Which one of the following is the correct sequence of a food chain?
- (a) Diatoms-Crustaceans-Herrings ✓ UPSC's answer
- (b) Crustaceans-Diatoms-Herrings
- (c) Diatoms-Herrings-Crustaceans
- (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.