Short Questions Answer
1. What is an ecosystem?
Answer: An ecosystem is a system formed by the interaction between living organisms and their physical environment.
2. Name two types of ecosystems.
Answer: Natural and artificial (man-made).
3. What are producers?
Answer: Green plants that make their own food by photosynthesis.
4. Who are decomposers?
Answer: Microorganisms like bacteria and fungi that break down dead plants and animals.
5. What is a food chain?
Answer: A sequence of organisms where one is eaten by the next member in the chain.
6. What is a trophic level?
Answer: Each step in a food chain is called a trophic level.
7. What is the 10% law?
Answer: Only 10% of energy is transferred from one trophic level to the next.
8. What is a food web?
Answer: Interconnected food chains in an ecosystem.
9. What is biological magnification?
Answer: Gradual increase in the concentration of harmful chemicals at higher trophic levels.
10. Name one chemical responsible for ozone layer depletion.
Answer: Chlorofluorocarbons (CFCs).
11. What is ozone?
Answer: Ozone is a molecule made up of three oxygen atoms (O₃).
12. What is the function of the ozone layer?
Answer: It protects Earth from harmful ultraviolet (UV) radiation.
13. What are biodegradable substances?
Answer: Substances that can be broken down by microorganisms.
14. Give one example of non-biodegradable waste.
Answer: Plastic.
15. How can we reduce waste generation?
Answer: By reusing and recycling materials.
Long Questions Answer
1. Explain the components of an ecosystem with examples.
Answer: An ecosystem has biotic components (plants, animals, decomposers) and abiotic components (air, water, soil, sunlight).
Example: A pond ecosystem includes fish, algae, insects, water, and sunlight.
2. Describe the flow of energy in an ecosystem.
Answer: Energy flows from the sun → producers → consumers → decomposers.
Only 10% of energy is passed to the next level; the rest is lost as heat. The flow is unidirectional.
3. What is a food chain? Explain with an example.
Answer: A food chain shows who eats whom.
Example: Grass → Grasshopper → Frog → Snake → Eagle.
4. What is a food web? How is it different from a food chain?
Answer: A food web is a network of interconnected food chains.
It shows that one organism can be a part of multiple food chains, unlike a single linear chain.
5. Explain biological magnification with an example.
Answer: Non-degradable chemicals like DDT enter the food chain. Their concentration increases at each trophic level.
Example: Water → Algae → Small fish → Large fish → Human.
6. What is ozone layer depletion? What causes it?
Answer: The ozone layer is thinning due to the release of CFCs from refrigerators and sprays, allowing harmful UV rays to reach Earth.
7. What are biodegradable and non-biodegradable substances? Give examples.
Answer: Biodegradable: Broken down by microbes (e.g., paper, vegetable waste).
Non-biodegradable: Not broken down (e.g., plastic, metals).
8. State three effects of non-biodegradable waste on the environment.
Answer:
- (i) Soil and water pollution
- (ii) Harm to aquatic life
- (iii) Biological magnification in food chains
9. What steps are being taken to reduce ozone layer depletion?
Answer: The 1987 Montreal Protocol limited CFC production; use of CFC-free refrigerators and sprays is being promoted.
10. How can humans manage waste more effectively?
Answer: By segregating waste into biodegradable and non-biodegradable, recycling, composting, and reducing the use of plastics.
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