NEET Biology: Biology - Molecular Biology questions with solutions

Q1. Assertion A change in nitrogen base at the third position of a codon causes change in the expression of the codon. Reason A codon is mostly read by all the three nitrogen bases.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Answer: Assertion is correct but Reason is incorrect

The assertion is correct because a change at the third codon position can alter codon meaning in some cases, though often it does not due to degeneracy. The reason is incorrect because the third base is not usually read with the same strictness as the first two; wobble pairing makes it less decisive.