Class 10 Social Science Geography Chapter 2 Question Answer | Environment and Environmental Problems | English Medium

Class 10 Social Science Geography Chapter 2 Question Answer | Environment and Environmental Problems | English Medium | ASSEB

Class 10 Social Science Geography Chapter 2 — Environment and Environmental Problems

Welcome to HSLC Guru. This chapter introduces the environment, its components, ecosystem dynamics, and the major environmental problems facing the world today. The notes below align with the ASSEB (Assam State School Education Board) Class 10 Social Science syllabus and cover summary, textbook Q&A, additional questions, and a glossary.

Summary

The environment refers to the total surroundings in which an organism lives. It is the sum of all external conditions — physical, chemical, and biological — that affect the life and growth of organisms. The environment has two broad components: the physical (abiotic) environment, made up of non-living elements such as land, water, air, sunlight, and temperature; and the biotic environment, made up of all living organisms — plants, animals, and microorganisms. The Earth’s environment is organised into four interlinked spheres: the atmosphere (the layer of gases surrounding the Earth), the hydrosphere (all water bodies — oceans, rivers, lakes, groundwater, ice caps), the lithosphere (the solid crust of the Earth including soil and rocks), and the biosphere (the zone where life exists, formed by the overlap of the other three spheres).

An ecosystem is a functional unit of nature where living organisms (biotic components) interact with non-living surroundings (abiotic components) and exchange matter and energy. Ecosystems may be terrestrial (forest, grassland, desert) or aquatic (pond, river, ocean). Within an ecosystem, energy flows in one direction through a food chain — for example, grass → grasshopper → frog → snake → eagle. Several interconnected food chains form a food web. Energy from the Sun enters the ecosystem through producers (green plants) by photosynthesis and passes to consumers and decomposers, with about 90% lost as heat at each trophic level (10% law). Nutrients such as carbon, nitrogen, oxygen, and water move through living and non-living systems via biogeochemical cycles, which keep the biosphere balanced.

Human activities have caused several environmental problems. Air pollution is caused by harmful gases such as sulphur oxides (SOx), nitrogen oxides (NOx), carbon oxides (COx), particulate matter, and lead released from vehicles, industries, and burning of fossil fuels. It produces effects like smog (a mix of smoke and fog) and acid rain (rain made acidic by SO2 and NO2), which damages crops, soil, water bodies, and monuments. Water pollution results from sewage, industrial effluents, agricultural runoff (fertilizers and pesticides), and oil spills, leading to eutrophication — over-enrichment of water with nutrients causing algal blooms and oxygen depletion. Soil pollution is caused by chemical fertilizers, pesticides, plastic waste, and industrial dumping. Noise pollution from traffic, factories, loudspeakers, and construction harms hearing and mental health. Deforestation reduces forest cover, causing soil erosion, loss of biodiversity, and climate imbalance.

Global warming is the gradual rise in the Earth’s average temperature due to the increased concentration of greenhouse gases (CO2, CH4, N2O, water vapour, CFCs) in the atmosphere — the greenhouse effect. It melts polar ice, raises sea levels, and changes climate patterns. Ozone layer depletion in the stratosphere is caused mainly by chlorofluorocarbons (CFCs) used in refrigerators, air conditioners, and aerosols; the resulting “ozone hole” allows harmful ultraviolet radiation to reach the Earth. The Montreal Protocol (1987) was signed to phase out ozone-depleting substances. The United Nations has held several Earth Summits — the Rio Earth Summit (1992) on environment and development, the Kyoto Protocol (1997) on reducing greenhouse-gas emissions, and the Paris Agreement (2015) to limit global temperature rise below 2°C. Conservation measures include afforestation, sustainable development, the 3Rs (Reduce, Reuse, Recycle), pollution-control acts, the National Green Tribunal (NGT, 2010), and active participation by individuals through tree planting, energy saving, and waste segregation.

Textbook Question Answers

1-Mark Questions

Q1. What is environment?

Answer: Environment is the total of all external conditions — physical, chemical, and biological — that surround and influence the life of an organism.

Q2. Name the four components (spheres) of the environment.

Answer: Atmosphere, Hydrosphere, Lithosphere, and Biosphere.

Q3. What is the biosphere?

Answer: The biosphere is the zone of the Earth where life exists, formed by the interaction of the atmosphere, hydrosphere, and lithosphere.

Q4. Define an ecosystem.

Answer: An ecosystem is a functional unit of nature in which living organisms (biotic components) interact with the non-living environment (abiotic components) and exchange matter and energy.

Q5. What is a food chain?

Answer: A food chain is the sequence in which one organism eats another and energy is transferred from producers to consumers in an ecosystem.

Q6. Name two greenhouse gases.

Answer: Carbon dioxide (CO2) and Methane (CH4).

Q7. Which gas is mainly responsible for ozone-layer depletion?

Answer: Chlorofluorocarbons (CFCs).

Q8. When was the Montreal Protocol signed?

Answer: The Montreal Protocol was signed in 1987.

Q9. What does 3R mean in environmental conservation?

Answer: Reduce, Reuse, and Recycle.

Q10. When was the National Green Tribunal (NGT) established in India?

Answer: The National Green Tribunal was established in 2010.

2-3 Marks Questions

Q1. Distinguish between abiotic and biotic components of the environment.

Answer: Abiotic components are the non-living elements of the environment such as air, water, soil, sunlight, and temperature. Biotic components are all living organisms — plants, animals, and microorganisms. The two interact constantly: abiotic factors provide the conditions and resources, while biotic factors use and modify them.

Q2. What is acid rain? How is it caused?

Answer: Acid rain is rainfall that has been made acidic (pH below 5.6) by atmospheric pollution. It is caused when sulphur dioxide (SO2) and nitrogen oxides (NOx) released from factories and vehicles combine with water vapour in the atmosphere to form sulphuric acid and nitric acid. It damages crops, forests, soil, aquatic life, and stone monuments such as the Taj Mahal.

Q3. Explain the difference between food chain and food web.

Answer: A food chain is a single straight pathway of energy transfer in which each organism eats the one before it (e.g., grass → rabbit → fox). A food web is a network of many interconnected food chains in an ecosystem, showing that most organisms feed on more than one type of food, which makes the system more stable.

Q4. What is eutrophication?

Answer: Eutrophication is the over-enrichment of a water body with nutrients (mainly nitrates and phosphates) from sewage and agricultural runoff. It causes excessive growth of algae (algal bloom), which depletes dissolved oxygen when the algae decay, killing fish and other aquatic life.

Q5. Mention any three causes of deforestation.

Answer: (i) Expansion of agriculture and shifting cultivation. (ii) Construction of dams, roads, and settlements. (iii) Commercial logging for timber, paper, and fuelwood, and forest fires.

Q6. Write a short note on the Paris Agreement (2015).

Answer: The Paris Agreement was adopted at the 21st UN Climate Change Conference (COP21) in Paris in December 2015. It is a legally binding international treaty in which member countries agreed to limit the rise in global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to keep it below 1.5°C, mainly by reducing greenhouse-gas emissions.

Q7. What is meant by sustainable development?

Answer: Sustainable development is a process of using natural resources wisely so as to meet the needs of the present generation without compromising the ability of future generations to meet their own needs. It balances economic growth, social welfare, and environmental protection.

Q8. Mention any three sources of noise pollution.

Answer: (i) Heavy road, rail, and air traffic. (ii) Industrial machinery, generators, and construction equipment. (iii) Loudspeakers, firecrackers, and household appliances. Prolonged exposure causes hearing loss, hypertension, and stress.

5-6 Marks Questions

Q1. Describe the four components (spheres) of the environment.

Answer: The environment is made up of four interlinked spheres: (i) Atmosphere — the gaseous envelope around the Earth, made up mainly of nitrogen (78%) and oxygen (21%), which provides air to breathe, protects from harmful radiation, and controls weather. (ii) Hydrosphere — all the water on Earth, including oceans, rivers, lakes, groundwater, and ice; it covers about 71% of the Earth’s surface and is essential for life. (iii) Lithosphere — the solid outer crust of the Earth, including soil, rocks, and minerals, which provides land for living, agriculture, and resources. (iv) Biosphere — the zone where life exists, formed where the other three spheres overlap; it includes all plants, animals, and microorganisms. These spheres interact constantly to keep the Earth habitable.

Q2. What is air pollution? Discuss its main causes and effects.

Answer: Air pollution is the contamination of the atmosphere by harmful gases, dust, smoke, and other pollutants released by human and natural activities. Main causes: (i) Burning of fossil fuels (coal, petrol, diesel) in vehicles and power stations releasing CO, CO2, SO2, NOx; (ii) Industrial emissions of toxic gases and particulate matter; (iii) Domestic burning of wood, kerosene, and waste; (iv) Agricultural activities — burning of stubble, use of pesticides; (v) Volcanic eruptions and forest fires (natural). Effects: (i) Respiratory diseases such as asthma, bronchitis, and lung cancer; (ii) Acid rain, which damages crops, soil, water bodies, and monuments; (iii) Smog reducing visibility and harming health; (iv) Global warming due to greenhouse gases; (v) Depletion of the ozone layer increasing harmful UV radiation; (vi) Damage to plants and reduction of agricultural yield.

Q3. Explain the greenhouse effect and global warming. What are their consequences?

Answer: The greenhouse effect is the natural process by which gases like CO2, CH4, N2O, water vapour, and CFCs in the atmosphere trap heat from the Sun and keep the Earth warm enough to support life. However, human activities — burning fossil fuels, deforestation, industrialisation, and farming — have greatly increased the concentration of these greenhouse gases, intensifying the effect. This rise in the Earth’s average temperature is called global warming. Consequences: (i) Melting of glaciers and polar ice caps; (ii) Rise in sea level submerging low-lying coastal areas and islands; (iii) Frequent and severe floods, droughts, cyclones, and heatwaves; (iv) Loss of biodiversity and extinction of species; (v) Decline in agricultural production and food insecurity; (vi) Spread of diseases like malaria and dengue; (vii) Disturbance of ocean currents and monsoons.

Q4. Suggest measures for the conservation of the environment.

Answer: Important measures for conservation of the environment include: (i) Afforestation and reforestation — planting trees to increase forest cover and prevent soil erosion. (ii) Sustainable development — using natural resources in a way that meets present needs without harming future generations. (iii) Practising the 3Rs — Reduce, Reuse, and Recycle — to minimise waste. (iv) Use of renewable energy sources such as solar, wind, hydro, and biogas in place of fossil fuels. (v) Pollution-control laws such as the Water (Prevention and Control of Pollution) Act 1974, the Air Act 1981, and the Environment (Protection) Act 1986. (vi) Establishment of the National Green Tribunal (NGT) in 2010 for speedy disposal of environmental cases. (vii) International cooperation through the Montreal Protocol, Kyoto Protocol, and Paris Agreement. (viii) Public awareness and education, observance of Earth Day and World Environment Day. (ix) Individual actions — saving water and electricity, avoiding plastics, segregating waste, using public transport, and planting trees.

Q5. Write briefly about the major UN Earth Summits and protocols on the environment.

Answer: (i) Stockholm Conference (1972) — the first UN conference on the human environment, which led to the founding of UNEP. (ii) Montreal Protocol (1987) — an international treaty to phase out the production and use of ozone-depleting substances such as CFCs. (iii) Rio Earth Summit (1992) — held at Rio de Janeiro, Brazil; it produced Agenda 21, the Convention on Biological Diversity, and the UN Framework Convention on Climate Change (UNFCCC). (iv) Kyoto Protocol (1997) — adopted at Kyoto, Japan; legally bound developed countries to reduce greenhouse-gas emissions. (v) Johannesburg Summit (2002) — focused on sustainable development. (vi) Paris Agreement (2015) — committed countries to keep the global temperature rise below 2°C and to pursue efforts to limit it to 1.5°C through national contributions and climate finance.

Q6. What are the main causes and effects of water pollution? Suggest some preventive measures.

Answer: Causes of water pollution: (i) Discharge of untreated sewage and household waste into rivers and lakes. (ii) Industrial effluents containing heavy metals, dyes, oils, and toxic chemicals. (iii) Agricultural runoff carrying chemical fertilizers and pesticides. (iv) Oil spills from tankers and offshore drilling. (v) Religious and social activities such as immersion of idols and dumping of waste. Effects: (i) Spread of waterborne diseases such as cholera, typhoid, dysentery, and jaundice. (ii) Death of fish and other aquatic organisms due to oxygen depletion (eutrophication). (iii) Loss of biodiversity in rivers, ponds, and oceans. (iv) Damage to crops when polluted water is used for irrigation. (v) Contamination of groundwater that humans depend upon for drinking. Preventive measures: Treat sewage before discharge, set up effluent-treatment plants in factories, encourage organic farming, ban single-use plastics, conserve wetlands, and create public awareness through events like World Water Day.

Additional Multiple-Choice Questions (MCQ)

Q1. The non-living components of the environment are called —

(a) Biotic (b) Abiotic (c) Organic (d) Living

Answer: (b) Abiotic.

Q2. Which of the following is not a sphere of the environment?

(a) Atmosphere (b) Hydrosphere (c) Stratosphere (d) Biosphere

Answer: (c) Stratosphere.

Q3. The most abundant gas in the atmosphere is —

(a) Oxygen (b) Nitrogen (c) Carbon dioxide (d) Argon

Answer: (b) Nitrogen.

Q4. Which gas is mainly responsible for the greenhouse effect?

(a) Oxygen (b) Nitrogen (c) Carbon dioxide (d) Hydrogen

Answer: (c) Carbon dioxide.

Q5. Acid rain is mainly caused by —

(a) CO2 and CH4 (b) SO2 and NO2 (c) O2 and N2 (d) CFCs

Answer: (b) SO2 and NO2.

Q6. The Montreal Protocol deals with —

(a) Climate change (b) Ozone-layer depletion (c) Biodiversity (d) Wetlands

Answer: (b) Ozone-layer depletion.

Q7. The Earth Summit was held at Rio de Janeiro in —

Answer: (b) 1992.

Q8. The Paris Agreement was adopted in —

Q9. Excessive growth of algae in water bodies is called —

(a) Acidification (b) Eutrophication (c) Deforestation (d) Salinisation

Answer: (b) Eutrophication.

Q10. The National Green Tribunal was established in —

Q11. The 10% Law of energy flow in an ecosystem was given by —

(a) Tansley (b) Lindeman (c) Odum (d) Darwin

Answer: (b) Lindeman.

Q12. The Kyoto Protocol was related to —

(a) Wildlife protection (b) Reducing greenhouse gas emissions (c) Wetland conservation (d) Marine pollution

Answer: (b) Reducing greenhouse gas emissions.

Fill in the Blanks

1. The zone of the Earth where life exists is called the __________.

Answer: Biosphere.

2. The 3Rs of conservation are Reduce, Reuse, and __________.

Answer: Recycle.

3. The Kyoto Protocol was adopted in the year __________.

Answer: 1997.

4. __________ are the chief substances responsible for ozone-layer depletion.

Answer: Chlorofluorocarbons (CFCs).

5. A network of interconnected food chains is called a __________.

Answer: Food web.

True / False

1. The hydrosphere includes all the water bodies on the Earth.

Answer: True.

2. Plants are the consumers in an ecosystem.

Answer: False (Plants are producers).

3. The Paris Agreement aims to limit global warming to well below 2°C.

Answer: True.

4. Noise pollution has no effect on human health.

Answer: False.

5. The National Green Tribunal handles environmental cases in India.

Answer: True.

Additional Short Questions and Answers

Q1. What is meant by the trophic level in an ecosystem?

Answer: A trophic level is the position an organism occupies in a food chain. Producers (green plants) form the first trophic level, herbivores (primary consumers) form the second, carnivores (secondary consumers) form the third, and top carnivores form the highest. Energy is transferred from one trophic level to the next, with about 90% lost as heat at every step.

Q2. Why are decomposers important in an ecosystem?

Answer: Decomposers (bacteria and fungi) break down the dead bodies of plants and animals into simple inorganic substances. They release nutrients back into the soil, water, and air, completing the biogeochemical cycles. Without decomposers, dead matter would pile up and the flow of nutrients in nature would stop.

Q3. List four major greenhouse gases.

Answer: Carbon dioxide (CO2), Methane (CH4), Nitrous oxide (N2O), and Chlorofluorocarbons (CFCs). Water vapour is also a natural greenhouse gas.

Q4. What role can students and individuals play in conserving the environment?

Answer: Individuals can: (i) plant trees and protect existing forests; (ii) save water and electricity at home; (iii) practise the 3Rs — Reduce, Reuse, Recycle; (iv) avoid plastic bags and segregate waste; (v) use bicycles or public transport; (vi) participate in clean-up drives and awareness programmes; (vii) celebrate Earth Day, Van Mahotsav, and World Environment Day.

Q5. Mention three major environmental Acts passed in India.

Answer: (i) The Water (Prevention and Control of Pollution) Act, 1974. (ii) The Air (Prevention and Control of Pollution) Act, 1981. (iii) The Environment (Protection) Act, 1986. The Wildlife (Protection) Act, 1972 and the Forest (Conservation) Act, 1980 are also significant.

Glossary

Term	Meaning
Environment	The total of all external physical, chemical, and biological conditions surrounding an organism.
Abiotic	The non-living components of the environment — air, water, soil, sunlight, temperature.
Biotic	The living components of the environment — plants, animals, microorganisms.
Atmosphere	The layer of gases surrounding the Earth.
Hydrosphere	All the water bodies on the Earth — oceans, rivers, lakes, groundwater, ice.
Lithosphere	The solid outer crust of the Earth including soil and rocks.
Biosphere	The zone of the Earth where life exists.
Ecosystem	A functional unit of nature where living and non-living components interact and exchange energy.
Food chain	A linear sequence of organisms in which each one eats the previous one for energy.
Food web	A network of many interconnected food chains in an ecosystem.
Biogeochemical cycle	The cyclic flow of nutrients (carbon, nitrogen, oxygen, water) between living organisms and the environment.
Pollution	The contamination of air, water, soil, or noise environment by harmful substances.
Smog	A mixture of smoke and fog formed by air pollutants in cities.
Acid rain	Rain that has been made acidic by atmospheric pollutants like SO2 and NO2.
Eutrophication	Over-enrichment of water bodies with nutrients leading to algal blooms and oxygen loss.
Deforestation	Large-scale clearing or destruction of forests by humans.
Greenhouse effect	Trapping of heat in the Earth’s atmosphere by greenhouse gases.
Global warming	The gradual rise in Earth’s average temperature due to increased greenhouse gases.
Ozone layer	A layer in the stratosphere that absorbs harmful ultraviolet radiation from the Sun.
CFCs	Chlorofluorocarbons — chemicals that destroy the ozone layer.
Montreal Protocol (1987)	International treaty to phase out ozone-depleting substances.
Rio Earth Summit (1992)	UN Conference on Environment and Development held at Rio de Janeiro.
Kyoto Protocol (1997)	Treaty binding developed nations to reduce greenhouse-gas emissions.
Paris Agreement (2015)	Global climate accord to limit warming below 2°C above pre-industrial levels.
Sustainable development	Development that meets present needs without compromising the needs of future generations.
3Rs	Reduce, Reuse, and Recycle — strategy for waste management.
Afforestation	Planting of trees in areas where there were no forests earlier.
National Green Tribunal (NGT)	Indian special court (established 2010) for environmental cases.