Read the following statements and select the correct ones.
(i) Same kind of sticky ends are produced when a DNA has been cut by different restriction enzymes.
(ii) Exonucleases make cuts at specific positions within the DNA.
(iii) Hind ll was the first restriction endonuclease to be isolated.
(iv) A bacteriophage has the ability to replicate within bacterial cells by integrating its DNA with bacterial DNA.
(v) Presence of more than one recognition sites for a enzyme within the vector facilitates the gene cloning.

Options

A. (i),(iii) and (v)
B. (ii) and (iv)
C. (iii) and (iv)
D. (ii),(iii) and (iv)

Explanation

To solve the question, we will analyze each statement one by one to determine which ones are correct.

### Step-by-Step Solution:

1. **Statement (i)**: "Same kind of sticky ends are produced when a DNA has been cut by different restriction enzymes."
- **Analysis**: This statement is incorrect. Different restriction enzymes cut DNA at different recognition sites, which can result in different types of sticky ends. Only the same restriction enzyme will produce the same sticky ends.
- **Conclusion**: This statement is **incorrect**.

2. **Statement (ii)**: "Exonucleases make cuts at specific positions within the DNA."
- **Analysis**: This statement is also incorrect. Exonucleases remove nucleotides from the ends of DNA molecules and do not make cuts at specific internal positions. Endonucleases are the enzymes that cut DNA at specific sites.
- **Conclusion**: This statement is **incorrect**.

3. **Statement (iii)**: "Hind II was the first restriction endonuclease to be isolated."
- **Analysis**: This statement is correct. Hind II (often referred to as HindII) was indeed one of the first restriction enzymes to be discovered and isolated.
- **Conclusion**: This statement is **correct**.

4. **Statement (iv)**: "A bacteriophage has the ability to replicate within bacterial cells by integrating its DNA with bacterial DNA."
- **Analysis**: This statement is correct. Bacteriophages can integrate their DNA into the bacterial genome, allowing them to replicate within bacterial cells.
- **Conclusion**: This statement is **correct**.

5. **Statement (v)**: "Presence of more than one recognition site for an enzyme within the vector facilitates gene cloning."
- **Analysis**: This statement is incorrect. Having multiple recognition sites can complicate the cloning process as it may lead to the generation of multiple fragments, making it harder to isolate the desired fragment.
- **Conclusion**: This statement is **incorrect**.

### Final Conclusion:
The correct statements are **(iii)** and **(iv)**. Therefore, the answer to the question is that statements 3 and 4 are correct.

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