Question

Assertion (A): Molecular evidence suggests the sister group of sponges is Mesomycetozoa, not choanoflagellates. Reason (R): Sponge collar cells resemble choanoflagellates, suggesting a common ancestor.

• 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:

Sponges have “Collar cells” (Choanocytes). Choanoflagellates have “Collars.” They are the closest relatives!

Answer 1

The Correct Option is D

Step 1: Concept
Sponges (Porifera) are the most basal animals.

Step 2: Meaning
A “sister group” is the closest relative on the tree of life.

Step 3: Analysis
Assertion (A) is incorrect: current molecular evidence strongly supports choanoflagellates as the sister group to all animals. Reason (R) correctly describes the physical evidence for this relationship based on the resemblance of choanoflagellates to sponge choanocytes.

Step 4: Conclusion
The statement about Mesomycetozoa is false, but the physical evidence in (R) is correct.

Final Answer: (D)