Question

Given below are two statements: 
Assertion (A): Hydrolysis of DNA does not form equal numbers of adenine (A) and thymine (T), or guanine (G) and cytosine (C). 
Reason (R): In DNA, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. 
The correct answer is:

• 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 incorrect
• D. A is incorrect but R is correct

Hint:

Key DNA facts: 1. Chargaff's rules: A = T and G = C in any DNA molecule
2. Base pairing: A-T (2 H-bonds), G-C (3 H-bonds)
3. Hydrolysis breaks phosphodiester bonds, not base pairs
4. Equal amounts result from complementary strand pairing

Answer 1

The Correct Option is D

- Evaluation of Assertion (A): DNA hydrolysis produces equal amounts of A and T, and G and C. Thus, A is incorrect.
- Evaluation of Reason (R): The statement about base pairing is accurate. Thus, R is correct.
- Relationship between A and R: R correctly describes base pairing but does not explain A. Thus, the correct choice is (4).

Answer 2

Step 1: Analyze the Assertion (A).
The assertion states that hydrolysis of DNA does not yield equal numbers of adenine (A) and thymine (T), or guanine (G) and cytosine (C).
This is incorrect because Chargaff's rules state that in DNA, the amount of adenine equals thymine, and the amount of guanine equals cytosine.

Step 2: Analyze the Reason (R).
The reason states that adenine forms hydrogen bonds with thymine, and cytosine forms hydrogen bonds with guanine.
This is correct and explains the base pairing rules in DNA structure.

Step 3: Conclusion.
Therefore, Assertion (A) is incorrect, but Reason (R) is correct.