CBSE Class 10 Science Our Environment Sure Shot Questions A

CBSE Class 10 Science Chapter 15 Our Environment Multiple Choice Questions 

Question. Which of the following is an abiotic component of an ecosystem?
(a) Bacteria
(b) Plants
(c) Fungi
(d) Humus
Answer. D

Question. Which of the following belongs to the category of primary consumers?
(a) Eagle and snake
(b) Grasshopper and cattle
(c) Snake and frog
(d) Water beetle and fish
Answer. B

Question. Food web helps in
(a) providing alternative pathways of food availability
(b) checking the overpopulation
(c) ecosystem stability
(d) all of these.
Answer. D

Question. As it travels along the food chains, the concentration of DDT
(a) increases
(b) remains constant
(c) decreases
(d) fluctuates randomly.
Answer. A

Question. Shorter food chains provide
(a) more energy
(b) less energy
(c) same energy
(d) any of these.
Answer. A

Question. In a grazing food chain, primary consumers (herbivores) represent
(a) T₁ level
(b) T₂ level
(c) T₃ level
(d) T₄ level.
Answer. B

Question. Which of the following does not help in protecting our environment?
(a) Crop rotation
(b) Treatment of sewage
(c) Deforestation
(d) Judicious use of fertilisers
Answer. C

Question. Now-a-days, which type of cups are being generally used in trains for serving tea/coffee/ soup etc. on daily basis?
(a) Washable glass cups
(b) Washable plastic cups
(c) Disposable paper cups
(d) Disposable cups made of plastic
Answer. C

Question.Green house gas produced by incomplete decomposition by anaerobic methanogens is
(a) CH₄
(b) CFCs
(c) CO₂
(d) N₂O
Answer. C

Question. Of the total amount of energy that passes from one trophic level to another in a food chain, about 10% is
(a) transpired
(b) burnt in respiration
(c) stored in body tissues
(d) lost as heat.
Answer. A

Question. If there was no CO₂ in the atmosphere, the earth’s temperature would be
(a) less than the present temperature
(b) same as the present temperature
(c) higher than the present temperature
(d) dependent on O₂ content of air.
Answer. A

Question. In the following groups of materials, which group(s) contains only non biodegradable items?
I. Wood, paper, leather
II. Polythene, detergent, PVC
III. Plastic, detergent, grass
IV. Plastic, bakelite, DDT
(a) III
(b) IV
(c) I and III
(d) II and IV
Answer. D

Question. Which group of organisms together do not constitute a food chain?
I . Grass, lion, rabbit, wolf
II. Plankton, man, hawk
III. Wolf, grass, snake, tiger
IV. Frog, snake, eagle, grass, grasshopper
(a) I and III
(b) III and IV
(c) II and III
(d) I and IV
Answer. C

Question. Fish that feeds on zooplanktons is a
(a) primary consumer
(b) secondary consumer
(c) tertiary consumer
(d) decomposer.
Answer. B

CBSE Class 10 Science Chapter 15 Our Environment Case Based Questions

Case I : Read the passage given below and answer the following questions.

Grazing food chains are directly dependent upon solar radiations as the primary source of energy. Green plants (or producers) form the first trophic level of the food chain. They synthesise their food by the process of photosynthesis. Herbivores or primary consumers feed upon the producers and form the second trophic level. Herbivores are eaten by carnivores of different categories. These are longer food chains.
Given below are 5 grazing food chains operating in the nature.

Question. Select the option that correctly identifies P,Q and R.
        P             Q                R
(a) Frog         Deer           Aquatic insect
(b) Frog         Elephant     Phytoplankton
(c) Tadpole     Deer          Zooplankton
(d) Dog         Elephant      Algae
Answer. A

Question. According to the given food chains which of the following animals is both secondary and tertiary consumer?
(a) Rabbit
(b) Tiger
(c) Eagle
(d) Small fish
Answer. B

Question. Top consumer in which of the following food chains will have the maximum energy?
(a) Food chain A
(b) Food chain B
(c) Food chain C
(d) Food chain D
Answer. A

Question. If energy present in producers of food chain D is 20,000 KJ. Then amount of energy present in its secondary consumer will be
(a) 2000 KJ
(b) 20 KJ
(c) 2 KJ
(d) 200 KJ.
Answer. D

Question. What will be the shape of pyramid of biomass of food chain E?

Answer. B

CBSE Class 10 Science Chapter 15 Our Environment Assertion And Reason Based MCQs

For question, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(a) Both assertion and reason are true, and reason is correct explanation of the assertion.
(b) Both assertion and reason are true, but reason is not the correct explanation of the assertion.
(c) Assertion is true, but reason is false.
(d) Assertion is false, but reason is true.

Question. Assertion : There is always an interaction between neighbouring or distant ecosystems.
Reason : An ecosystem is recognised as self - regulating and self - sustaining entity.
Answer. B

Question. Assertion : Pyramid of biomass may be upright or inverted.
Reason : Pyramid showing total biomass produced per unit time is always upright.
Answer. B

Question. Assertion : Man is a social and cultured animal.
Reason : He developed socio-cultural environment and lives in it.
Answer. A

Question. Assertion : Ozone depletion can be reduced by limiting the use of air conditioners and refrigerators.
Reason : Air conditioner and refrigerators release chlorofluorocarbons in the atmosphere that destroy ozone.
Answer. A

Question. Assertion : Paper cups are better option than plastic cups for serving tea.
Reason : Paper cups are biodegradable and can even be disposed off by burning.
Answer. A

CBSE Class 10 Science Chapter 15 Our Environment Very Short Answer Type Questions

Question. Name the radiations that are absorbed by ozone blanket.
Answer. Ultraviolet (UV) radiations

Question.Give reason why ozone layer in the stratosphere is considered useful?
Answer. Ozone layer in the stratosphere protects the living organisms including man from harmful UV radiations of the sun by absorbing most of them.

Question. Rearrange the given members of food chain in the correct trophic level: frog, grass, snake, insect.
Answer. Grass → Insect → Frog → Snake

Question. Why are green plants called ‘producers’?
Answer. Green plants are called ‘producers’ because they prepare their own food in the presence of sunlight and chlorophyll by the process of photosynthesis.

Question. Why are plastics non-biodegradable substances?
Answer. Plastics are non-biodegradable substance because they cannot be broken down by the action of enzymes, bacteria or decomposers.

CBSE Class 10 Science Chapter 15 Our Environment Short Answer Type Questions

Question. Differentiate between biodegradable and non-biodegradable substances.
Answer. Differences between biodegradable and nonbiodegradable substances are:

Question. Write two causes of depletion of ozone layer.
Answer. Two causes of depletion of ozone layer are :
(a) Use of CFCs (chlorofluorocarbons) in refrigerators and aerosol sprayers.
(b) Release of pollutant nitrogen monoxide by jets.

Question. Grass → Grasshopper → Frog → Snake → Eagle
In the above food chain, which of the organism will have
(i) maximum available energy?
(ii) minimum available energy?
Answer. (i) Grass will have the maximum available energy.
(ii) Eagle will have the minimum available energy.

Question. Producers always occupy the first trophic level in any food chain. Why?
Answer. Producers or green plants have chlorophyll which can trap the solar energy. The first trophic level in a food chain is a producer, i.e., those organisms which can produce food with the help of sunlight and chlorophyll by a process called photosynthesis.

Question. Why are microorganisms like bacteria and fungi important in the ecosystem?
Answer. Microorganisms like bacteria and fungi are important in the ecosystem because they decompose or break down the dead remains of animals and plants. This release the locked nutrients to be recycled in the ecosystem for reuse as raw materials by the producers.

Question. What is landfilling? How is it beneficial to the environment?
Answer. Landfilling is a method of waste disposal in which solid wastes from urban areas are dumped in low lying areas and compacted by rolling with bulldozers. They are then covered with a layer of soil.
Landfilling is an effective method of solid waste disposal in urban areas and at the same time, it helps in reducing the pollution arising out of the waste.

Question. Why proposal of use of kulhads (disposable cups made of clay) in trains was set aside?
Answer. Sometime back, use of kulhads (disposable cups made of clay) was suggested as an alternative of plastic cups.
However, making of kulhads on such a large scale would have resulted in the loss of top fertile soil. Therefore, this proposal was set aside.

Question. Stability of a biotic community in an ecosystem is inversely proportional to its diversity. Do you agree with this statement?
Answer. No, I do not agree with this statement. Stability of a biotic community is directly proportional to its diversity, number of species and their interactions. Larger the number of species within a community, more stable it will be.

Question. We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?
Answer. An aquarium is an artificial or man-made ecosystem and thus, is not self-regulatory whereas, ponds and lakes are natural, self-sustaining and complete ecosystems. Therefore, ponds and lakes get cleaned by natural processes but an aquarium needs to be cleaned.

Question. What does a trophic level represent in a food chain? State the position of autotrophs and herbivores in a food chain.
Answer. The various steps representing organisms in a food chain at which the transfer of food and energy takes place are called trophic levels.
The position of producers (or autotrophs) in a food chain constitute the first trophic level. They fix up sun’s energy and make it available for consumers. The herbivores or primary consumers (which feed upon plants) constitute the second trophic level in a food chain.

CBSE Class 10 Science Chapter 15 Our Environment Long Answer Type Questions

Question. “Energy flow in a food chain is unidirectional”. Justify this statement. Explain how the pesticides enter a food chain and subsequently get into our body.
Answer. The producers convert solar energy into chemical energy in the form of organic compounds. The primary consumers (herbivores) derive their nutrition from the producers. According to the energy transfer law, only 10% of energy is transferred from one trophic level to the other. So, the energy that is captured by the producers does not revert to the sun and the energy transferred to the herbivores does not come back to the producers. It just keeps on moving to the next trophic level in a unidirectional way. That is why the flow of energy in the food chain is always unidirectional. A large number of pesticides and chemicals are used to protect our crops from pests and diseases. Some of these chemicals are washed down from the soil, while some enter the water bodies. From the soil, they are absorbed by plants along with water and minerals; and from the water bodies, they are taken up by aquatic plants and animals. This is how these chemicals enter the food chain. As these chemicals cannot decompose, they accumulate progressively at each trophic level. This increase in the concentration of harmful chemicals with each step of the food chain is called biomagnification. As human beings occupy the top level in any food chain, these chemicals get accumulated in our bodies.

Question. Explain the phenomenon of ozone depletion.What are the factors responsible for it? What are its consequences?
Answer. Ozone depletion means the thinning of ozone layer in the atmosphere. Many chemicals mainly chlorofluorocarbons are responsible for ozone depletion. These are widely used as coolants in refrigerators and air conditioners; in fire extinguishers; in aerosol sprayer and as propellants. Once released in the air, these chemicals produce `active chlorine’ (Cl and ClO radicals) in the presence of UV radiations. These radicals, through chain reaction, then destroy the ozone by converting it into oxygen. A single active chlorine can deplete one lakh ozone molecules through chain reaction. Thinning of ozone layer allows ultraviolet (UV) radiations to pass through it which then strike the earth and cause harmful effects on man, animals and plants.
(i) UV radiations increase incidences of skin cancer and herpes.
(ii) UV radiations cause damage to eyes resulting in dimming of eye sight.
(iii) Cause damage to immune system hence, lowering the body’s resistance.
(iv) Harmful UV radiations increase mortality of developing embryo in the mothers, uterus.
(v) These radiations decline the rate of photosynthesis in plants which ultimately increase the CO2 concentration leading to global warming.

ASSIGNMENT QUESTIONS SET – 1

OUR ENVIRONMENT

1. What percentage of sunlight is captured by plants to convert it into food energy?

(a) 1%

(b) 10%

(c) 50%

(d) more than 50%

2. Flow of energy in an ecosystem is always

(a) unidrectional

(b) bidrectional

(c) multidirectional

(d) none of these

3. Which of the following is non-biodegradable?

(a) Tea leaves

(b) Nylon

(c) remains of animals

(d) fleece of sheep

4. The structural and functional unit of the environment is known as:

(a) ecosystem

(b) biosphere

(c) food chain

(d) food web

5. Depletion of ozone layer is mainly due to

(a) Methane

(b) Carbon Dioxide

(c) ChloroFloroCarbons

(d) Nitrogen

6. First order consumers are:

(a) Carnivores

(b) Herbivores

(c) Decomposers

(d) Omnivores 

7. A detritus food chain begins with

(a) Carnivores

(b) Herbivores

(c) Omnivores

(d) Decomposers

8. In an ecosystem, the 10% of energy disposable for transfer from one trophic lcvel to next is in the form of

(a) heat energy

(b) chemical energy

(c) mechanical energy

(d) light energy

9. Accumulation of non-biodegradable pesticides in the food chain in increasing amount at each higher trophic level is known as

(a) eutrophication

(b) pollution

(c) biomagnification

(d) accumulation

10. Which of the following is an abiotic component

(a) plants

(b) animals

(c) soil

(d) microorganisms

11. Which of the statement is incorrect?

(a) All green plants and blue green algae are producers

(b) Green plants get their food from organic compounds

(c) Producers prepare their own food from inorganic compounds

(d) Plants convert solar energy into chemical energy

12. Edaphic factors are included in

(a) Abiotic components

(b) Biotic components

(c) Producers

(d) Consumers

13. Only ____ % of the energy can be transferred from one trophic level to the next trophic level.

a) 1

b) 5

c) 10

d) 20

14. Accumulation of non- biodegradable pesticides in different trophic levels is called

a) Biological degradation

b) Biological magnification

c) Biological concentration

d) Biological deposition

15. The UV radiation from the sun is likely to cause _____________ in human.

a) Skin cancer

b) Lung cancer

c) Liver Cancer

d) Brain Cancer

16. World Environment day is celebrated on

a) July 1

b) July 5

c) June 1

d) June 5

17. Which one of the following is a non- biodegradable substance

a) DDT

b) Manure

c) paper

d) Cotton cloth

18. In a terrestrial ecosystem the biomass of ____________ should be the most

a) Herbivore

b) Carnivore

c) Producer

d) Any one of the above

19. Identify the proper food chain

a) Grass ----- frog ---- insect ----- snake

b) Grass---- insect ----- frog ------ snake

c) Insect --- frog ---- grass ---- snake

d) Grass --- frog ---- snake ----- insect

20. Food web is

a) Food served through websites

b) Display of different food items

c) Interlinked food chains

d) Using food items for a fashion dress

21. The best way to dispose waste is by

a) Making a paste of all domestic waste and putting them in a river

b) Separating biodegradable and nonbiodegradable waste before disposing in bins

c) Throw the waste on road side

d) Dumping all domestic waste in litter bin

22. Which of the following organism is likely to have maximum concentration of DDT : Algae, fish, water flea, frog, bird

23. What is the role of bacteria and fungi in an ecosystem?

24. What are trophic levels?

25. How much energy is transferred to the next trophic level in a food chain?

26. Which trophic level has the highest concentration of toxic substances in a food chain?

27. Mention some sources of CFC‘s.

28. Distinguish between a food chain & a food web

29. What would happen if there are no decomposers on earth?

30. What is a food chain? Write a five step food chain found in grass land with frog as one of the members. What will happen to organisms at different trophic levels if all the frogs are removed?

31. The number of malaria patients increased tremendously when a large number of frogs were exported from the village .What could be the cause for it? Explain with the help of a food chain.

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

33. Food chains generally consist of only 3 or 4 trophic levels. Why is it so?

34. Observe the food chain Plant (1000 kJ) --- >Goat ---> Lion (a) If autographs occupying the first trophic level are called producers what are herbivores Called as? (b) How much

energy does the lion get in the above food chain?

35. Vegetarian or non vegetarian food habit help us in getting more energy. Why?

36. How is ozone formed in the upper atmosphere? Why is the damage of ozone layer a cause of concern to us? State cause of this damage.

37. What is environment?

38. What happens when we add our waste to the environment or throw?

39. What are the different types of waste materials?

40. What happens after we throw waste away them away?

41. Why are some substances biodegradable and some non-biodegradable?

42. What are the harmful effects of biodegradable substance?

43. What are the harmful effects of non- biodegradable substance

44. Name some of the biodegradable plastics.

45. What are the differences between biodegradable and non-biodegradable wastes. What is Ecosystem? What are the different types of Ecosystem?

46. Why does aquarium have to be cleaned once in a while?

47. Do we have to clean ponds or lakes in the same manner of aquarium? Why or why not?

48. What are the different components of echo system?

49. What are trophic levels? Give an example of a food chain and state the different trophic levels in its.

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

51. What are the importances of decomposers?

52. What is a food chain?

53. What is food web?

54. Define the term ‘biome’.

55. What are the significances of food Chains?

56. How do flows of energy occur in tropic level?

57. What are the characteristics of energy transfer in the biosphere?

58. Why is energy flow considered as undirectional?

59. What is biomass?

60. Define biomagnifications.

61. How does a food web an important factor of our environment? Describe its four benefits.

62. What is 10% Law?

63. How much energy will be available to hawks in the food chain comprising hawk, snake, paddy and mice, if 1,000 J of energy is available to wheat plants from the sun?

64. Differentiate between food chain and food web?

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

66. Which compounds are responsible for the depletion of ozone layer?

67. Which disease is caused in human being due to depletion of ozone layer in the atmosphere?

68. Why is ozone layer getting depleted at higher levels of the atmosphere?

69. How is ozone formed in the upper atmosphere? Which compounds are responsible for the depletion of ozone layer?

70. When is World Ozone Layer Preservation Day celebrated?

71. What is green house effect?

72. Suggest activities in our daily life which are eco friendly.

73. How can you help in reducing the problem of waste disposal? Give any two methods.

74. What is the importance of phytoplankton?

75. Which pollutants are contributed by airplanes?

76. How is ozone layer formed in the atmosphere? What is the function of this layer?

77. Name any two biodegradable wastes.

78. Name any two non-biodegradable wastes.

79. Name two aquatic ecosystems.

80. Name two terrestial ecosystems.

81. Give two examples of Artificial ecosystems.

82. Which is the ultimate source of the energy for an ecosystem?

83. Name the category of organism which feed the energy into the ecosystems.

84. Give the scientific term for organisms which feed directly on plants.

85. How much of organic matter is available at each trophic level to reach the next level?

86. Name the type of organisms that occupy (i) the first trophic level and (ii) the second trophic level.

87. Define Biomagnification.

88. Expand UNEP.

89. Name the chemical mainly responsible for the damage of ozone layer.

90. Where are CFCs used?

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