Question

Assertion (A): In RNA, thymine is replaced by uracil.
Reason (R): Uracil pairs with adenine during base pairing.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Remember: \[ \text{DNA} \rightarrow \text{Contains Thymine} \] \[ \text{RNA} \rightarrow \text{Contains Uracil} \]

Answer 1

The Correct Option is B

Step 1: Check Assertion (A). RNA contains: \[ \text{Adenine, Guanine, Cytosine and Uracil} \] Instead of thymine, RNA contains uracil. Hence Assertion (A) is true.

Step 2: Check Reason (R). Uracil pairs with adenine through hydrogen bonding. Hence Reason (R) is also true.

Step 3: Check explanation relation. The reason states the pairing property of uracil, but it does not explain why thymine is absent in RNA. Thus: \[ \boxed{\text{Both A and R are true but R is not the correct explanation}} \]