NCERT Solutions for class 10 Science Chapter 15:Our Environment

NCERT Solutions for class 10 Science Chapter 15 Exercise Question

Question 1

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

Answer

a) Grass, flowers and leather

Question 2

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

Answer

b. Grass, goat and human

Question 3

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

Answer

d) All of the above

Question 4

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

Answer

If we kill all the organisms in one trophic level, the food supply to the next level will strop resulting the lower trophic level will grow more in an enormous way and the higher trophic level will die . So flow of energy from one trophic level to other will not take place.

Question 5

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

Answer

Yes The impact for removing different organisms at different trophic levels would be different as the removal of organisms at any level would upset the whole ecosystem and the food chain is disturbed For e.g - If all snakes are killed, the peacocks belonging to the next level will also die. Also the population of rats in the preceding level will highly increase, if grasshoppers are removed frogs will starting reducing in number.Thus to maintain the balance of the ecosystem the presence of organisms is necessary at each trophic level.

Question 6

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

Answer

Biomagnification is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain.Yes all the other levels get affected and the concentration vary compared to first level and also affect their biological process such as growth.

Question 7

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

Answer

The problems caused by the non-biodegradable wastes are follow:

i)These substances cannot be decomposed by the microorganisms.

ii)The quantity of non-biodegradable matter increases in the nature get poisonous .

iii)Death of cattle by ingestion of plastic, toxin remains on plants

(vi) Pollution of air, water and land

Question 8

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

Answer

• Decomposition of the biodegradable wastes produce foul smell which can not inhaled by humans.
• if all the biodegradable waste accumulate on earth, the number of decomposers will increase in the environment. Thus affecting the the food chain.
• Increase in the number of aquatic organisms may result in depletion of oxygen.

Question 9

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

Answer

The ozone layer protecte us from harmful UV rays which coming from the sun to earth. These harmful ultraviolet rays cause skin cancer. But The chlorofluorocarbons (CFCs) which lead air pollution are the main reason for the depletion of the ozone layer .So these are the reasons why damage of ozone layer is a cause of concern.

Steps taken to limit this is that many developing and developed countries an agreement and are follow the directions of UNEP (United Nations Environment Programme) to freeze or limit the production and usage of CFCs.