Chapter 20 — Environmental Management: Multiple Choice Questions
1. The main cause of the greenhouse effect and global warming is ______.
Answer
(a) Oxygen (b) Carbon dioxide (c) Nitrogen (d) Hydrogen
✅ Answer: (b) Carbon dioxide
ExplanationGreenhouse gases (CO₂, CH₄, N₂O, water vapour, CFCs) trap heat in the atmosphere by absorbing infrared radiation from Earth's surface. CO₂ is the most significant contributor to global warming due to burning of fossil fuels (coal, oil, gas) and deforestation. Global temperatures are rising, causing climate change.
2. The depletion of the ozone layer is mainly caused by ______.
Answer
(a) Carbon dioxide (b) Chlorofluorocarbons (CFCs) (c) Nitrogen (d) Oxygen
✅ Answer: (b) Chlorofluorocarbons (CFCs)
ExplanationCFCs (used in refrigerators, air conditioners, aerosol sprays) release chlorine atoms in the stratosphere that catalytically destroy ozone (O₃). The ozone layer absorbs harmful UV radiation. Ozone depletion leads to increased UV reaching Earth → skin cancer, cataracts, harm to plankton. CFCs banned by Montreal Protocol (1987).
3. Which of the following is a biodegradable pollutant?
Answer
(a) Plastic (b) DDT (c) Mercury (d) Food waste
✅ Answer: (d) Food waste
Explanation
- Biodegradable: Can be broken down by microorganisms (food waste, paper, cotton, wood, sewage)
- Non-biodegradable: Cannot be broken down (plastic, DDT, heavy metals, glass, radioactive waste)
Non-biodegradable pollutants accumulate in the environment and food chains (biomagnification).
4. The convention that banned the use of CFCs is ______.
Answer
(a) Kyoto Protocol (b) Montreal Protocol (c) Rio Summit (d) Paris Agreement
✅ Answer: (b) Montreal Protocol
Explanation
- Montreal Protocol (1987): International treaty to phase out ozone-depleting substances (CFCs). Highly successful — ozone layer is recovering.
- Kyoto Protocol (1997): Committed developed countries to reduce greenhouse gas emissions.
- Paris Agreement (2015): Aims to limit global warming to 1.5–2°C above pre-industrial levels.
5. The term "biodiversity" was coined by ______.
Answer
(a) E.O. Wilson (b) Charles Darwin (c) Walter G. Rosen (d) Ernst Haeckel
✅ Answer: (c) Walter G. Rosen
ExplanationThe term "biodiversity" was coined by Walter G. Rosen in 1985. It was popularised by E.O. Wilson in his 1988 book. Biodiversity includes: genetic diversity (within species), species diversity (number of species), and ecosystem diversity (variety of habitats).
6. Biomagnification refers to ______.
Answer
(a) Using a microscope to observe organisms (b) Increase in concentration of pollutants up the food chain (c) Increase in population of organisms (d) Reproduction of microorganisms
✅ Answer: (b) Increase in concentration of pollutants up the food chain
ExplanationBiomagnification (bioaccumulation): Toxic pollutants (DDT, mercury, PCBs) cannot be metabolised or excreted. They accumulate in fatty tissues and become progressively more concentrated at higher trophic levels. Top predators (humans, eagles) have the highest concentrations — most harmful effects.
7. The 3Rs of waste management are ______.
Answer
(a) Reduce, Reuse, Recycle (b) Remove, Replace, Repair (c) Renew, Restore, Rebuild (d) Reduce, Remove, Replace
✅ Answer: (a) Reduce, Reuse, Recycle
ExplanationThe 3Rs:
- Reduce: Use less — reduce consumption and waste generation
- Reuse: Use items multiple times before discarding
- Recycle: Convert waste into new products (paper, glass, metal recycling)
Some also add a 4th R: Recover (energy recovery from waste). The order matters — reducing is most important.
8. Which ecosystem has the highest biodiversity?
Answer
(a) Desert (b) Tundra (c) Tropical rainforest (d) Temperate grassland
✅ Answer: (c) Tropical rainforest
ExplanationTropical rainforests (Amazon, Congo, Southeast Asian forests) have the highest biodiversity on Earth. They cover less than 7% of Earth's surface but contain over 50% of all species. Reasons: stable warm/wet climate throughout the year, high productivity, diverse habitats in the vertical layers of the forest.
9. Eutrophication is caused by ______.
Answer
(a) Oil spills (b) Excess nutrients (phosphates, nitrates) in water bodies (c) Industrial effluents with heavy metals (d) Radioactive waste
✅ Answer: (b) Excess nutrients (phosphates, nitrates) in water bodies
ExplanationEutrophication: Enrichment of water bodies with excess nutrients (from fertiliser runoff, sewage) → explosive growth of algae (algal bloom) → algae die → bacteria decompose them → use up all dissolved oxygen → fish and other aquatic organisms die from oxygen depletion (hypoxia). Creates "dead zones."
10. An in-situ method of biodiversity conservation is ______.
Answer
(a) Zoo (b) Botanical garden (c) National park (d) Seed bank
✅ Answer: (c) National park
Explanation
- In-situ conservation: Conservation in the natural habitat. Examples: national parks, wildlife sanctuaries, biosphere reserves, sacred groves. Animals live in their natural environment.
- Ex-situ conservation: Conservation outside natural habitat. Examples: zoos, botanical gardens, aquaria, seed banks, gene banks.
India has 106 national parks, 567 wildlife sanctuaries, and 18 biosphere reserves.
Quick Revision — Environmental Issues
| Issue | Cause | Effect |
|---|
| Global warming | CO₂, CH₄ from fossil fuels | Climate change, melting ice, sea level rise |
| Ozone depletion | CFCs | UV radiation increase, skin cancer |
| Acid rain | SO₂, NOₓ from factories | Damages forests, lakes, buildings |
| Eutrophication | Nutrient runoff | Algal bloom, dead zones |
| Biomagnification | Non-biodegradable toxins | Harm to top predators |
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