Prelims 2021

Q. Consider the following kinds of organisms:
Which of the above are primary producers in the food chains of oceans?

a) 1 and 2
b) 2 and 3
c) 3 and 4
d) 1 and 4
Correct Answer: b) 2 and 3

Question from UPSC Prelims 2021 GS Paper

Explanation : 

Ocean Food Chains: Primary Producers

Primary producers are organisms that can produce their own food using light, water, carbon dioxide, or other chemicals. In the context of ocean food chains, primary producers typically refer to organisms that perform photosynthesis, converting sunlight into chemical energy, which then serves as the base for the ocean’s food web.

Examining Oceanic Organisms:-
Let’s examine the organisms listed:

1. Copepods

Copepods are small crustaceans found in the sea and nearly every freshwater habitat. They are not primary producers; instead, they are consumers that eat primary producers (like phytoplankton) or other small organisms.

2. Cyanobacteria

Cyanobacteria, also known as blue-green algae, are photosynthetic bacteria. They are indeed primary producers because they can produce their own food by photosynthesis, using sunlight to convert carbon dioxide and water into organic compounds.

3. Diatoms

Diatoms are a major group of algae and are among the most common types of phytoplankton. They are also primary producers, as they can perform photosynthesis and produce energy that supports other organisms in the ocean food web.

4. Foraminifera

Foraminifera are a large group of amoeboid protists with reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net. They are not primary producers; they typically feed on diatoms, algae, bacteria, and other small particles in the water.

Given this information, the correct answer is “2 and 3” because both cyanobacteria and diatoms are primary producers in the food chains of oceans. They are capable of photosynthesis and form the base of the marine food web, providing energy and organic material for a wide variety of marine consumers.

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