Select the wrong statements with respect to DNA .
(i) The backbone of DNA is formed by the sugar-phosphate chain.
(ii) The two strands of the Polynucleotide are anti-parallel.
(iii) The nitrogen bases are parallel to the backbone .
(iv) The backbone contains a hydrogen bond.

Options

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

Answer

To determine the wrong statements regarding DNA, let's analyze each statement one by one:

1. **Statement (i)**: "The backbone of DNA is formed by the sugar-phosphate chain."
- This statement is **correct**. The backbone of DNA consists of alternating sugar (deoxyribose) and phosphate groups, forming a sugar-phosphate chain.

2. **Statement (ii)**: "The two strands of the Polynucleotide are anti-parallel."
- This statement is also **correct**. In DNA, the two strands run in opposite directions, meaning one strand runs from the 5' to 3' direction while the other runs from 3' to 5', which is referred to as being anti-parallel.

3. **Statement (iii)**: "The nitrogen bases are parallel to the backbone."
- This statement is **incorrect**. The nitrogenous bases do not run parallel to the backbone; instead, they protrude from the sugar-phosphate backbone and are oriented towards the interior of the double helix, forming hydrogen bonds with complementary bases from the opposite strand.

4. **Statement (iv)**: "The backbone contains a hydrogen bond."
- This statement is **incorrect**. The hydrogen bonds in DNA are formed between the nitrogenous bases of the two strands, not within the backbone itself. The backbone consists solely of sugar and phosphate groups.

### Conclusion:
The wrong statements are:
- Statement (iii): "The nitrogen bases are parallel to the backbone."
- Statement (iv): "The backbone contains a hydrogen bond."

### Final Answer:
The wrong statements are (iii) and (iv).

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