Class 10 Science · Chapter 13

Our Environment

141 Class 10 Science questions on Our Environment from the NCERT textbook, NCERT Exemplar and CBSE board papers 2024–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 2 of 8

1. Q21 Exemplar · Multiple Choice Questions
   Accumulation ​of non-biodegradable ​pesticides in the ​food chain ​in increasing amount at ​each higher trophic ​level is ​known as

   1. (a)eutrophication
   2. (b)pollution
   3. (c)biomagnification
   4. (d)accumulation
   Show answer

   (c) biomagnification

   Step-by-step solution →
2. Q22 Exemplar · Multiple Choice Questions
   Depletion ​of ozone ​is mainly ​due ​to

   1. (a)chlorofluorocarbon compounds
   2. (b)carbon monoxide
   3. (c)methane
   4. (d)pesticides
   Show answer

   (a) chlorofluorocarbon compounds

   Step-by-step solution →
3. Q23 Exemplar · Multiple Choice Questions
   Organisms ​which synthesise ​carbohydrates from ​inorganic compounds ​using ​radiant energy are called

   1. (a)decomposers
   2. (b)producers
   3. (c)herbivores
   4. (d)carnivores
   Show answer

   (b) producers

   Step-by-step solution →
4. Q24 Exemplar · Multiple Choice Questions
   In ​an ecosystem, the ​10% of energy ​available for ​transfer from ​one trophic ​level ​to the next is in the form of

   1. (a)heat energy
   2. (b)light energy
   3. (c)chemical energy
   4. (d)mechanical energy
   Show answer

   (c) chemical energy

   Step-by-step solution →
5. Q25 Exemplar · Multiple Choice Questions
   Organisms ​of ​a higher ​trophic ​level which ​feed on several types of organisms belonging ​to a lower ​trophic level ​constitute the

   1. (a)food web
   2. (b)ecological pyramid
   3. (c)ecosystem
   4. (d)food chain
   Show answer

   (a) food web

   Step-by-step solution →
6. Q26 Exemplar · Multiple Choice Questions
   Flow ​of energy in ​an ecosystem ​is always

   1. (a)unidirectional
   2. (b)bidirectional
   3. (c)multi directional
   4. (d)no specific direction
   Show answer

   (a) unidirectional

   Step-by-step solution →
7. Q27 Exemplar · Multiple Choice Questions
   Excessive exposure ​of ​humans to U ​V-rays ​results in

   1. (i)damage to immune ​system
   2. (ii)​damage to lungs
   3. (iii)skin cancer
   4. (iv)peptic ulcers

   1. (a)(i) and (ii)
   2. (b)(ii) and (iv)
   3. (c)(i) and (iii)
   4. (d)(iii) and (iv)
   Show answer

   (c) (i) and (iii)

   Step-by-step solution →
8. Q28 Exemplar · Multiple Choice Questions
   In the following groups of materials, which group (s) ​contains ​only ​non-biodegradable items?

   1. (i)​Wood, ​paper, ​leather
   2. (ii)Polythene, detergent, PVC
   3. (iii)Plastic, detergent, ​grass
   4. (iv)Plastic, bakelite, DDT

   1. (a)(iii)
   2. (b)(iv)
   3. (c)(i) and (iii)
   4. (d)(ii) and (iv)
   Show answer

   (d) (ii) and (iv)

   Step-by-step solution →
9. Q29 Exemplar · Multiple Choice Questions
   Which of ​the following ​limits ​the number of ​trophic levels ​in a ​food ​chain?

   1. (a)Decrease in energy at higher trophic levels
   2. (b)Dufficient food supply
   3. (c)Polluted air
   4. (d)Water
   Show answer

   (a) Decrease in energy at higher trophic levels

   Step-by-step solution →
10. Q30 Exemplar · Multiple Choice Questions
    Which ​of the ​statement ​is incorrect?

    1. (a)All green plants and blue green algae are producers
    2. (b)Green plants get their food from organic compounds
    3. (c)Producers prepare their own food from inorganic compounds
    4. (d)Plants convert solar energy into chemical energy
    Show answer

    (b) Green plants get their food from organic compounds

    Step-by-step solution →
11. Q31 Exemplar · Multiple Choice Questions
    Which group of ​organisms ​are not constituents of a food chain?

    1. (i)Grass, lion, rabbit, wolf
    2. (ii)Plankton, man, fish, ​grasshopper
    3. (iii)Wolf, grass, snake, ​tiger
    4. (iv)​Frog, ​snake, eagle, ​grass, grasshopper

    1. (a)(i) and (iii)
    2. (b)(iii) and (iv)
    3. (c)(ii) and (iii)
    4. (d)(i) and (iv)
    Show answer

    (c) (ii) and (iii)

    Step-by-step solution →
12. Q32 Exemplar · Multiple Choice Questions
    The percentage of ​solar ​radiation ​absorbed by all the green plants ​for the ​process of ​photosynthesis ​is about

    1. (a)$1$ %
    2. (b)$5$ %
    3. (c)$8$ %
    4. (d)$10$ %
    Show answer

    (a) $1$ %

    Step-by-step solution →
13. Q33 Exemplar · Multiple Choice Questions
    In the ​given Figure 15.1 the ​various trophic levels are shown in ​a pyramid. ​At which trophic level is maximum ​energy ​available?

    1. (a)$T_4$
    2. (b)$T_2$
    3. (c)$T_1$
    4. (d)$T_3$
    Show answer

    (c) $T_1$

    Step-by-step solution →
14. Q34 Exemplar · Multiple Choice Questions
    What will ​happen if deer is ​missing ​in the food chain given ​below? Grass → ​Deer ​→ ​Tiger

    1. (a)The population of tiger increases
    2. (b)The population of grass decreases
    3. (c)Tiger will start eating grass
    4. (d)The population of tiger decreases and the population of grass increases
    Show answer

    (d) The population of tiger decreases and the population of grass increases

    Step-by-step solution →
15. Q35 Exemplar · Multiple Choice Questions
    The decomposers in an ecosystem

    1. (a)convert inorganic material, to simpler forms
    2. (b)convert organic material to inorganic forms
    3. (c)convert inorganic materials into organic compounds
    4. (d)do not breakdown organic compounds
    Show answer

    (b) convert organic material to inorganic forms

    Step-by-step solution →
16. Q36 Exemplar · Multiple Choice Questions
    If ​a grass hopper is ​eaten ​by ​a ​frog, then the energy transfer will be from

    1. (a)producer to decomposer
    2. (b)producer to primary consumer
    3. (c)primary consumer to secondary consumer
    4. (d)secondary consumer to primary consumer
    Show answer

    (c) primary consumer to secondary consumer

    Step-by-step solution →
17. Q37 Exemplar · Multiple Choice Questions
    Disposable ​plastic ​plates should ​not ​be ​used because

    1. (a)they are made of materials with light weight
    2. (b)they are made of toxic materials
    3. (c)they are made of biodegradable materials
    4. (d)they are made of non-biodegradable materials
    Show answer

    (d) they are made of non-biodegradable materials

    Step-by-step solution →
18. Q38 Exemplar · Short Answer Questions
    Why ​is ​improper disposal ​of waste a ​curse ​to environment?
    Show answer

    Improper disposal spoils land, pollutes water and air and spreads disease, while useful compost and recyclable material is wasted.

    Waste thrown away carelessly is never really removed, so it goes on damaging the surroundings. (i) Land: the non-biodegradable part — plastic, glass, metal, e-waste — stays for decades, dumps occupy and spoil land, and cattle die after swallowing polythene. (ii) Water: rain soaking through a dump carries nitrates and toxic metals down into the groundwater, and nitrate and phosphate washed into ponds cause eutrophication, whose decaying algal bloom uses up the dissolved oxygen and kills the fish. (iii) Air: open burning of waste gives smoke, carbon monoxide and toxic gases, and rotting heaps give off methane and a foul smell. (iv) Health: flies, mosquitoes and rats breed on the heaps and spread cholera, dysentery, dengue and malaria. In addition, material that could have become compost or a recycled article is lost. Because a single badly-managed heap harms land, water, air and people all at once, improper disposal is a curse to the environment; the same waste, segregated at source, composted and recycled, is a resource.

    Step-by-step solution →
19. Q39 Exemplar · Short Answer Questions
    Write the common ​food chain ​of ​a pond ​ecosystem.
    Show answer

    Phytoplankton are eaten by zooplankton, then small fish, then large fish; decomposers return nutrients to the water.

    The common food chain of a pond ecosystem is: Phytoplankton (algae, diatoms) $\to$ Zooplankton $\to$ Small fish $\to$ Large fish. Here the phytoplankton are the producers ($T_1$), the zooplankton the primary consumers ($T_2$), the small fish the secondary consumers ($T_3$) and the large fish the tertiary consumers ($T_4$). If a fish-eating bird such as a kingfisher or crane, or a human being, feeds on the large fish, it forms one more level. Each arrow points from the organism eaten to the organism that eats it. Decomposers — bacteria and fungi — act on the dead remains of every level and return simple nutrients to the pond water, where the phytoplankton take them up again.

    Step-by-step solution →
20. Q40 Exemplar · Short Answer Questions
    What are the advantages ​of ​cloth bags ​over ​plastic ​bags ​during ​shopping?
    Show answer

    Cloth bags are renewable, strong, reusable and biodegradable, whereas plastic bags are non-biodegradable and choke drains and harm animals.

    Cloth bags are better than plastic carry bags because: (i) They are made of cotton or jute, natural fibres that are grown again each season, whereas polythene is made from petroleum, a non-renewable fossil fuel; (ii) Cloth is strong and carries a heavy load without tearing; (iii) A cloth bag can be washed and reused hundreds of times, so one of them replaces a great many plastic bags and far less waste is made in the first place; (iv) A worn-out cloth bag is biodegradable — decomposers break it down and the material returns to the soil — while a plastic bag is non-biodegradable and remains for hundreds of years; (v) Plastic bags choke drains and cause waterlogging, are swallowed by cattle and by marine animals and kill them, and give off toxic gases when burnt, and cloth bags do none of these. Carrying a cloth bag is therefore the simplest eco-friendly habit a shopper can adopt.

    Step-by-step solution →