Choose the set of correct statements for hydrogen bonding between complimentary bases of double helix structure of DNA.
a. Responsible for parallel nature of the two DNA strands.
Maintains stability of double helix.
Generates approximately uniform distance between the two strands.

Answer

To solve the question regarding the hydrogen bonding between complementary bases of the double helix structure of DNA, we will evaluate each statement provided and determine their correctness.

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA is a double helical structure composed of two strands that run in opposite directions (anti-parallel). Each strand consists of a sugar-phosphate backbone and nitrogenous bases attached to it.

2. **Evaluating Statement A**:
- **Statement A**: "Responsible for parallel nature of the two DNA strands."
- **Analysis**: This statement is incorrect. The two strands of DNA are anti-parallel, meaning they run in opposite directions (5' to 3' and 3' to 5'). Therefore, hydrogen bonding does not contribute to a parallel nature.
- **Conclusion**: Statement A is **false**.

3. **Evaluating Statement B**:
- **Statement B**: "Maintains stability of double helix."
- **Analysis**: This statement is correct. Hydrogen bonds between complementary bases (adenine-thymine and guanine-cytosine) help stabilize the double helix structure of DNA. The presence of these bonds is crucial for the integrity of the DNA molecule.
- **Conclusion**: Statement B is **true**.

4. **Evaluating Statement C**:
- **Statement C**: "Generates approximately uniform distance between the two strands."
- **Analysis**: This statement is also correct. Hydrogen bonds contribute to maintaining a consistent distance between the two DNA strands, which is approximately 20 Å (Angstroms). This uniform distance is essential for the proper functioning of the DNA structure.
- **Conclusion**: Statement C is **true**.

5. **Final Evaluation**:
- Based on the analysis:
- Statement A is false.
- Statement B is true.
- Statement C is true.
- Therefore, the correct set of statements regarding hydrogen bonding in DNA is that it maintains the stability of the double helix and generates a uniform distance between the two strands.

### Final Answer:
- The correct statements are:
- B. Maintains stability of double helix.
- C. Generates approximately uniform distance between the two strands.

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