Class 10 - Biology - Our Environment

Question 1.

Which of the following groups contain only biodegradable items?

  • Grass, flowers and leather
  • Grass, wood and plastic
  • Fruit-peels, cake and lime-juice
  • Cake, wood and grass

Answer.

Fruit-peels, cake, lime juice, grass and wood are biodegradable substances. Hence, the answer is (c) and (d).

 

 

Question 2.

Which of the following constitute a food chain?

  • Grass, wheat and mango
  • Grass, goat and human
  • Goat, cow and elephant
  • Grass, fish and goat

Answer.

Grass, goat and human constitute a food chain. Hence, the answer is (b).

 

 

Question 3.

Which of the following are environment-friendly practices?

  • Carrying cloth-bags to put purchases in while shopping
  • Switching off unnecessary lights and fans
  • Walking to school instead of getting your mother to drop you on her scooter
  • All of the above

 

 

Answer.

All the above practices are environment-friendly since they reduce pressure on the environment and keep our environment clean.

Hence, answer is (d).

 

 

Question 4.

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

Answer.

Let us consider a food chain, Grass  --à  Deer  --à  Lion.

If all the lions (carnivore) are removed from the food chain, then deer (herbivore) population will increase.

This will lead to overgrazing, overgrazing in turn leads to soil erosion and deforestation.

This can cause change in climate and convert fertile land into barren land.

Hence, all the organisms of a food chain are of equal importance, killing a single organism can disturb the ecosystem.

 

 

Question 5.

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?

Answer.

The impact of removing all the organisms in a trophic level will have different effects on different trophic levels.

Let us take an example of a food chain:

Grass  --à Grasshopper --à  Frog --à Snake --à Eagle

If grass (producer) is removed from the food chain, all the herbivores will die and hence carnivores will also die due to lack of food.

If grasshoppers are removed from the food chain, then there will be massive growth of grass and no food for frog to eat.

Hence, later food chain will also suffer.

Hence, every trophic level has different impact of removing an organism from food chain.

If we remove any organism from any trophic level, there will be serious consequences to the ecosystem.

 

 

Question 6.

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

Answer.

Biological magnification or biomagnifications is defined as the accumulation or increase in the concentration of a toxic substance at each trophic level.

The concentration of this substance will be different at each trophic level.

It is said to be maximum at the highest trophic level (that is top carnivores).

 

 

Question 7.

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

Answer.

Non- biodegradable wastes are those which cannot be broken down into simpler forms by natural decomposers and hence causes various problems.

The problems caused by non-biodegradable wastes are as follows:

  • Increase in pollution.
  • Persist in environment for long time.
  • Makes soil infertile and reduces crop yield.
  • Causes various diseases in living organisms.
  • Causes biomagnifications.
  • Harmful gases are produced if we try to burn these wastes.

 

 

Question 8.

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

Answer.

If only biodegradable waste is generated, it will also have some negative impact on the environment.

  • As number of decomposers will be less, so wastes cannot be broken down into harmless substances in time.
  • This can be a breeding place for many disease causing organisms.
  • The obnoxious smell produced during decomposition can make the life of people miserable.
  • Gases released during decomposition can cause global warming.

Hence, we should focus on reducing waste.

 

 

Question 9.

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

Answer.

The damage to ozone layer has serious effects on environment and our health.

  • It causes skin cancer, ageing, skin darkening and cataracts in humans.
  • It also damages human immune system.
  • It can lead to death of phytoplanktons which can lead to global warming.
  • This can lead to disturbance in ecosystem.

There should be less release of CFCs into the atmosphere.

CFCs used in fire extinguishers and refrigerators should be replaced with environment-friendly substances.

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