Q1. Microorganisms are often referred to as the ‘scavengers of the environment.’ Elaborate.
Q2. Give three differences between food chain and food web.
Q3. We often observe domestic waste decomposing in the bylanes of residential colonies. Suggest, ways to make people realise that the improper disposal of waste is harmful to the environment.
Q4. (i) Ultraviolet radiation from sunlight causes a reaction involving O2 as reactant. What does that produce?
(ii) What does release of phosphates and nitrates in waterbodies lead to?
Q5. Why is Government of India imposing a ban on the use of polythene bags? Suggest two alternatives to these bags and explain plainly how this ban is likely to improve the environment.
Q6. State 10% law. Explain with an example of how energy flows through different trophic levels.
Q7. ‘Vegetarian food habits can sustain a larger number of people’. Justify the statement in terms of food chain.
Q8. What is garbage? What does garbage consist of? What is disposal of waste?
Q9. What will happen if we kill all the organisms in one trophic level?
Q10. Give three examples for reducing the problem of waste disposal? Give any two methods.
Q11. You have been selected to talk on ‘ozone layer and its protection’ in the school assembly on ‘Environment Day’.
(a) Why should ozone layer be protected to save the environment?
(b) List any two ways that you would stress in your talk to bring in awareness amongst your fellow friends that would also help in protection of the ozone layer as well as the environment.
Q12. Write the major cause of ozone depletion. What steps should be taken to limit the damage to ozone layer?
Q13. Suggest one word for each of the following statements/definitions
(a) The physical and biological world where we live in.
(b) Each level of food chain where transfer of energy takes place.
(c) The physical factors like temperature, rainfall, wind and soil of an ecosystem.
Q14. How does study of food chain in an area or habitat help us? Give an example of four-step food chain operating in a large lake.