Question: 108: Given below are two statements: one is labelled as
Assertion (A) and the other is labelled as Reason (R).
Assertion (A) :
Polymerase chain reaction is used in DNA amplification.
Reason (R) :
The ampicillin resistant gene is used as a selectable marker to check transformation
In the light of the above statements, choose the correct answer from the options given below :
(1) (A) is correct but (R) is not correct
(2) (A) is not correct but (R) is correct
(3) Both (A) and (R) are correct and (R) is the correct explanation of (A)
(4) Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Answer: Option (4)
Explanation:
Polymerase chain reaction (PCR) is a molecular biology technique used to amplify a specific segment of DNA in vitro.
Using repeated cycles of denaturation, annealing, and extension,
PCR can produce millions of copies of a target DNA sequence starting from a very small amount of DNA.
Therefore, Assertion (A) is correct because PCR is directly used for DNA amplification.
The ampicillin resistant gene is commonly used as a selectable marker in cloning vectors.
It helps in identifying and selecting bacterial cells that have successfully taken up
recombinant DNA during the process of genetic transformation.
Thus, Reason (R) is also correct, but it describes a concept related to genetic engineering and
selection of transformants, not DNA amplification by PCR.
Since Reason (R) does not explain Assertion (A),
the correct answer is Option (4).