Select the correct option regarding restriction endonuclease
P. 900 restriction enzyme have been isolated from over 200 strains.
Q. The first restriction exonuclease was Hind II.
R. Each restriction endonuclease recognises same palindromic sequence .

Options

A. All are incorrect
B. P and Q are correct
C. Q and R are incorrect
D. All are correct

Answer

To solve the question regarding restriction endonucleases, we will evaluate each statement (P, Q, and R) provided in the question.

### Step-by-Step Solution:

1. **Evaluate Statement P:**
- Statement P claims that "900 restriction enzymes have been isolated from over 200 strains."
- This statement is partially correct. While it is true that around 900 restriction enzymes have been isolated, they have been isolated from approximately 230 strains of bacteria, not just over 200. Therefore, this statement is **incorrect**.

2. **Evaluate Statement Q:**
- Statement Q states that "The first restriction exonuclease was Hind II."
- This statement is also incorrect. Hind II is actually the first restriction **endonuclease** that was discovered, not an exonuclease. Exonucleases cut DNA at the ends, while endonucleases cut within the DNA strand. Therefore, this statement is **incorrect**.

3. **Evaluate Statement R:**
- Statement R claims that "Each restriction endonuclease recognizes the same palindromic sequence."
- This statement is incorrect as well. Each restriction endonuclease has its own specific recognition site, which is a palindromic sequence, but these sequences vary between different endonucleases. Therefore, this statement is **incorrect**.

### Conclusion:
All three statements (P, Q, and R) are incorrect. Thus, the correct answer is that all statements are incorrect.