Previous year UPSC prelims questions – Ecology basics

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? [UPSC Civil Services Exam – 2022 Prelims]

2. Which of the following are nitrogen-fixing plants?

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

Select the correct answer using the code given below: [UPSC Civil Services Exam – 2022 Prelims]

3. 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 Civil Services Exam – 2021 Prelims]

4. Consider the following kinds of organisms:

1. Copepods
2. Cyanobacteria
3. Diatoms
4. Foraminifera

Which of the above are primary producers in the food chains of oceans? [UPSC Civil Services Exam – 2021 Prelims]

5. Which of the following are detritivores?

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

Select the correct answer using the code given below.

[UPSC Civil Services Exam – 2021 Prelims]

6. What is blue carbon? [UPSC Civil Services Exam – 2021 Prelims]

7. Which of the following have species that can establish a symbiotic relationship with other organisms?

1. 1. Cnidarians
   2. Fungi
   3. Protozoa

Select the correct answer using the code given below. [UPSC Civil Services Exam – 2021 Prelims]

8. The vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions. Which of the following are such conditions?

1. Burrowing animals and termites
2. Fire
3. Grazing herbivores
4. Seasonal rainfall
5. Soil properties

Select the correct answer using the code given below. [UPSC Civil Services Exam – 2021 Prelims]

9. “Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees.” This is the most likely description of [UPSC Civil Services Exam – 2021 Prelims]

10. Which of the following leaf modifications occur (s) in the desert areas to inhibit water loss?

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

Select the correct answer using the code given below:

[UPSC Civil Services Exam – 2018 Prelims]

11. Biological Oxygen Demand (BOD) is a standard criterion for

[UPSC Civil Services Exam – 2017 Prelims]

12. Which one of the following is the best description of the term ‘ecosystem’? [UPSC Civil Services Exam – 2015 Prelims]

13. Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth?

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

Select the correct answer using the code given below. [UPSC Civil Services Exam – 2014 Prelims]

14. Consider the following:

1. Bats
2. Bears
3. Rodents

The phenomenon of hibernation can be observed in which of the above kinds of animals? [UPSC Civil Services Exam – 2014 Prelims]

15. Which one of the following is the correct sequence of a food chain? [UPSC Civil Services Exam – 2014 Prelims]

16. Among the following organisms, which one does not belong to the class of the other three? [UPSC Civil Services Exam – 2014 Prelims]

17. With reference to the food chains in ecosystems, which of the following kinds of organism is/are known as decomposer organism/organisms?

1. Virus
2. Fungi
3. Bacteria

Select the correct answer using the code given below: [UPSC Civil Services Exam – 2013 Prelims]

18. Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity? [UPSC Civil Services Exam – 2013 Prelims]

19. With reference to food chains in ecosystems, consider the following statements:

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? [UPSC Civil Services Exam – 2013 Prelims]

20. 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 Civil Services Exam – 2013 Prelims]

21. Photochemical smog is a resultant of the reaction among [UPSC Civil Services Exam – 2013 Prelims]

22. Acid rain is caused by the pollution of environment by [UPSC Civil Services Exam – 2013 Prelims]

23. In the grasslands, trees do not replace the grasses as a part of an ecological succession because of [UPSC Civil Services Exam – 2013 Prelims]

24. Which of the following adds/add nitrogen to the soil?

1. Excretion of urea by animals
2. Burning of coal by man
3. Death of vegetation

Select the correct answer using the code given below: [UPSC Civil Services Exam – 2013 Prelims]

25. 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 Civil Services Exam – 2012 Prelims]

26. Consider the following kinds of organisms:

1. Bat
2. Bee
3. Bird

Which of the above is/are pollinating agent/agents? [UPSC Civil Services Exam – 2012 Prelims]

27. Which of the following can be threats to the biodiversity of a geographical area?

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: [UPSC Civil Services Exam – 2012 Prelims]

28. Biodiversity forms the basis for human existence in the following ways

1. Soil formation
2. Prevention of soil erosion
3. Recycling of waste
4. Pollination of crops

Select the correct answer on the basis of the codes given below: [UPSC Civil Services Exam – 2011 Prelims]

29. Consider the following:

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? [UPSC Civil Services Exam – 2011 Prelims]

30. If a tropical rainforest is removed, it does not regenerate quickly as compared to a tropical deciduous forest. This is because [UPSC Civil Services Exam – 2011 Prelims]