UPSC CSE Prelims
Question 6
Consider the following kinds of organisms:
- Copepods
- Cyanobacteria
- Diatoms
- Foraminifera
Which of the above are primary producers in the food chains of oceans?
View correct answer and explanation
Correct answer: B
Correct Option: B (2 and 3)
Explanation: Marine cyanobacteria and diatoms photosynthesise and form the base of oceanic food webs; copepods and foraminifera are generally consumers.
Statement / Pair / Item-wise Analysis:
1. Incorrect / does not qualify - Copepods are mostly zooplankton that graze on other plankton.
2. Correct / qualifies - Cyanobacteria fix carbon by photosynthesis in the sunlit sea.
3. Correct / qualifies - Diatoms are photosynthetic phytoplankton.
4. Incorrect / does not qualify - Foraminifera are typically heterotrophic protists, not primary producers.
Option-wise Analysis:
A. Incorrect-includes item 1, which is not valid (Copepods are mostly zooplankton that graze on other plankton); omits valid item 3 (Diatoms are photosynthetic phytoplankton).
B. Correct-selects exactly the supported statements/items: 2, 3.
C. Incorrect-includes item 4, which is not valid (Foraminifera are typically heterotrophic protists, not primary producers); omits valid item 2 (Cyanobacteria fix carbon by photosynthesis in the sunlit sea).
D. Incorrect-includes item 1, which is not valid (Copepods are mostly zooplankton that graze on other plankton); includes item 4, which is not valid (Foraminifera are typically heterotrophic protists, not primary producers); omits valid item 2 (Cyanobacteria fix carbon by photosynthesis in the sunlit sea); omits valid item 3 (Diatoms are photosynthetic phytoplankton).