AIIMS2019Chemistry-Molecular Basis of Inheritance

AIIMS 2019 Chemistry DNA Structure MCQ Question

Type: MCQ-conceptual-Medium-Class 12

Assertion : Complementary base pairing occurs in DNA. Reason : This is because adenine is combined with cytosine with a double bond and guanine is combined with thymin with a triple bond.

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Correct Answer

Option D

Detailed Explanation

The statement about complementary base pairing in DNA is fundamentally correct; guanine (G) indeed hydrogen bonds to cytosine (C) and adenine (A) binds to thymine (T) through specific hydrogen bonds (A-T with 2 H-bonds and G-C with 3 H-bonds). However, since the options provided include "N/A" and do not directly address the truth of the statement, option D is the most appropriate choice as it indicates that the question may not fit the standard true/false format. Options A and B are incorrect because they imply a definitive true or false answer, while the statement itself is accurate but not directly addressed by the options.

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