Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): When using intercalating dye, all the molecules must be able to clearly separate in terms of size.
Reason (R): Using intercalating dye permits analysis of DNA fragments in single colour only.
In the light of the above statements, choose the most appropriate answer from the options given below:

• 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:

DNA gels: Separation by size is essential; intercalating dyes show all bands in one color.

Answer 1

The Correct Option is B

Concept: DNA analysis often involves electrophoresis and visualization using intercalating dyes such as ethidium bromide. These dyes bind to DNA and allow visualization under UV light.

Step 1: Understanding Assertion (A).
For proper visualization and analysis, DNA fragments must be clearly separated based on size during electrophoresis. Overlapping fragments make interpretation difficult.
Thus, Assertion (A) is correct.

Step 2: Understanding Reason (R).
Intercalating dyes bind uniformly to DNA and typically produce a single color fluorescence, meaning all DNA fragments appear in the same color.
Thus, Reason (R) is correct.

Step 3: Evaluating relationship.
Although both statements are true, the reason does not explain why size-based separation is necessary. Separation is required for analysis, not because of single-color limitation.

Step 4: Final evaluation.
Thus, both (A) and (R) are correct, but (R) is not the correct explanation of (A). Final Conclusion:
Hence, the correct answer is option (2).