Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The molecular evidences suggest that the sister group of sponges is not choanoflagellates, but mesomycetozoa, a group of parasitic protists. So, can this hypothesis be correct given that these parasites lack collar cells?
Reason (R): The collar cells of sponges bear a significant resemblance to a choanoflagellate cell suggesting that the last common ancestor of animals and their protist sister group might have resembled a choanoflagellate. In this regard, mesomycetozoans could still be sister group of animals. The lack of collar cells in mesomycetozoans would indicate that over the time, their structure evolved in a way that it no longer resembled a choanoflagellate cell pointing out to convergent evolution.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A).
• C. (A) is correct but (R) is not correct.
• D. (A) is not correct but (R) is correct.

Hint:

A sister group may lose a trait (collar cells) over time, so lack of collar cells does not rule out mesomycetozoans as the sister group of animals.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:

• The Assertion asks whether the molecular evidence placing mesomycetozoans as the sister group of animals can be correct despite their lack of collar cells.

Step 2: Detailed Explanation:

• Sponge collar cells resemble choanoflagellate cells, so the last common ancestor of animals and their protist sister group may have resembled a choanoflagellate.

• Mesomycetozoans can still be the sister group of animals if they secondarily lost the collar-cell structure over time, which is the explanation given in the Reason.

• Thus both statements hold and R explains why A can be correct.

Step 3: Final Answer:
The correct option is (A) Both (A) and (R) are correct and (R) is the correct explanation of (A).