15. Our Environment Science class 10 in English Medium ncert book solutions Exercise

NCERT Solutions Exercise

Q1. Which of the following groups contain only biodegradable items?  (a) Grass, flowers and leather 

(b) Grass, wood and plastic

(c) Fruit-peels, cake and lime-juice

(d) Cake, wood and grass

Ans. Grass, wood and plastic.

Q2. Which of the following constitute a food-chain?

(a) Grass, wheat and mango

(b) Grass, goat and human

(c) Goat, cow and elephant

(d) Grass, fish and goat

Ans. Grass, goat and human.

Q3. Which of the following are environment-friendly practices?

(a) Carrying cloth-bags to put purchases in while shopping.

(b) Switching off unnecessary lights and fans.

(c) Walking to school instead of getting your mother to drop you on her scooter.

(d) All of the above. 

Ans. All of the above.

Q4. What will happen if we kill all the organisms in one trophic level?

Ans. If we kill all the organisms in one trophic level the transfer of food energy tothe next trophic level will stop this will cause a break in the food chain resulting in esosystem imbalance.

Q5. Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

Ans. Yes, the impact of removing all the arganisms in a trophic level be different for different trophic levels. If all the produced are killed. If will cause death or migration of the primary consumers in the ecosystem. 

Q6. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Ans. Progressive increase in the concentration of non-biodegradable substance in a food chain is called biological magnification. The level of these harmful substence will go on increasing food onne trophic level.

Q7. What are the problems caused by the non-biodegradable wastes that we generate?

Ans: The non-biodegradable waste produced by us pollutes the environment. They do not decompose. Hence the problem of on-key disposal also comes. This creates many problems.

(i) Decrease the members of the ecosystem.

(ii) increase the biomagnification by creating it.

(iii) Water, land and air pollute.

Q8. If all the waste we generate is biodegradable, will this have no impact on the environment?

Ans: Biodegradable waste pollutes the environment only for a limited period of time. After this, it gets destroyed when it is destroyed and is also useful in recycling. After their decomposition, odor and toxic gases are generated in the atmosphere.

Q9. Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

Ans: The ozone layer O3 protects us from the harmful ultraviolet radiations of the sun. Due to its damage, it causes skin diseases and skin cancer by reaching the radiations to the earth. So this is a matter of concern for us. Chlorofluorocarbons, which are used in refrigerators and fire extinguishers, are damaging ozone. To limit this damage, we should minimize the use of chlorofluorocarbons and chemical substances.