Our environment Worksheet

Our environment Worksheet-13

41. How can biodegradable substances work as pollutants? Bring out the meaning of the term 'biodegradable'?

42. Give the full form of CFC. Name any three sources of CFC.

43. Explain why there are greater chances of accumulation of harmful chemicals in the body of human beings.

44. What is the importance of the ozone layer?

45. Name some of the damaging effects of the ultra-violet rays on the animal and plant life on earth.

46. What is meant by the depletion of ozone layer? How is it caused?

Our environment Worksheet-14

61. Give any two ways in which non-biodegradable substances would affect the environment.

62. What is the role of decomposers in the ecosystem?

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

64. 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?

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

Our environment Worksheet-15

1. With the help of examples discuss in brief the role of decomposers in cycling of materials.

2. Consider the following food chains:

(a) Plants  → Mice → Snakes → Hawks

(b) Plants → Mice → Hawks.

If energy available at the producer level in both the food chains is 100 J, in which case will Hawks get more energy as food and by what factor? Justify your answer.

3. Consider the following food chains :

Grass → Mice → Snakes → Peacocks.