Correct statement about restriction endonuclease.
(I) It is the enzyme which cuts DNA at a particular point.
(II) The first restriction endonuclease was Hindll.
(III) Overall,900 restriction enzymes have been isolated from about 200 strains.
(IV) Each restriction endonuclease recognizes a specific palindromic sequence.

Options

A. I and IV are correct
B. I and II are incorrect
C. I and III are incorrect
D. I,II and IV are correct

Answer

To determine the correct statements about restriction endonucleases, let's analyze each statement one by one:

1. **Statement I**: "It is the enzyme which cuts DNA at a particular point."
- **Analysis**: This statement is true. Restriction endonucleases are enzymes that recognize specific sequences in DNA and cut the DNA at those sites.

2. **Statement II**: "The first restriction endonuclease was HindII."
- **Analysis**: This statement is incorrect. The first restriction endonuclease to be discovered was actually HindII, not Hindll. The correct name is HindII.

3. **Statement III**: "Overall, 900 restriction enzymes have been isolated from about 200 strains."
- **Analysis**: This statement is incorrect. While many restriction enzymes have been isolated, the number of strains is actually around 230, not 200. Therefore, this statement does not hold true.

4. **Statement IV**: "Each restriction endonuclease recognizes a specific palindromic sequence."
- **Analysis**: This statement is true. Each restriction enzyme recognizes a specific palindromic sequence in the DNA, which is crucial for their function in cutting DNA.

**Conclusion**: The correct statements are I, IV, and the corrected version of II (HindII). Therefore, the correct answer includes statements I, IV, and the corrected version of II.

### Final Answer:
The correct statements about restriction endonucleases are:
- Statement I: True
- Statement II: False (correct name is HindII)
- Statement III: False
- Statement IV: True

Thus, the correct statements are I and IV.