2021 GS Paper I, all questions

UPSC Prelims 2021 · GS Paper I

Question 28: Environment and Ecology

Which of the following are detritivores?

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

Select the correct answer using the code given below.

a1, 2 and 4 only
b2, 3, 4 and 5 only
c1, 3 and 5 only
d1, 2, 3, 4 and 5

AnswerUPSC’s answer is (c).

Detritivores feed on dead organic matter, such as fallen leaves and decaying plant and animal remains, and break it into smaller pieces. Earthworms, millipedes and woodlice are classic detritivores of the soil and leaf litter. Jellyfish and seahorses are carnivores that feed on live prey. Remember: detritivores eat detritus; decomposers like fungi and bacteria digest it chemically.

  • 1. Earthworms feed on decaying organic matter in soil.
  • 2. Jellyfish are carnivores that catch live prey.
  • 3. Millipedes feed on decaying plant matter.
  • 4. Seahorses feed on live tiny crustaceans.
  • 5. Woodlice eat decaying plant matter.

How you could have got this

  1. If you were sure statement 2 is not correct, (a), (b) and (d) go: each of them includes 2.

    What you needed to know: Jellyfish are carnivores that catch live prey.

Only (c) is left. You didn’t need statements 1, 3, 4 or 5.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong
  • (a) Wrong: jellyfish and seahorses are carnivores.
  • (b) Wrong: jellyfish and seahorses are carnivores, and it omits earthworms.
  • (c) Right: earthworms, millipedes and woodlice eat dead organic matter.
  • (d) Wrong: it wrongly includes jellyfish and seahorses.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2021, General Studies Paper I, Series A. The paper on upsc.gov.in.