UPSC Prelims Environment & Ecology PYQs: Basics Of Ecology And Related Concepts

The collection includes past years’ questions (PYQs) on Environment & Ecology from UPSC Prelims. It covers Basics of Ecology and Related Concepts such as ecological factors, adaptation of plants and animals, population ecology, community ecology, and ecosystems. For a broader understanding, check out UPSC Prelims PYQs: Climate Conferences & Summits.

Q. With reference to “water vapour”, which of the following statements is/are correct? (UPSC (Pre) 2024)

1. It is a gas, the amount of which decreases with altitude.
2. Its percentage is maximum at the poles.

Select the answer using the codes given below:

(a) 1 Only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Ans: (a)

Q. Consider the following description: UPSC (Pre) 2024

1. Annual and daily range of temperatures is low
2. Precipitation occurs throughout the year
3. Precipitation varies between 50 cm-250 cm

What is this type of climate?

(a) Equatorial climate
(b) China type climate
(c) Humid subtropical Climate
(d) Marine West coast climate

Ans: (d)

Q. Consider the following: [UPSC (Pre) 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

Ans: (b)

Q. Consider the following statements : UPSC (Pre) 2024

Statement-I : The Indian Flying Fox is placed under the “vermin” category in the Wild Life (Protection) Act, 1972.
Statement-II : The Indian Flying Fox feeds on the blood of other animals.

Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
(c) Statement-I is correct, but Statement-II is incorrect
(d) Statement-I is incorrect, but Statement-II is correct

Ans: (c)

Q. The Organisms “Cicada, Froghopper and Pond Skater” are : [UPSC (Pre) 2024]

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

Ans: (c)

Q. Consider the following pairs : UPSC (Pre) 2024

Country	Animal found in its natural habitat
Brazil	Indri
Indonesia	Elk
Madagascar	Bonobo

How many of the pairs given above are correctly matched?

(a) Only one
(b) Only two
(c) All three
(d) None

Ans: (d)

Q. Consider the following statements : [UPSC (Pre) 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

Ans: (a)

Q. Which one of the following shows a unique relationship with an insect that has coevolved with it and that is the only insect that can pollinate this tree? [UPSC (Pre) 2024]

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

Ans: (a)

Q. Consider the following : [UPSC (Pre) 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

Ans: (c)

Q. Consider the following : [UPSC (Pre) 2024]

1. Cashew
2. Papaya
3. Red sanders

How many of the above trees are actually native to India?

(a) Only one
(b) Only two
(c) All three
(d) None

Ans: (a)

Q. Consider the following statement: [UPSC (Pre) 2023]

Statement 1: Marsupials are not naturally found in India.
Statement 2: Marsupials can thrive only in montane grasslands with no predators.

Which one of the following is correct in respect of the above statements?

(a) Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.
(b) Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.
(c) Statement 1 is correct but Statement 2 is not correct.
(d) Statement 1 is not correct but Statement 2 is correct.

Ans: (c)

Q. Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to the source of their food? [UPSC (Pre) – 2023]

(a) Butterflies

(b) Dragonflies

(d) Wasps

Ans: (c)

Q. Consider the following statements: [UPSC (Pre) – 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

(d) All four

Ans: (d)

Q. Consider the following statements regarding the Indian squirrels: [UPSC (Pre) – 2023]

1. They build nests by making burrows in the ground.
2. They store their food materials like nuts and seeds in the ground.
3. They are omnivorous.

How many of the above statements are correct?

(a) Only one

(b) Only two

(d) None

Ans: (c)

Q. Consider the following statements: [UPSC (Pre) – 2023]

1. Some microorganisms can grow in environments with temperature above the boiling point of water.
2. Some microorganisms can grow in environments with temperature below the freezing point of water.
3. Some microorganisms can grow in highly acidic environments with pH below 3.

How many of the above statements are correct?

(a) Only one

(b) Only two

(d) None

Ans: (c)

Q. Which one of the following makes a tool with a stick to scrap insects from a hole in a tree or a log of wood? [UPSC (Pre) – 2023]

(a) Fishing cat

(b) Orangutan

(d) Sloth bear

Ans: (b)

Q. Which of the following are nitrogen-fixing plants? [UPSC (Pre) – 2022]

1. Alfalfa
2. Amaranth
3. Chickpea
4. Clover
5. Purslane (Kulfa)
6. Spinach

Select the correct answer using the code given below:

(a) 1, 3 and 4 only

(b) 1, 3, 5 and 6 only

(d) 1, 2, 4, 5 and 6

Ans: (a)

Q. Certain species of which one of the following organisms are well known as cultivators of fungi? [UPSC (Pre) – 2022]

(a) Ant

(b) Cockroach

(d) Spider

Ans: (a)

Q. 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? [UPSC (Pre) – 2021]

(a) Carbon cycle

(b) Nitrogen cycle

(d) Sulphur cycle

Ans: (c)

Q. Which of the following are detritivores? [UPSC (Pre) – 2021]

1. Earthworms
2. Jellyfish
3. Millipedes
4. Seahorses
5. Woodlice

Select the correct answer using the code given below:

(a) 1, 2 and 4 only

(b) 2, 3, 4 and 5 only

(d) 1, 2, 3, 4 and 5

Ans: (c)

Q. Which of the following have species that can establish a symbiotic relationship with other organisms? [UPSC (Pre) – 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

Answer: (d)

Q. In the nature, which of the following is/are most likely to be found surviving on a surface without soil? [UPSC (Pre) – 2021]

1. Fern
2. Lichen
3. Moss
4. Mushroom

Select the correct answer using the code given below:

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

Answer: (b)

Q. Consider the following kinds of organisms: [UPSC (Pre) – 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

Answer: (b)

Q. Consider the following animals: [UPSC (Pre) – 2021]

1. Hedgehog
2. Marmot
3. Pangolin

To reduce the chance of being captured by predators, which of the above organisms rolls up/roll up and protects/protect its/their vulnerable parts?

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

Answer: (d)

Q. Consider the following statements: [UPSC (Pre) – 2019]

1. Agricultural soils release nitrogen oxides into the environment.
2. Cattle release ammonia into the environment.
3. Poultry industry releases reactive nitrogen compounds into the environment.

Which of the statements given above is/are correct?

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

Answer: (d)

Q. Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss? [UPSC (Pre) – 2018]

1. Hard and waxy leaves
2. Tiny leaves
3. Thorns, instead of leaves

Select the correct answer using the codes given below:

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

Answer: (d)

Q. What can be the impact of excessive/inappropriate use of nitrogenous fertilizers in agriculture? [UPSC (Pre) – 2015]

1. Proliferation of nitrogen-fixing microorganisms in soil can occur.
2. Increase in the acidity of soil can take place.
3. Leaching of nitrate to the groundwater can occur.

Select the correct answer using the codes given below:

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

Answer: (c)

Q. Which one of the following is the best description of the term “ecosystem”? [UPSC (Pre) – 2015]

(a) A community of organisms interacting with one another
(b) 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

Answer: (c)

Q. Which of the following add(s) carbon dioxide to the carbon cycle on the planet earth? [UPSC (Pre) – 2014]

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

Select the correct answer using the codes given below:

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

Answer: (c)

Q. Consider the following: [UPSC (Pre) Exam – 2014]

1. Bats
2. Bears
3. Rodents
The phenomenon of hibernation can be observed in which of the above kinds of animals?

(a) 1 and 2 only

(b) 2 only

(d) Hibernation cannot be observed in any of the above

Ans: (c)

Q. Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of [UPSC (Pre) Exam – 2014]

(a) Algae and bacteria

(b) Algae and fungi

(d) Fungi and mosses

Ans: (b)

Q. Which of the following leaf modifications occur(s) in desert areas to inhibit water loss? [UPSC (Pre) – 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

(d) 1, 2 and 3

Ans: (d)

Q. 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? [UPSC (Pre) – 2013]

(a) Ecotone

(b) Ecological niche

(d) Home range

Ans: (b)

Q. In the grasslands, trees do not replace the grasses as a part of an ecological succession because of [UPSC (Pre) – 2013]

(a) Insects and fungi

(b) Limited sunlight and paucity of nutrients

(d) None of the above

Ans: (c)

Q. Which of the following add(s) nitrogen to the soil? [UPSC (Pre) – 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

(d) 1, 2 and 3

Ans: (c)

Q. With reference to the food chains in ecosystems, which of the following kinds of organism is/are known as decomposer organism(s)? [UPSC (Pre) – 2013]

1. Virus
2. Fungi
3. Bacteria
Select the correct answer using the codes given below:

(a) 1 and 3 only

(b) 2 and 3 only

(d) 1, 2 and 3

Ans: (b)

Q. With reference to food chains in ecosystems, consider the following statements: [UPSC (Pre) – 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 populations 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

(d) None of the above

Ans: (a)

Q. Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity? [UPSC (Pre) – 2013]

(a) Oceans, lakes, grasslands, mangroves

(b) Mangroves, oceans, grasslands, lakes

(d) Oceans, mangroves, lakes, grasslands

Ans: (c)

Q. Which of the following can be threat(s) to the biodiversity of a geographical area? [UPSC (Pre) – 2012]

1. Global warming
2. Fragmentation of habitat
3. Invasion of alien species
4. Promotion of vegetarianism
Select the correct answer using the codes given below:

(a) 1, 2 and 3 only

(b) 2 and 3 only

(d) 1, 2, 3 and 4

Ans: (a)

Q. The Millennium Ecosystem Assessment describes the following major categories of ecosystem services – provisioning, supporting regulating, preserving and cultural. Which one of the following is supporting service? [UPSC (Pre) – 2012]

(a) Production of food and water

(b) Control of climate and disease

(d) Maintenance of diversity

Ans: (d)

Q. What would happen if phytoplanktons of an ocean are completely destroyed for some reason? [UPSC (Pre) – 2012]

1. The ocean as a carbon sink would be adversely affected.
2. The food chains in the ocean would be adversely affected.
3. The density of ocean water would drastically decrease.
Select the correct answer using the codes given below:

(a) 1 and 2 only

(b) 2 only

(d) 1, 2 and 3

Ans: (a)

Q. Consider the following: [UPSC (Pre) – 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 the earth?

(a) 1 and 4 only

(b) 2 and 3 only

(d) 1 and 4

Ans: (c)

Q. In the context of ecosystem productivity, marine upwelling zones are important as they increase the marine productivity by bringing the [UPSC (Pre) – 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 only

(b) 2 only

(d) 3 only

Ans: (b)

Q. 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? [UPSC (Pre) – 2010]

(a) Food crop

(b) Rat

(d) Hawk

Ans: (d)

Q. Some species of plants are insectivorous. Why? [UPSC (Pre) – 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.

(d) They have remained in that particular stage of evolution as living fossils, a link between autotrophs and heterotrophs.

Ans: (b)

Q. Epiphytes are plants which depend on other plants for [UPSC (Pre) Exam – 2001]

(a) Food

(b) Mechanical support

(d) Water

Ans: (b)

Q. 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 [UPSC (Pre) – 2000]

(a) Keystone species

(b) Allopatric species

(d) Threatened species

Ans: (a)