Class 10 Science Chapter 13 Our Environment

1. What is an ecosystem composed of?

(A) Only plants and animals

(B) Only physical surroundings

(D) Only microorganisms

Answer

Answer: (C) Both biotic and abiotic components

2. Which of the following is an example of a human-made ecosystem?

(A) Forest

(B) Pond

(D) Lake

Answer

Answer: (C) Aquarium

3. Which organisms are known as producers in an ecosystem?

(A) Herbivores

(B) Carnivores

(D) Decomposers

Answer

Answer: (C) Green plants and certain bacteria

4. Which of the following is NOT a component of an ecosystem?

(A) Temperature

(B) Soil

(D) None of the above

Answer

Answer: (D) None of the above

5. What role do decomposers play in an ecosystem?

(A) They produce food

(B) They break down dead organisms and recycle nutrients

(D) They provide shelter for herbivores

Answer

Answer: (B) They break down dead organisms and recycle nutrients

6. What is the primary function of producers in an ecosystem?

(A) Breaking down organic matter

(B) Converting solar energy into chemical energy

(D) Providing oxygen to decomposers

Answer

Answer: (B) Converting solar energy into chemical energy

7. Which of the following is an example of a natural ecosystem?

(A) Garden

(B) Crop-field

(D) Aquarium

Answer

Answer: (C) Pond

8. Which organisms are responsible for decomposing dead organic matter?

(A) Producers

(B) Consumers

(D) Herbivores

Answer

Answer: (C) Decomposers

9. What type of ecosystem is a garden?

(A) Natural ecosystem

(B) Artificial ecosystem

(D) Grassland ecosystem

Answer

Answer: (B) Artificial ecosystem

10. Why do we need to clean an aquarium regularly?

(A) Because it lacks natural decomposers

(B) Because fish do not produce waste

(D) Because water is constantly replaced

Answer

Answer: (A) Because it lacks natural decomposers

11. Which of the following is the first trophic level in a food chain?

(A) Primary consumers

(B) Producers

(D) Tertiary consumers

Answer

Answer: (B) Producers

12. What percentage of solar energy is captured by green plants in a terrestrial ecosystem?

(A) 10%

(B) 5%

(D) 20%

Answer

Answer: (C) 1%

13. Why do food chains generally have only three to four steps?

(A) Energy is lost at each trophic level

(B) Higher-level consumers cannot digest plants

(D) Only herbivores exist in nature

Answer

Answer: (A) Energy is lost at each trophic level

14. What happens to the energy that is not transferred to the next trophic level?

(A) It is converted into minerals

(B) It is recycled back to producers

(D) It is absorbed by decomposers

Answer

Answer: (C) It is lost as heat

15. Which of the following correctly represents the flow of energy in a food chain?

(A) Producers → Primary consumers → Secondary consumers → Tertiary consumers

(B) Tertiary consumers → Secondary consumers → Primary consumers → Producers

(D) Producers → Decomposers → Consumers

Answer

Answer: (A) Producers → Primary consumers → Secondary consumers → Tertiary consumers

16. What is the role of decomposers in an ecosystem?

(A) They convert solar energy into food

(B) They break down organic matter into simpler substances

(D) They prevent energy loss in food chains

Answer

Answer: (B) They break down organic matter into simpler substances

17. Which of the following statements about energy flow in an ecosystem is correct?

(A) Energy flows in a circular path

(B) Energy flow is unidirectional

(D) Energy at higher trophic levels is greater than at lower levels

Answer

Answer: (B) Energy flow is unidirectional

18. What percentage of energy is typically transferred from one trophic level to the next?

(A) 50%

(B) 25%

(D) 1%

Answer

Answer: (C) 10%

19. Why are there usually more producers than consumers in an ecosystem?

(A) Because producers need more energy

(B) Because energy is lost at each trophic level

(D) Because decomposers rely on producers

Answer

Answer: (B) Because energy is lost at each trophic level

20. Which of the following best describes a food web?

(A) A straight-line sequence of who eats whom

(B) A simple relationship between producers and consumers

(D) A cycle where energy returns to the Sun

Answer

Answer: (C) A complex network of interconnected food chains

21. Why is energy flow in an ecosystem considered unidirectional?

(A) Because energy returns to the Sun

(B) Because energy lost as heat cannot be reused

(D) Because energy is stored indefinitely at each trophic level

Answer

Answer: (B) Because energy lost as heat cannot be reused

22. What happens to harmful chemicals like pesticides as they move up the food chain?

(A) They become less concentrated

(B) They disappear completely

(D) They get converted into useful nutrients

Answer

Answer: (C) They accumulate in higher concentrations

23. What is the process of accumulation of harmful chemicals at higher trophic levels called?

(A) Eutrophication

(B) Biological Magnification

(D) Decomposition

Answer

Answer: (B) Biological Magnification

24. Why do humans have the highest concentration of toxic substances in the food chain?

(A) Because humans consume food from multiple trophic levels

(B) Because humans are primary producers

(D) Because humans only consume decomposers

Answer

Answer: (A) Because humans consume food from multiple trophic levels

25. Which of the following is a consequence of biological magnification?

(A) Increased energy availability at higher trophic levels

(B) Increased population of producers

(D) Reduction of carbon dioxide in the atmosphere

Answer

Answer: (C) Harmful effects on top consumers like humans

26. What is the main function of the ozone layer in Earth’s atmosphere?

(A) To provide oxygen to living organisms

(B) To block harmful ultraviolet (UV) radiation

(D) To regulate Earth’s temperature

Answer

Answer: (B) To block harmful ultraviolet (UV) radiation

27. Which harmful chemicals are responsible for the depletion of the ozone layer?

(A) Carbon dioxide and methane

(B) Sulfur dioxide and nitrogen oxides

(D) Hydrocarbons and lead compounds

Answer

Answer: (C) Chlorofluorocarbons (CFCs)

28. What harmful effect does UV radiation have on humans?

(A) Increases oxygen levels

(B) Causes skin cancer and cataracts

(D) Improves immune function

Answer

Answer: (B) Causes skin cancer and cataracts

29. What was the international agreement signed to reduce CFC production?

(A) Kyoto Protocol

(B) Paris Agreement

(D) Rio Summit

Answer

Answer: (C) Montreal Protocol

30. How does ozone depletion affect the environment?

(A) Increases agricultural productivity

(B) Leads to global cooling

(D) Reduces greenhouse gases

Answer

Answer: (C) Harms aquatic ecosystems and disrupts food chains

31. What is the primary cause of ozone layer depletion?

(A) Increase in carbon dioxide emissions

(B) Excessive use of plastic

(D) Deforestation

Answer

Answer: (C) Release of chlorofluorocarbons (CFCs)

32. Which international body took action to control CFC emissions?

(A) World Health Organization (WHO)

(B) United Nations Environment Programme (UNEP)

(D) International Monetary Fund (IMF)

Answer

Answer: (B) United Nations Environment Programme (UNEP)

33. Why is ozone depletion a global concern?

(A) It reduces the amount of oxygen available

(B) It increases the amount of greenhouse gases

(D) It causes acid rain

Answer

Answer: (C) It allows more UV radiation to reach Earth’s surface

34. Which of the following human activities does NOT contribute to ozone depletion?

(A) Use of air conditioners and refrigerators with CFCs

(B) Industrial emissions containing CFCs

(D) Using aerosol sprays with CFCs

Answer

Answer: (C) Burning fossil fuels

35. What was the primary goal of the Montreal Protocol?

(A) To reduce carbon dioxide emissions

(B) To phase out the production of ozone-depleting substances

(D) To increase renewable energy use

Answer

Answer: (B) To phase out the production of ozone-depleting substances

36. What is the primary reason for managing waste disposal effectively?

(A) To increase landfill sites

(B) To reduce environmental pollution

(D) To increase waste production

Answer

Answer: (B) To reduce environmental pollution

37. Which of the following materials is biodegradable?

(A) Plastic

(B) Glass

(D) Metal

Answer

Answer: (C) Paper

38. What is the main problem caused by non-biodegradable waste?

(A) It decomposes too quickly

(B) It harms ecosystems and accumulates in the environment

(D) It improves air quality

Answer

Answer: (B) It harms ecosystems and accumulates in the environment

39. Which of the following is an environment-friendly waste management practice?

(A) Burning plastic waste

(B) Dumping waste in rivers

(D) Throwing garbage on roads

Answer

Answer: (C) Recycling and composting

40. Why are plastics considered harmful to the environment?

(A) They decompose easily

(B) They are biodegradable

(D) They improve soil fertility

Answer

Answer: (C) They persist in the environment for a long time

41. What is the main reason for the accumulation of non-biodegradable waste in the environment?

(A) It decomposes quickly

(B) It cannot be broken down by natural processes

(D) It is consumed by decomposers

Answer

Answer: (B) It cannot be broken down by natural processes

42. Which of the following is an example of non-biodegradable waste?

(A) Vegetable peels

(B) Paper

(D) Fruit peels

Answer

Answer: (C) Plastic bags

43. Why is improper waste disposal a serious environmental concern?

(A) It leads to land, air, and water pollution

(B) It improves the quality of soil

(D) It helps in the natural decomposition process

Answer

Answer: (A) It leads to land, air, and water pollution

44. Which of the following methods can help reduce non-biodegradable waste?

(A) Using plastic bags

(B) Burning plastic in open areas

(D) Dumping waste in rivers

Answer

Answer: (C) Recycling and reusing materials

45. Why is it important to separate biodegradable and non-biodegradable waste?

(A) To make waste collection more difficult

(B) To ensure that all waste is dumped together

(D) To reduce the amount of biodegradable waste

Answer

Answer: (C) To facilitate proper waste management and recycling

46. What is the primary cause of ozone depletion?

(A) Excessive use of fossil fuels

(B) Release of chlorofluorocarbons (CFCs)

(D) Industrial waste dumping

Answer

Answer: (B) Release of chlorofluorocarbons (CFCs)

47. Which of the following is an example of a biodegradable waste material?

(A) Plastic bottles

(B) Glass containers

(D) Metal cans

Answer

Answer: (C) Vegetable peels

48. What is the impact of excessive non-biodegradable waste on the environment?

(A) It helps in soil fertility

(B) It remains in the environment for a long time and causes pollution

(D) It increases oxygen levels

Answer

Answer: (B) It remains in the environment for a long time and causes pollution

49. What is an effective way to manage biodegradable waste?

(A) Burning it in open fields

(B) Dumping it into rivers

(D) Throwing it in plastic bags

Answer

Answer: (C) Composting it for organic manure

50. Why is it necessary to reduce the use of plastics?

(A) Because plastics decompose quickly

(B) Because plastics are biodegradable

(D) Because plastics help in soil conservation

Answer

Answer: (C) Because plastics persist in the environment and cause pollution