Our environment Worksheet-13

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?

47. How is ozone layer useful to us?

48. What are biotic and abiotic components?

49. Define man-made ecosystem. Name two natural and two man-made ecosystem.

50. How do natural replenishment of soil take place?

51. Why food chain normally consists of 3 or 4 steps only?

52. Write a note on CFCs.

53. Garden is an ecosystem. Explain with an example.

54. Why segregation of waste is necessary?

55. Which radiations are absorbed by ozone layer? What are the causes of depletion of ozone layer? Which diseases are likely to be caused if ozone layer becomes thinner?

56. List the constituents of biotic environment.

57. Why are efforts being made to substitute the chemicals like chlorofluorocarbons and fluorocarbons?

58. What give rise to various environmental problems? How can these problems be visualised?

59. Why are some substances biodegradable and some non­biodegradable?

60. Give any two ways in which biodegradable substances would affect the environment.