Assertion : Restriction exonucleases function as molecular scissors.
Reason : These enzymes cleave DNA at or in close proximity to specific recognition sequences.
If both assertion and reason are true and reason is correct explanation of assertion
If both assertion and reason are true both reason is not the correct explanation of assertion.
If assertion is true but reason is false
If assertion is false and reason is true.
The assertion that restriction exonucleases function as molecular scissors is false. Restriction exonucleases are not involved in the process of DNA cleavage. They are enzymes responsible for degrading DNA from the ends by sequentially removing nucleotides.
On the other hand, the reason provided, stating that these enzymes cleave DNA at or in close proximity to specific recognition sequences, is true. This characteristic applies to restriction endonucleases, not restriction exonucleases.
Therefore, the assertion is false, and the reason is true. Option 4 is the correct answer.