Class 10, Science, Our Environment- MCQ based on NCERT book

13.1 ECO-SYSTEM — WHAT ARE ITS COMPONENTS?

1) What is an ecosystem?

a) A group of animals living together in an area

b) A system of interacting organisms and their physical environment

c) A collection of plants and microorganisms in a specific location

d) A controlled environment for scientific research

Answer: b) A system of interacting organisms and their physical environment

2) Which components form an ecosystem?

a) Living organisms only

b) Non-living factors only

c) Biotic and abiotic components

d) Human-made structures

Answer: c) Biotic and abiotic components

3) Which of the following is an example of an abiotic component in an ecosystem?

a) Animals

b) Plants

c) Rainfall

d) Microorganisms

Answer: c) Rainfall

4) What do biotic components in an ecosystem comprise?

a) Physical factors like temperature and wind

b) Living organisms such as plants and animals

c) Soil and minerals

d) Both b) and c)

Answer: b) Living organisms such as plants and animals

5) Which of the following statements about ecosystems is correct?

a) The various components of an ecosystem are independent of each other.

b) The various components of an ecosystem do not interact with each other.

c) The various components of an ecosystem are interdependent.

d) The various components of an ecosystem are not connected.

Answer: c) The various components of an ecosystem are interdependent.

6) What role do producers play in an ecosystem?

a) They consume energy from other organisms.

b) They make the energy from sunlight available to the rest of the ecosystem.

c) They break down non-biodegradable substances.

d) They directly consume primary consumers.

Answer: b) They make the energy from sunlight available to the rest of the ecosystem.

7) Why is maintaining a balance in nature important within an ecosystem?

a) To encourage human activities

b) To support the dominance of certain species

c) To ensure the overall health and functioning of the ecosystem

d) To create a controlled environment

Answer: c) To ensure the overall health and functioning of the ecosystem

8) Which type of interaction involves one organism preying on another for food?

a) Competition

b) Mutualism

c) Predation

d) Commensalism

Answer: c) Predation

9) Which of the following is an example of an abiotic factor influencing an ecosystem?

a) Competition between two animal species

b) A plant providing shelter for insects

c) Soil quality affecting plant growth

d) Microorganisms breaking down dead matter

Answer: c) Soil quality affecting plant growth

10) How do organisms interact with each other in an ecosystem?

a) Through temperature regulation

b) By exchanging gases

c) By engaging in physical activities

d) Through various processes like predation and competition

Answer: d) Through various processes like predation and competition

11) Which component of an ecosystem includes microorganisms and human beings?

a) Biotic components

b) Abiotic components

c) Rocks and Minerals

d) Non-living components

Answer: a) Biotic components

12) What do non-living constituents of an ecosystem comprise?

a) Animals and plants

b) Microorganisms and minerals

c) Biotic and abiotic factors

d) Physical factors like temperature and rainfall

Answer: d) Physical factors like temperature and rainfall

13) Which organisms can produce organic compounds like sugar and starch through photosynthesis?

a) Consumers

b) Decomposers

c) Herbivores

d) Producers

Answer: d) Producers

14) What is the role of producers in an ecosystem?

a) Breaking down organic substances

b) Feeding on other consumers

c) Providing sustenance to consumers

d) Decomposing dead organisms

Answer: c) Providing sustenance to consumers

15) Which type of consumer feeds on both plants and animals?

a) Herbivores

b) Carnivores

c) Omnivores

d) Parasites

Answer: c) Omnivores

16) Give an example of a carnivore.

a) Human

b) Cow

c) Lion

d) Rabbit

Answer: c) Lion

17) What role do decomposers play in the ecosystem?

a) Producing organic compounds through photosynthesis

b) Consuming food produced by producers

c) Breaking down dead organic matter into simple inorganic substances

d) Feeding on other consumers

Answer: c) Breaking down dead organic matter into simple inorganic substances

18) What happens to dead remains and waste products in the absence of decomposers?

a) They turn into producers

b) They become consumers

c) They accumulate and do not decompose

d) They turn into inorganic substances through photosynthesis

Answer: c) They accumulate and do not decompose

19) Which organisms obtain their sustenance by feeding directly on producers?

a) Herbivores

b) Carnivores

c) Omnivores

d) Parasites

Answer: a) Herbivores

20) Name an example of a herbivore.

a) Lion

b) Tiger

c) Deer

d) Hawk

Answer: c) Deer

21) What is the primary source of energy for producers to produce food?

a) Water

b) Air

c) Sunlight

d) Soil

Answer: c) Sunlight

22) In the absence of decomposers, what will happen to the natural replenishment of the soil?

a) It will increase

b) It will decrease

c) It will remain the same

d) It will stop

Answer: d) It will stop

13.1.1 Food Chains and Webs

23) What is the first trophic level in a food chain?

a) Herbivores

b) Primary consumers

c) Autotrophs (producers)

d) Decomposers

Answer: c) Autotrophs (producers)

24) What does the term "trophic level" refer to in a food chain?

a) The energy lost at each step

b) The number of consumers in an ecosystem

c) The flow of energy between organisms

d) Each step or level in the food chain

Answer: d) Each step or level in the food chain

25) How much energy do green plants capture from sunlight and convert into food energy?

a) 10%

b) 25%

c) 50%

d) 1%

Answer: d) 1%

26) What percentage of the food eaten by primary consumers is turned into its own body and made available for the next level of consumers?

a) 5%

b) 25%

c) 50%

d) 10%

Answer: d) 10%

27) Why do food chains generally consist of only three or four steps?

a) The environment can only support three or four trophic levels

b) The loss of energy at each step is minimal

c) The loss of energy at each step is significant, leaving little usable energy for the next level

d) Producers cannot support more than three or four consumers

Answer: c) The loss of energy at each step is significant, leaving little usable energy for the next level

28) What is the primary source of energy for the living world?

a) Heat energy

b) Sunlight

c) Digestive energy

d) Chemical energy

Answer: b) Sunlight

29) How is the relationship between organisms represented when an organism is eaten by multiple other kinds of organisms?

a) Food chain

b) Food web

c) Trophic level

d) Autotrophs

Answer: b) Food web

30) What percentage of organic matter reaches the next level of consumers in a food chain?

a) 1%

b) 10%

c) 25%

d) 50%

Answer: b) 10%

31) Which trophic level consists of the greatest number of individuals in an ecosystem?

a) Autotrophs

b) Primary consumers

c) Secondary consumers

d) Tertiary consumers

Answer: a) Autotrophs

32) What do we call the organisms that capture the energy present in sunlight and convert it into chemical energy?

a) Heterotrophs

b) Consumers

c) Decomposers

d) Autotrophs (producers)

Answer: d) Autotrophs (producers)

33) What does the energy flow diagram (Fig. 13.4) show regarding the flow of energy in an ecosystem?

a) Energy is reversible between trophic levels

b) Energy is unidirectional and flows back to the solar input

c) Energy captured by autotrophs is available to herbivores again

d) Energy diminishes progressively as it moves through trophic levels

Answer: d) Energy diminishes progressively as it moves through trophic levels

34) What is the term used to describe the process by which harmful chemicals enter the food chain and accumulate at each trophic level?

a) Biological magnification

b) Unidirectional energy flow

c) Energy regression

d) Trophic chemical absorption

Answer: a) Biological magnification

35) How do harmful chemicals like pesticides enter the food chain?

a) Through the soil and water bodies

b) Through the atmosphere

c) Through direct consumption by humans

d) Through the solar input

Answer: a) Through the soil and water bodies

36) Which organisms occupy the top level in any food chain and accumulate the highest concentration of harmful chemicals?

a) Autotrophs

b) Herbivores

c) micro-organisms

d) Human beings

Answer: d) Human beings

37) Why do harmful chemicals accumulate at each trophic level in the food chain?

a) Because they are reversible

b) Because they are degradable

c) Because they are absorbed by plants only

d) Because they are not degradable

Answer: d) Because they are not degradable

38) What causes the limitation of trophic levels in a food chain?

a) An increase in energy at each level

b) A decrease in energy at each level

c) The absence of producers

d) A stable environment

Answer: b) A decrease in energy at each level

39) What is the primary reason for the progressive diminishing of energy at each trophic level in a food chain?

a) The loss of energy at each level

b) The increasing number of trophic levels

c) The availability of solar energy

d) The flow of energy back to previous levels

Answer: a) The loss of energy at each level

40) What does the phenomenon of biological magnification imply in a food chain?

a) Harmful chemicals are washed away by water bodies

b) The concentration of harmful chemicals decreases at higher trophic levels

c) Human beings have the least concentration of harmful chemicals

d) Harmful chemicals accumulate at higher trophic levels, including human beings

Answer: d) Harmful chemicals accumulate at higher trophic levels, including human beings

41) How do pesticides and chemicals enter the bodies of human beings?

a) Through direct consumption only

b) Through the atmosphere

c) Through consumption of contaminated food from the food chain

d) Through absorption by autotrophs

Answer: c) Through consumption of contaminated food from the food chain

42) What is the flow of energy between trophic levels in a food chain?

a) Reversible and unidirectional

b) Reversible and bidirectional

c) Unidirectional

d) Bidirectional

Answer: c) Unidirectional

43) What happens to the energy that is captured by autotrophs and does not revert back to solar input?

a) It is lost as heat

b) It is transferred to primary consumers

c) It accumulates in autotrophs

d) It diminishes progressively as it moves through trophic levels

Answer: d) It diminishes progressively as it moves through trophic levels

 

13.2 HOW DO OUR ACTIVITIES AFFECT THE ENVIRONMENT?

13.2.1 Ozone Layer and How it is Getting Depleted

44) What is ozone (O3) composed of?

a) Two oxygen atoms (O2)

b) Three oxygen atoms (O3)

c) Three hydrogen atoms (H3)

d) Two hydrogen atoms (H2)

Answer: b) Three oxygen atoms (O3)

45) What essential function does ozone perform at the higher levels of the atmosphere?

a) Shielding the earth from visible light

b) Protecting organisms from infrared radiation

c) Protecting organisms from ultraviolet (UV) radiation

d) Generating oxygen for all aerobic forms of life

Answer: c) Protecting organisms from ultraviolet (UV) radiation

46) Why is UV radiation from the Sun highly damaging to organisms?

a) It causes skin cancer in human beings

b) It enhances photosynthesis in plants

c) It improves the immune system

d) It helps in the synthesis of ozone

Answer: a) It causes skin cancer in human beings

47) How is ozone formed in the higher levels of the atmosphere?

a) Through the combination of hydrogen and oxygen

b) Through the combination of ozone and UV radiation

c) Through the splitting of oxygen (O2) molecules by UV radiation

d) Through the combination of carbon and oxygen

Answer: c) Through the splitting of oxygen (O2) molecules by UV radiation

48) What has been linked to the sharp drop in the amount of ozone in the atmosphere?

a) Increasing levels of oxygen (O2)

b) Ultraviolet (UV) radiation

c) Chlorofluorocarbons (CFCs)

d) Higher levels of ozone (O3)

Answer: c) Chlorofluorocarbons (CFCs)

49) In which decade did the decrease in ozone levels begin to occur?

a) 1970s

b) 1980s

c) 1990s

d) 2000s

Answer: b) 1980s

50) What is the impact of CFCs on the ozone layer?

a) It strengthens the ozone layer

b) It causes an increase in ozone production

c) It depletes the ozone layer

d) It has no effect on the ozone layer

Answer: c) It depletes the ozone layer

51) What agreement was made by UNEP in 1987 to address the decrease in ozone levels?

a) Freeze the production of oxygen (O2)

b) Freeze the production of CFCs at 1986 levels

c) Increase the production of CFCs worldwide

d) Ban the use of refrigerants and fire extinguishers

Answer: b) Freeze the production of CFCs at 1986 levels

52) Why is it now mandatory for manufacturing companies to produce CFC-free refrigerators worldwide?

a) To enhance refrigeration efficiency

b) To decrease the cost of refrigerators

c) To reduce ozone depletion

d) To increase the use of CFCs

Answer: c) To reduce ozone depletion

53) What does UV radiation from the Sun do to oxygen (O2) molecules in the atmosphere?

a) It forms ozone (O3)

b) It enhances oxygen production

c) It strengthens the ozone layer

d) It has no effect on oxygen molecules

Answer: a) It forms ozone (O3)

54) How have chemicals like CFCs endangered the ozone layer?

a) CFCs have strengthened the ozone layer.

b) CFCs have no impact on the ozone layer.

c) CFCs have caused a decrease in ozone production.

d) CFCs have caused a depletion of the ozone layer, endangering the environment.

Answer: d) CFCs have caused a depletion of the ozone layer, endangering the environment.

13.2.2 Managing the Garbage we Produce

55) The food we eat is digested by various enzymes in our body. Why are enzymes specific in their action?

a) They break down everything we eat

b) They require heat and pressure to function

c) They are not affected by physical processes

d) Different enzymes are needed for the breakdown of different substances

Answer: d) Different enzymes are needed for the breakdown of different substances

56) What is the fate of human-made materials like plastics when thrown away?

a) They are broken down by enzymes

b) They persist for a long time in the environment

c) They are immediately biodegradable

d) They turn into harmless substances

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

57) Which substances are said to be biodegradable?

a) Non-biodegradable substances

b) Materials acted upon by physical processes

c) Substances broken down by biological processes

d) Inert substances

Answer: c) Substances broken down by biological processes

58) What is the term for substances that are not broken down by biological processes?

a) Inert substances

b) Biodegradable substances

c) Enzyme-specific substances

d) Non-biodegradable substances

Answer: d) Non-biodegradable substances

59) What impact do improvements in lifestyle and changes in attitudes have on waste generation?

a) Decreases waste material generation

b) Increases biodegradable waste

c) Decreases non-biodegradable waste

d) Increases waste material generation

Answer: d) Increases waste material generation

60) How do changes in packaging contribute to non-biodegradable waste?

a) They make materials more biodegradable

b) They promote the use of enzymes for breakdown

c) They result in more disposable items

d) They encourage biological processes for waste management

Answer: c) They result in more disposable items

61) What happens to non-biodegradable substances in the environment?

a) They are immediately broken down

b) They harm various members of the ecosystem

c) They turn into biodegradable substances

d) They become inert and harmless

Answer: b) They harm various members of the ecosystem

62) Which substances are not affected by physical processes and persist for a long time?

a) Non-biodegradable substances

b) Biodegradable substances

c) Enzyme-specific substances

d) Inert substances

Answer: a) Non-biodegradable substances

63) What term is used for substances that can be broken down by biological processes?

a) Inert

b) Non-biodegradable

c) Biodegradable

d) Disposables

Answer: c) Biodegradable

64) What impact do human activities have on the environment?

a) Human activities have no impact on the environment.

b) Human activities positively impact the environment.

c) Human activities negatively impact the environment.

d) Human activities only impact ecosystems.

Answer: c) Human activities negatively impact the environment.