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?
- (a) 1 and 2
- (b) 2 and 3 ✓ UPSC's answer
- (c) 3 and 4
- (d) 1 and 4
Why the answer is (b)
• Primary producers make their own food by photosynthesis; in oceans this is phytoplankton.
• Cyanobacteria (e.g. Prochlorococcus, Synechococcus) are photosynthetic bacteria and among the most abundant ocean producers (item 2).
• Diatoms are silica-shelled photosynthetic algae responsible for a large share of marine primary production (item 3).
• Copepods (1) are tiny crustaceans that graze on phytoplankton — primary consumers; foraminifera (4) are shelled protozoa that feed on other organisms — consumers.
• Hence 2 and 3, option (b).
Why the other options are wrong
- (a) 1 and 2
- Copepods are consumers that graze on plankton.
- (c) 3 and 4
- Foraminifera are consumers, not producers.
- (d) 1 and 4
- Both copepods and foraminifera are consumers.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2021, held on 10 October 2021. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.