carbon is released directly into the air as CO2 , and second, the clearing of land takes away a key mechanism for removing excess carbon dioxide from the atmosphere (via photosynthesis). 5. Since carbon dioxide is a primary greenhouse gas, the increase in atmospheric CO2 due to human activities has resulted in an enhanced greenhouse effect resulting in higher global temperatures. SESSION 1. INTRODUCTION AND THE WATER CYCLE 77

Q2. List three ways we, as humans, have affected the water cycle. [Refer to TB page 182 Q12] A. i. By cutting down trees;which cools the atmosphere to bring rains into the water cycle. ii. By releasing pollutants and harmful chemicals into the nearby rivers and oceans; ocean water dissolves the chemicals and evaporates. This mixes with gases when coming down as rain and thus forms acid rains. iii. By using chemical fertilizers which get mixed up with water and seep into the ground and pollutes the underground water, which is a part of water cycle. SESSION 1. INTRODUCTION AND THE WATER CYCLE 78

SESSION 2 NITROGEN CYCLE 2.1 Mind Map 2.2 Terminology i. Nitrogen cycle – Nitrogen cycle is a complex biological cycle in which nitrogen is con- verted from its inert atmospheric molecular form into a form that is useful in biological process. ii. Nitrogen fixation –Atmospheric nitrogen is converted into a form that can be used by plants is the process called nitrogen fixation. iii. Nitrification –Nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrates. iv. Assimilation – Assimilation is the process in which nitrates or ammonium ions are taken up from the soil by plants and then used in the formation of plants proteins and animals eat these plants, animal proteins are synthesized. SESSION 2. NITROGEN CYCLE 79

2.3 Key Concepts i. The nitrogen cycle is a complex biogeochemical cycle in which nitrogen is converted from its inert atmospheric molecular form ( N2 ) into a form that is useful in biological processes. ii. Atmospheric nitrogen is converted into a form that can be used by plants is the pro- cess called nitrogen fixation. iii. Rhizobium and Nitrosomonas are biological forms able to fix atmospheric nitrogen. iv. Production of ammonia ( NH3 ) from nitrates and other nitrogenous compounds called as ammonification. v. Nitrate ( NO3 ) is converted back to gaseous nitrogen ( N2 ) in the process of denitrification. 2.4 Communication Through Drawing and Model Making Q1. Describe interdependence of biotic and abiotic components by taking nitrogen cycle as an example. [Refer to TB page 182 Q7] A. i. A constant interaction between the biotic and abiotic components of the biosphere makes it a dynamic, but a stable system. These interactions consist of transfer of matter and energy between the different components of the biosphere. ii. E.g. Nitrogen is the most abundant element in the atmosphere and a building block of proteins and nucleic acids. The nitrogen cycle is a complex biogeochemical cycle in which nitrogen is converted from its inert atmospheric molecular form ( N 2 ) into a form that is useful in biological processes. iii. The element nitrogen is constantly moving in a giant circle from the air, through the soil, into the bodies of plants and animals, and eventually back to the air by the process of nitrogen cycle. iv. The atmospheric nitrogen is thus converted into certain compounds that plants may take up from the soil by some biochemical (caused by certain bacteria like Rhizobium, Nitrosomonas etc.) and physico–chemical (caused by lightning) pro- cesses. Animals get the required amount of nitrogen from plants either directly (herbivores) or indirectly (carnivores). SESSION 2. NITROGEN CYCLE 80

The nitrogen cycle is as follows: 1. Nitrogen fixation: Most atmospheric nitrogen is ‘fixed’ through biological processes. Rhizobium and Nitrosomonas convert atmospheric nitrogen into the organic nitrogen for their own cells. As they die, this nitrogen, now present in the soil as compounds be- come available to plants. In leguminous plants like pea, beans etc. there is a symbiotic relationship of the nitrogen fixing bacteria with the plant. Nitrogen can also be fixed as nitrates by lightening. This reaches soil and water through precipitation that follows. Nitrates are taken up by plants to form proteins and nucleic acids. 2. Nitrification: Nitrates can also be converted to ammonia by the nitrifying bacteria in the soil. The nitrifying bacteria may then use this ammonia to synthesize compounds for their own cell and it is eventually converted to proteins, nucleic acids, nitrites and nitrates. Nitrites are produced mainly by Nitrosomonas, and nitrates by Nitrobacters. These are capable of utilizing nitrites and converting them to nitrates. Death of the microorganisms adds the nitrogenous compounds to the soil. Plants take up nitrates as well as ammonium ions from the soil to convert them to proteins and nucleic acids. 3. Assimilation: Nitrogen compounds mainly as nitrates or ammonium ions ( NH4- ) are taken up from soils by plants which are then used in the formation of plant proteins and as animals eat these plants, animal proteins are also synthesized. 4. Ammonification: Production of ammonia (NH3 ) from nitrates and other nitrogenous compounds is called as ammonification. Ammonification also occurs when plants and animals die, or when animals emit wastes, the nitrogen in the organic matter enters the soil and water bodies where it is broken down by other microorganisms, known as decomposers. This decomposition produces ammonia which is then available for other biological processes. 5. Denitrification: Nitrogen makes its way back into the atmosphere through a process called denitrification, in which solid nitrate ( NO3 ) is converted back to gaseous nitrogen. SESSION 2. NITROGEN CYCLE 81

SESSION 3 THE CARBON CYCLE 3.1 Mind Map 3.2 Terminology i. Carbon cycle –It is the process in which carbon travels from the atmosphere into organisms and the earth and then back into the atmosphere. ii. Greenhouse Effect – The warming of the earth’s atmosphere and surface by the at- mospheric greenhouse gases such as carbon dioxide, methane and water vapours is called greenhouse effect. SESSION 3. THE CARBON CYCLE 82

iii. Global warming –Phenomenon of increase in the earth’s temperature is called global warming. iv. Combustion –Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. 3.3 Key Concepts i. Carbon occurs in the elemental form as soot, diamond and graphite. In the com- bined state, it is found as the gases –carbon dioxide and carbon monoxide in the atmosphere ii. Carbon dioxide ( CO2 ) makes up about 0.04% by volume of air. Animals and humans return carbon to the atmosphere as CO2 through respiration. Plants accept CO2 in the process of photosynthesis. iii. Phenomenon of increase in the earth’s temperature is called global warming. iv. Release of carbon dioxide and other gases into the atmosphere has depleted the ozone layer and that leads to greenhouse effect. 3.4 Experimentation and Field Investigation Q1. Write an experiment to prove Green house effect on temperature. [Refer to TB page 182 Q5] A. Aim : Test the effect of a greenhouse on temperature. Materials Required : Plastic bottle, nail, 2 thermometers, notebook and pencil. Procedure : i. Make a hole on top of the plastic bottle with a nail. ii. Insert the first thermometer into the hole. iii. Place the second thermometer next to the bottle. Make sure the same amount of sunlight reaches both the thermometers. iv. Note the temperature values for both the thermometers after 10 minutes. v. Record the values in a notebook. vi. Take the temperature record again after 10 minutes and repeat it for 2–3 times. Observation : The temperature values for both the thermometers are different. Conclusion : Greenhouse gases increase the atmospheric temperature. SESSION 3. THE CARBON CYCLE 83

3.5 Appreciation and Aesthetic Sense, Values Q1. Burning of fossil fuels a concern for scientists and environmentalists.Why? [Refer to TB page 182 Q9] A. i. Coal, petrol and natural gas are called fossil fuels. They are so called as they are formed due to the decomposition of dead plants and animals from several thousands of years. They are drilled from the layers of earth and made useful. They are non–renewable resources. ii. Human beings tap into the geological carbon cycle by extracting oil and coal, which are both hydrocarbons (formed of carbon and hydrogen),used in automobiles and power plants. The by-products of combustion of these hydrocarbons are CO2 and CO gases. Carbon dioxide levels in the atmosphere have increased measur- ably, mostly as a result of human use of fossil fuels. iii. Burning any of these fossil fuels would release carbon dioxide. Carbon dioxide is a greenhouse gas. It is responsible for depletion of ozone layer and thus leads to global warming. Global warming is an alarming factor as it can cause droughts, famines or floods. This would create a great threat to life of organisms. Hence scientists and environmentalists are concerned about burning fossil fuels. 3.6 Application to Daily Life, Concern to Bio Diversity Q1. What role does carbon dioxide play in plant life processes? [Refer to TB page 182 Q10] A. Carbon is incorporated into life through various processes. It plays a major role in plant life processes as it helps in photosynthesis. Photosynthesis is a life process in which carbohydrates are produced by plants with the help of water, sunlight and carbon diox- ide. i. Photosynthesis : The first step in the biological carbon cycle is the conversion of inorganic atmospheric carbon into a biological form. ii. This ‘fixing’ of carbon in biological form takes place within plants and other organ- isms known as producers a process called photosynthesis, by which energy from sunlight is converted into chemical form. SESSION 3. THE CARBON CYCLE 84

iii. In photosynthesis, light energy helps to combine carbon dioxide and water to cre- ate the simplest of sugars, the carbohydrate molecules known as glucose (C6 H12 O6). In oceans, photosynthesis is carried out by microscopic aquatic plants called phytoplankton. iv. The carbohydrates then become the source of chemical energy that fuel living cells in all plants and animals. In plants, some carbon remains as simple glucose for short–term energy use, while some are converted to large complex molecules such as starch for longer term energy storage. SESSION 3. THE CARBON CYCLE 85

SESSION 4 OXYGEN CYCLE 4.1 Mind Map 4.2 Terminology i. Oxygen cycle –The oxygen cycle is the biogeochemical cycle that describes the move- ment of oxygen within its three main reservoirs: the atmosphere (air), the total con- tent of biological matter within the biosphere (the global sum of all ecosystems), and the lithosphere (Earth’s crust). ii. Ozone Depletion –Destruction of the ozone layer which shields the earth from ultravi- olet radiation. iii. BOD – The content of the biodegradable substance in water is expressed by a special index called Biological Oxygen Demand (BOD). SESSION 4. OXYGEN CYCLE 86

iv. CFCs –CFCs (Chloro Fluoro Carbons) are the chemicals which contain carbon, chlo- rine, and fluorine, used in air conditioners and refrigerators which cause a destruction of ozone layer present in the stratosphere of the atmosphere. 4.3 Key Concepts i. Earth’s atmosphere is divided into troposphere and stratosphere. ii. Ozone is a molecule containing three oxygen atoms. It is blue in colour and has a strong odour. iii. Montreal protocol is associated with ozone depletion and greenhouse gases. iv. The ozone layer absorbs a portion of the radiation from the sun, preventing it from reaching the planet’s surface. 4.4 Conceptual Understanding Q1. What emissions from human activities lead to ozone depletion? And what are the prin- cipal steps in stratospheric ozone depletion caused by human activities? [Refer to TB page 182 Q2] A. i. Chlorofluorocarbons and carbon dioxide and other gases emitted from vehicles, industries etc. lead to the ozone layer depletion. ii. Certain industrial processes and consumer products result in the emission of ozone–depleting substances to the atmosphere. iii. These gases bring chlorine and bromine atoms to the stratosphere, where they destroy ozone in chemical reactions. iv. Important examples are the chlorofluorocarbons (CFCs) used in almost all refrig- eration and air conditioning systems. v. Most of these gases accumulate in the lower atmosphere because they are unre- active and do not dissolve readily in rain or snow. vi. Natural air motions transport these accumulated gases to the stratosphere, where they are converted to more reactive gases. vii. Some of these gases then participate in reactions that destroy ozone. viii. The ozone hole is not really a hole, but it was observed that there is less ozone in Antarctica than in the arctic region. SESSION 4. OXYGEN CYCLE 87

4.5 Appreciation and Aesthetic Sense, Values Q1. What do you understand by ozone layer? Write an essay to participate in elocution competition on the importance of ozone layer. [Refer to TB page 182 Q8] A. The Earth’s atmosphere is divided into several layers. The lowest region, the tropo- sphere, extends from the Earth’s surface up to about 10 kilometers (km) in altitude. The next layer, the stratosphere, continues from 10 km to about 50 km. Most atmospheric ozone is concentrated in a layer in the stratosphere, about 15–30 kilometers above the Earth’s surface. The student can make use of following points and create a add–on for writing the essay. i. Ozone is a molecule containing three oxygen atoms. It is blue in colour and has a strong odour. Normal oxygen, which we breathe, has two oxygen atoms and is colourless and odourless. ii. Ozone is much less common than normal oxygen. iii. Out of each 10 million air molecules, about 2 million are normal oxygen, but only 3 out of 10 millions are ozone. iv. However, even the small amount of ozone plays a key role in the atmosphere. The ozone layer absorbs a portion of the radiation from the sun, preventing it from reaching the earth’s surface. Most important of all it absorbs the portion of ultraviolet light which causes many harmful effects, including various types of skin cancer and harm to some crops, certain materials, and some forms of marine life. 4.6 Application to Daily Life, Concern to Bio Diversity Q1. Prepare an article for newspaper on the item “How human activities effects the environ- ment” [Refer to TB page 182 Q13] A. It’s interesting to note that modern humans have been around for a very long time and lived for much of it without causing much irreparable damage to the environment. How- ever, over exploitation and pollution have started affecting the environment negatively over the last few centuries. Negative Impacts Caused by Humans SESSION 4. OXYGEN CYCLE 88

Unfortunately, humans are the most polluting species. Earth is very good at recycling waste, but we are generating far more than earth can cope with. Pollution occurs at different levels and it doesn’t just impact our planet; it impacts all species, including mankind, who dwell on it. Soil pollution: Pesticides, herbicides, large landfills, waste from food processing industries, and nuclear waste generated from nuclear reactors and weapons deplete our soil of its nutrients and make it virtually lifeless. According to the Environmental Protection Agency, ”Usually, contaminants in the soil are physically or chemically attached to soil particles, or, if they are not attached, are trapped in the small spaces between soil particles.” Water Pollution: Effluence from industries, fertilizer run off, and oils spills all damage fragile ecosystems. According to the Water Project, “Nearly a billion people do not have access to clean and safe water in our world.” World watch Institute says, “The 450 million kilograms of pesticides U.S. farmers use every year have now contaminated almost all of the nation’s streams and rivers, and the fish living in them, with chemicals that cause cancer and birth defects.” Air Pollution: Burning of fossil fuels and toxic gases produced in factories causes pollution. Air pollu- tion infects the environment and threatens the health of all who inhabit the earth. Ac- cording to the United Nations, “The estimations we have now tell us there are 3.5 million premature deaths every year caused by household air pollution, and 3.3 million deaths every year caused by outdoor air pollution.” Global Warming and Ozone Layer Depletion: Carbon footprint is the measure of direct or indirect CO2 . Greenhouse gases like CO2 and methane are believed to lead to global warming. Chlorofluorocarbons (CFCs), used in refrigeration, and aerosols destroy the ozone layer that shields the earth from UV rays. SESSION 4. OXYGEN CYCLE 89

—— CCE Based Practice Questions —— AS1-Conceptual Understanding Very Short Answer Type Questions 1. State true or false. [Refer to Session 11.1 ] (i) Water is constantly recycled in a process known as the hydrological or water cycle. [] (ii) Water is considered as a biogeochemical cycle by most ecologists. ] [ (iii) Water is a universal solvent and essential for various reactions to take place in a living cell. [] (iv) Fresh water available is about 10%. [] (v) Water participates in many biogeochemical metabolisms. [ ] 2. Fill in the blanks. [Refer to Session 11.1 ] (vi) Water is constantly recycled in a process known as the . (vii) Water is a and essential for various to take place within a living cell. (viii) Nearly % of all the water on the earth is in the oceans. (ix) All living organisms together constitute only of water on earth. (x) determine the path of transfer of matter on earth. CHAPTER 11. BIOGEOCHEMICAL CYCLES 90

(xi) Dissolution of some harmful substances like SO2 and oxides of nitrogen in rain water leads to . (xii) The human body is composed of about % of water. (xiii) Biogeochemical cycles, from name itself, include , and pathways. (xiv) Water provides and that form an integral part of basic organic compounds of life. (xv) Water is the precursor of major elements viz and . 3. Match the following. Column B [(Session 11.2)] a. Legumes Column A i. Rhizobium ii. Nitrosomonas b. N2 iii. Ammonification c. NH3 iv. Assimilation d. NH4+ v. Denitrification e. Nitrogen Fixation 4. Fill in the blanks. [Refer to Session 11.3 ] (xvi) Graphite consists of element. (xvii) Byproducts of combustion of hydrocarbons are and gases. (xviii) In photosynthesis, energy from sunlight is converted into energy. (xix) Carbon dioxide level in the atmosphere has increased significantly as a result of human use of . CHAPTER 11. BIOGEOCHEMICAL CYCLES 91

(xx) Carbon buried under the ocean floor might take million years to return to the atmosphere. (xxi) A is a small house made of glass that is used to grow plants. (xxii) change waste material in to H2 S and other poisonous and foul smelling substances. (xxiii) and act as natural greenhouse gases. (xxiv) is a primary greenhouse gas. (xxv) affects the weather patterns on earth and causes climate change. 5. Match the following. Column B [(Session 11.4)] a. 97% of water on earth Column A i. Nitrogen ii. Oxygen b. 21% in air iii. Carbon dioxide c. 78% in air iv. Fresh water d. 0.04% in air v. Salt water e. 3% of water on earth 6. Fill in the blanks. [Refer to Session 11.4 ] (xxvi) Most atmospheric is concentrated in a layer in the stratosphere. (xxvii) The ozone layer is present about above the earth’s surface. (xxviii)Ultraviolet rays cause in living organisms. CHAPTER 11. BIOGEOCHEMICAL CYCLES 92

(xxix) is a substance used in refrigerators and air conditioners that destroys the ozone layer. (xxx) There is in Antarctica than in the Arctic region. Short Answer Type Questions 7. Answer the following questions in 3-4 sentences. (i) [(Session 11.1)] What are biogeochemical pathways ? (ii) [(Session 11.1)] What trouble do you encounter with water cycle? 8. Answer the following questions in 3-4 sentences. (i) [(Session 11.4)] Write any two points on Biological Oxygen Demand. (ii) [(Session 11.4)] What are the uses of oxygen? AS2-Asking questions and making hypothesis Short Answer Type Questions 9. Answer the following questions in 3-4 sentences. (i) [(Session 11.1)] Abhishek said that water is found in different states during water cycle. Name the different states of water giving examples for each from the water cycle. (ii) [(Session 11.1)] Prepare a questionnaire on water cycle. AS4-Information skills and projects Long Answer Type Questions 10. Answer the following questions in 6-8 sentences. (i) [(Session 11.1)] Collect details of statistical data about the presence of water on earth. Deduce what percentage of water is available as fresh water. AS5-Communication through drawing and model making Long Answer Type Questions 11. Answer the following questions in 6-8 sentences. (i) [(Session 11.2)] Sketch a flow chart which describes the process of nitrogen fixation. CHAPTER 11. BIOGEOCHEMICAL CYCLES 93

AS6-Appreciation and aesthetic sense, Values Short Answer Type Questions 12. Answer the following questions in 3-4 sentences. (i) [(Session 11.4)] What has caused holes in the ozone layer? Are they good for us? (ii) [(Session 11.4)] Write a short note on ozone layer. How can we protect it ? Long Answer Type Questions 13. Answer the following questions in 6-8 sentences. (i) [(Session 11.3)] How would you appreciate carbon as the “central element of life”? 14. Answer the following questions in 6-8 sentences. (i) [(Session 11.4)] What are the causes of ozone depletion? How would you appreciate the emergence of Montreal protocol towards ozone depletion? AS7-Application to daily life, concern to bio diversity Short Answer Type Questions 15. Answer the following questions in 3-4 sentences. (i) [(Session 11.3)] State in brief the roles of photosynthesis and respiration in carbon cycle in nature. (ii) [(Session 11.3)] We know that an increase in the carbon dioxide level causes an adverse effect on biodiversity in nature. State the reason behind the increasing levels of carbon dioxide in the atmosphere. Long Answer Type Questions 16. Answer the following questions in 6-8 sentences. (i) [(Session 11.1)] Explain how human involvement has affected the water cycle. 17. Answer the following questions in 6-8 sentences. (i) [(Session 11.3)] Explain how human intervention has affected carbon cycle and has caused increased carbon dioxide levels. What are the effects of increased carbon dioxide levels on earth? CHAPTER 11. BIOGEOCHEMICAL CYCLES 94

Objective Questions AS1-Conceptual Understanding 18. Choose the correct answer. (i) Which of the following is responsible for maintaining the earth as a greenhouse with temperature conditions suitable for life? (A) Oxygen (B) CO2 (C) Hydrogen (D) Nitrogen (ii) Proteins contain (A) Carbon (B) Nitrogen (C) Oxygen (D)All of these (iii) The main reservoirs of carbon are (A) Sedimentary rocks (B) Fossil fuels (C) Oceans (D)All the above (iv) Oxygen is returned to the atmosphere mainly by (A) Respiration (B) Photosynthesis (C)Burning of wood (D) Fungi (v) Excessive amount of carbon dioxide and other green houses are emitted to the environment due to (A) Burning of fossil fuels, deforestation (B) Burning of fossil fuels, industrialization (C)Deforestation, industrialization (D)Burning of fossil fuels, deforestation, industrialisation (vi) Ozone layer is getting depleted because of CHAPTER 11. BIOGEOCHEMICAL CYCLES 95

(A) Industrial units (B) Automobiles (C) CFCs (D) None (vii) exists in the biosphere as the central element of life. (A) Carbon (B) Nitrogen (C) Oxygen (D) Water (viii) Which of the following gas protects the earth from ultraviolet radiations? (A) Nitrogen (B) Oxygen (C) Ozone (D) Hydrogen (ix) Carbon dioxide now makes up about by volume of air. (A) 0.05% (B) 0.04% (C) 0.1% (D) 1% (x) To protect ozone layer, the protocol emerged was (A) Washington protocol (B) Montreal protocol (C)Vancover protocol (D)Geneva protocol (xi) In biogeochemical cycles, there is a constant interaction between: (A) Biotic and Abiotic components of biosphere (B) Flora and Fauna in the biosphere (C)Biological, Geological, Chemical and Physiological components of biosphere (D)Both A and C (xii) Which cycle is also known as hydrological cycle? (A) Water cycle (B) Nitrogen cycle (C)Carbon cycle (D)Oxygen cycle CHAPTER 11. BIOGEOCHEMICAL CYCLES 96

(xiii) Which of the following is not a green house gas? (A) Carbon dioxide (B) Methane . (C)Carbon monoxide (D) Nitrogen (xiv) Denitrification refers to conversion of to (A) Nitrate to Ammonia (B) Solid nitrate to gaseous nitrogen (C)Nitrate to Nitrite (D)All of the above (xv) The process of converting atmospheric nitrogen into more available organic forms is called as: (A) Nitrogen assimilation (B) Ammonification (C)Nitrogen fixation (D) Denitrification (xvi) Which of the following element is referred as the central element of life? (A) Hydrogen (B) Oxygen (C) Carbon (D) Nitrogen (xvii) In the process of photosynthesis, carbon dioxide and water combine in the pres- ence of light energy to produce molecules. (A) Starch (B) Sucrose (C) Glucose (D) Fructose (xviii) Which gases are produced as a by product of combustion of hydrocarbons? (A) CO2 and CO (B) NO2 and CO2 (C)CO2 and SO2 (D)CO2 and O2 (xix) The phenomenon of naturally warming of earth leading to increase in global temperature is known as: (A) Green–house effect (B) Global warming (C)Global climate change (D)All of the above CHAPTER 11. BIOGEOCHEMICAL CYCLES 97

(xx) Most atmospheric ozone which protects the earth from harmful ultraviolet radia- tions of the Sun is present in which layer of the atmosphere? (A) Troposphere (B) Stratosphere (C) Ionosphere (D) Exosphere CHAPTER 11. BIOGEOCHEMICAL CYCLES 98