Mark the incorrect statement for DNA.

Options

A. The ratios between Adenine and Thymine and Guanine and Cytosine are constant and equal to one in dsDNA.
B. DNA is an acidic substance present in the nucleus was first identified by Friedrich Meischer in 1869.
C. The X - ray diffraction data was used for discovery of the DNA
D. Two strands are anti- parallel to each other.

Answer

To solve the question "Mark the incorrect statement for DNA," we need to analyze each statement provided and determine which one is incorrect.

### Step-by-Step Solution:

1. **Understand the Statements**: We have several statements regarding DNA. Let's break them down one by one.

2. **Statement Analysis**:
- **Statement 1**: "Ratio between adenine and thymine and guanine and cytosine are constant and equal to 1 in double-stranded DNA."
- This statement is incorrect. While adenine pairs with thymine and guanine pairs with cytosine, the ratio of adenine to thymine and guanine to cytosine is not necessarily equal to 1 in all DNA. The correct relationship is that A = T and G = C, but the total amounts can vary.

- **Statement 2**: "DNA is an acidic substance present in the nucleus, first identified by Friedrich Miescher in 1869."
- This statement is correct. DNA is indeed an acidic substance and was first identified by Friedrich Miescher.

- **Statement 3**: "X-ray diffraction data was used for the discovery of DNA."
- This statement is also correct. X-ray diffraction was crucial in determining the structure of DNA.

- **Statement 4**: "Strands of DNA are antiparallel to each other."
- This statement is correct. The two strands of DNA run in opposite directions, which is referred to as being antiparallel.

3. **Conclusion**: After analyzing all the statements, we find that the first statement is incorrect. Therefore, the answer to the question is that the incorrect statement is the first one.

### Final Answer:
The incorrect statement for DNA is: "Ratio between adenine and thymine and guanine and cytosine are constant and equal to 1 in double-stranded DNA."

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