UPSC Prelims 2014 GS Paper I · Q80 of 100 Environment & Ecology easy

Which one of the following is the correct sequence of a food chain?

  1. (a) Diatoms-Crustaceans-Herrings ✓ UPSC's answer
  2. (b) Crustaceans-Diatoms-Herrings
  3. (c) Diatoms-Herrings-Crustaceans
  4. (d) Crustaceans-Herrings-Diatoms

Why the answer is (a)

• In a marine food chain energy flows from producers to consumers: diatoms (phytoplankton) photosynthesise, crustaceans such as copepods graze on them, and herrings feed on the crustaceans.

• Diatoms → Crustaceans → Herrings is therefore the correct order — option (a).

• The other options place a consumer before its food source.

• Hence option (a).

Why the other options are wrong

(b) Crustaceans-Diatoms-Herrings
Crustaceans eat diatoms, not the reverse.
(c) Diatoms-Herrings-Crustaceans
Herrings eat crustaceans, not the reverse.
(d) Crustaceans-Herrings-Diatoms
Diatoms are producers and come first.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2014, held on 24 August 2014. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

Reading the answer is not the same as getting it right under a clock. Practise this question with UPSC's negative marking, and anything you miss goes into an error notebook until you get it right twice.

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