8A) Environment Ecology (Prelims PYQs)

Last Updated on November 5, 2025 by Admin

2025 Prelims PYQs

1] With reference to the planet Earth, consider the following statements: [2025/A-40]

I. Rain forests produce more oxygen than that produced by oceans.
II. Marine phytoplankton and photosynthetic bacteria produce about 50% of world’s oxygen.
III. Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air.
Which of the statements given above is/are correct?

a) I and II
b) II only
c) I and III
d) None of the above statements is correct

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Ans: b) II only

2024 Prelims PYQs

1] Consider the following: [2024]

1. Carabid beetles
2. Centipedes
3. Flies
4. Termites
5. Wasps

Parasitoid species are found in how many of the above kind of organisms?
a) Only two
b) Only three
c) Only four
d) All five

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Ans: b) Only three

2] Consider the following plants: [2024]

1. Groundnut
2. Horse-gram
3. Soybean

How many of the above belong to the pea family?
a)Only one
b)Only two
c)All three
d)None

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Ans: c) All three

3] The organisms “Cicada, Froghopper and Pond skater” are: [2024]

a) Birds
b) Fish
c) Insects
d) Reptiles

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Ans: c) Insects

4] Consider the following pairs: [2024]

Country – Animal round in its natural habitat
1. Brazil – Indri
2. Indonesia – Elk
3. Madagascar -Bonobo

How many of the pairs given above are correctly matched?
a) Only one
b) Only two
c) All three
d) None

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Ans: d) None

5] Consider the following statements: [2024]

1. Lions do not have a particular breeding season
2. Unlike most other big cats, cheetahs do not roar
3. Unlike male lions, male leopards do not proclaim their territory by scent marking

Which of the statements given above are correct?
a) 1 and 2 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2 and 3

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Ans: a) 1 and 2 only

6] Which one of the following shows a unique relationship with an insect that has co-evolved with it and that is the only insect that can pollinate this tree? [2024]

a) Fig
b) Mahua
c) Sandalwood
d) Silk cotton

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Ans: a) Fig

7] Consider the following: [2024]

1. Butterflies
2. Fish
3. Frogs

How many of the above have poisonous species among them?
a) Only one
b) Only two
c) All three
d) None

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Ans: c) All three

2023 Prelims PYQs

1] Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food? [2023]

a) Butterflies                         b) Dragonflies
c) Honeybees                        d) Wasps

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Ans: c) Honeybees

2] Which of the following makes a tool with a stick to scrape insects from a hole in a tree or a log of wood? [2023]

a) Fishing cat                        b) Orangutan
c) Otter                                     d) Sloth bear

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Ans: b) Orangutan

3] Consider the following statements: [2023]

1. Some mushrooms have medicinal properties.
2. Some mushrooms have psycho-active properties.
3. Some mushrooms have insecticidal properties.
4. Some mushrooms have bioluminescent properties.

How many of the above statements are correct?
a) Only one
b) Only two
c) Only three
d) All four

Show Answer

Ans: d) All four

2022 Prelims PYQs

1] “If rainforests and tropical’ forests are the lungs of the Earth, then surely. ‘wetlands function as its kidneys.” Which one of the following functions of wetlands best reflects the above statement? [2022]

a) The water cycle in wetlands involves surface runoff, subsoil percolation and evaporation.
b) Algae form the nutrient base upon which fish, crustaceans, molluscs, birds, reptiles and mammals thrive.
c) Wetlands play a vital role in maintaining sedimentation balance and soil stabilization..
d) Aquatic plants absorb heavy metals and excess nutrients.

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Ans: d) Aquatic plants absorb heavy metals and excess nutrients.

2021 Prelims PYQs

1] Consider the following kinds of organisms: [2021]

1) Copepods
2) Cyanobacteria
3) Diatoms
4) Foraminifera
Which of the above are primary producers in the food chains of oceans?

a) 1 and 2
b) 2 and 3
c) 3 and 4
d) 1 and 4

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Ans: b) 2 and 3

2] In case of which one of the following biogeochemical cycles the weathering of rocks is the main source of release of nutrient to enter the cycle? [2021]

a) Carbon cycle
b) Nitrogen cycle
c) Phosphorus cycle
d) Sulphur cycle

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Ans: c) Phosphorus cycle

3] Which of the following are detritivores? [2021]

1) Earthworms
2) Jellyfish
3) Millipedes
4) Seahorses
5) Woodlice
Select the correct answer using the code given below.

a) 1, 2 & 4 only
b) 2, 3, 4 & 5 only
c) 1, 3 & 5 only
d) 1, 2, 3, 4 & 5

Show Answer

Ans: c) 1, 3 & 5 only

4] Which of the following have species that can establish symbiotic relationship with other organisms? [2021]

1) Cnidarians
2) Fungi
3) Protozoa
Select the correct answer using the code given below.

a) 1 and 2 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2 and 3

Show Answer

Ans: d) 1, 2 and 3

2019 Prelims PYQs

1] Consider the following statements: [2019]

1. Some species of turtles are herbivores.
2. Some species of fish are herbivores.
3. Some species of marine mammals are herbivores.
4. Some species of snakes are viviparous.
Which of the statements given above is/are correct?

a) 1 and 3 only
b) 2, 3 and 4 only
c) 2 and 4 only
d) 1, 2, 3 and 4

Show Answer

Ans: d) 1, 2, 3 and 4

2018 Prelims PYQs

1] Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss? [2018]

1. Hard and waxy leaves
2. Tiny leaves
3. Thorns instead of leaves
Select the correct answer using the code given below:

a) 2 and 3 only
b) 2 only
c) 3 only
d) 1, 2 and 3

Show Answer

Ans: d) 1, 2 and 3

2017 Prelims PYQs

1] Due to some reasons, if there is a huge fall in the population of species of butterflies, what could be its likely consequence/consequences? [2017]

1. Pollination of some plants could be adversely affected.
2. There could be a drastic increase in the fungal infections of some cultivated plants.
3. It could lead to a fall in the population of some species of wasps, spiders and birds.
Select the correct answer using the code given below:

a) 1 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2 and 3

Show Answer

Ans: c) 1 and 3 only

2015 Prelims PYQs

1] Which one of the following is the best description of the term ‘ecosystem’? [2015]

a) A community of organisms interacting with one another
b) That part of the Earth which is inhabited by living organisms
c) A community of organisms together with the environment in which they live.
d) The flora and fauna of a geographical area.

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Ans: c) A community of organisms together with the environment in which they live.

2014 Prelims PYQs

1] Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of: [2014]

a) Algae and bacteria
b) Algae and fungi
c) Bacteria and fungi
d) Fungi and mosses

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Ans: b) Algae and fungi

2] Which one of the following is the correct sequence of a food chain? [2014]

a) Diatoms-Crustaceans-Herrings
b) Crustaceans-Diatoms-Herrings
c) Diatoms-Herrings-Crustaceans
d) Crustaceans-Herrings-Diatoms

Show Answer

Ans: a) Diatoms-Crustaceans-Herrings

3] Which of the following adds/ads carbon dioxide to the carbon cycle on the planet Earth? [2014]

1. Volcanic action
2. Respiration
3. Photosynthesis
4. Decay of organic matter
Select the correct answer using the code given below.

a) 1 and 3 only
b) 2 only
c) 1, 2 and 4 only
d) 1, 2, 3 and 4

Show Answer

Ans: c) 1, 2 and 4 only

2013 Prelims PYQs

1] Which of the following leaf modifications occurs/occur in desert areas to inhibit water loss? [2013]

1. Hard and waxy leaves
2. Tiny leaves or no leaves
3. Thorns instead of leaves
Select the correct answer using the codes given below.

a) 1 and 2 only
b) 2 only
c) 1 and 3 only
d) 1, 2 and 3

Show Answer

Ans: d) 1, 2 and 3

2] With reference to food chains in ecosystems, consider the following statements: [2013]

1. A food chain illustrates the order in which a chain of organisms feed upon each other.
2. Food chains are found within the population of a species.
3. A food chain illustrates the numbers of each organism which are eaten by others.
Which of the statements given above is/are correct?

a) 1 only
b) 1 and 2 only
c) 1, 2 and 3
d) None

Show Answer

Ans: a) 1 only

3] Which of the following adds/ adds nitrogen to the soil? [2013]

1. Excretion of Urea by animals
2. Burning of coal by man
3. Death of vegetation
Select the correct answer using the codes given below.

a) 1 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2, and 3

Show Answer

Ans: c) 1 and 3 only

4] Which one of the following terms describes not only the physical space occupied by an organism, but also its functional role in the community of organisms? [2013]

a) Ecotone
b) Ecological niche
c) Habitat
d) Home range

Show Answer

b) Ecological niche

5] In the grasslands, trees do not replace the grasses as a part of an ecological succession because of___? [2013]

a) Insects and fungi
b) Limited sunlight and paucity of nutrients
c) Water limits and fire
d) None of the above

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Ans: c) Water limits and fire

6] Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity? [2013]

a) Oceans, lakes, grasslands, mangroves
b) Mangroves, oceans, grasslands, lakes
c) Mangroves, grasslands, lakes, oceans
d) Oceans, mangroves, lakes, grasslands

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Ans: c) Mangroves, grasslands, lakes, oceans

7] With reference to the food chains in Ecosystems which of the following kinds of organism, is/are known as decomposer organism/ organisms? [2013]
1. Virus
2. Fungi
3. Bacteria
Select the correct answer using the codes given below.

a) 1 only
b) 2 and 3 only
c) 1 and 3 only
d) 1, 2 and 3

Show Answer

Ans: b) 2 and 3 only

2012 Prelims PYQs

1] Consider the following kinds of organisms: [2012]

1. Bat
2. Bee
3. Bird

Which of the above is/ an pollinating agent/agents?
a) 1 & 2 only                           b) 2 Only
c) 1 and 3 only                      d) 1, 2 & 3

Show Answer

Ans: d) 1, 2 & 3

2] The Millennium Ecosystem Assessment describes the following major categories of ecosystem services-provisioning, supporting, regulating, preserving and cultural.: [2012]

Which one of the following is supporting service?
a) Production of food and water
b) Control of climate and disease
c) Nutrient cycling and crop pollination
d) Maintenance of diversity

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Ans: c) Nutrient cycling and crop pollination

2011 Prelims PYQs

1] Consider the following: [2011]

1. Photosynthesis.
2. Respiration.
3. Decay of organic matter.
4. Volcanic action.

Which of the above add carbon dioxide to the carbon cycle on earth?
a) 1 and 4 only                      b) 2 and  3 only 
c) 2, 3 and 4 only                 d) 1,2,3 and 4

Show Answer

Ans: c) 2, 3 and 4 only  

2] In the context of ecosystem productivity, marine upwelling zones are important as they increase the marine productivity by bringing the ? [2011]

1. Decomposer microorganisms to the surface.
2. Nutrients to the surface.
3. Bottom-dwelling organisms to the surface.

Which of the statements given above is/are correct?
a) 1 and 2               b) 2 only
c) 2 and 3               d) 3 only

Show Answer

Ans: b) 2 only

3] If a tropical rain forest is removed, it does not regenerate quickly as compared to a tropical deciduous forest. This is because? [2011]

a) The soil of rain forest is deficient in nutrients.
b) Propagules of the trees in a rain forest have poor viability.
c) The rain forest species are slow-growing.
d) Exotic species invade the fertile soil of rain forest.

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Ans: a) The soil of rain forest is deficient in nutrients.

2010-1998 Prelims PYQs

1] A pesticide which is a chlorinated hydrocarbon is sprayed on a food crop. The food chain is: Food crop – Rat – Snake – Hawk. In this food chain, the highest concentration of the pesticide would accumulate in which one of the following? [2010]

a) Food crop                          b) Rat
c) Snake                                   d) Hawk

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Ans: d) Hawk

2] Some species of plants are insectivorous. Why? [2010]

a) Their growth in shady and dark places does not allow them to undertake sufficient  photosynthesis and thus they depend on insects for nutrition.
b) They are adapted to grow in nitrogen deficient soils and thus depend on insects for sufficient nitrogenous nutrition.
c) They can not synthesize certain vitamins themselves and depend on the insects digested by them.
d) They have remained in that particular stage of evolution as living fossils, a link between autotrophs and heterotrophs.

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Ans: b) They are adapted to grow in nitrogen deficient soils and thus depend on insects for sufficient nitrogenous nutrition.

3] Within biological communities, some species are important in determining the ability of a large number of other species to persist in the community. Such species are called: [2000]

a) Keystone species
b) Allopatric species
c) Sympatric species
d) Threatened species

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Ans: a) Keystone species

4] Estuaries possess distinct blooms of excessive growth of a pigmented dinoflagellates. These blooms are called: [1998]

a) Red tides                            b) Sea tides
c) Black tides                        d) Sea flowers

Show Answer

Ans: a) Red tides