Question

Assertion (A) : Chemically synthesised oligonucleotides are used during annealing in PCR technique.
Reason (R) : The primers bind to the double stranded DNA at their complementary regions.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Primers are synthetic oligonucleotides (true), but they anneal to single stranded DNA, not double stranded DNA (false).

Answer 1

The Correct Option is C

Step 1: Recall the PCR steps:
PCR has three steps: denaturation, annealing and extension. In denaturation, heat separates the double stranded DNA into two single strands.

Step 2: Check the Assertion:
In annealing, two chemically synthesised oligonucleotides, called primers, attach to the template. So (A) is true.

Step 3: Check the Reason:
The primers bind to the single stranded template DNA at their complementary regions, not to double stranded DNA, because the strands have already been separated. So (R) is false.

Step 4: Select the code:
A is true, R is false. So option (C).

Final Answer:
The correct option is (C).