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 need to 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 incorrect. In reality, over 900 restriction enzymes have been isolated from more than 230 strains of bacteria. Therefore, this statement is false.

2. **Evaluate Statement Q:**
- Statement Q states that "The first restriction exonuclease was Hind II."
- This statement is also incorrect. The first restriction endonuclease discovered was actually Hind II, but it is important to clarify that Hind II is an endonuclease, not an exonuclease. Thus, this statement is false.

3. **Evaluate Statement R:**
- Statement R asserts that "Each restriction endonuclease recognizes the same palindromic sequence."
- This statement is incorrect. Different restriction endonucleases recognize different specific palindromic sequences. Therefore, this statement is false.

4. **Conclusion:**
- Since all three statements (P, Q, and R) are incorrect, the correct option regarding the restriction endonuclease is that "all are incorrect."

Thus, the correct answer is **Option 1: All are incorrect.**