A stronger hydrogen bonding is present in

Options

A. Pleated sheet
B. `alpha` - helix
C. Polymer
D. Hydrogen bond

Answer

To determine where stronger hydrogen bonding is present, we can analyze the context of hydrogen bonding in biological molecules, particularly focusing on DNA and protein structures.

### Step-by-Step Solution:

1. **Understanding Hydrogen Bonds**:
- Hydrogen bonds are weak attractions that occur between a hydrogen atom covalently bonded to an electronegative atom (like oxygen or nitrogen) and another electronegative atom.
- They play a crucial role in stabilizing the structures of biomolecules.

2. **Identifying Locations of Hydrogen Bonds**:
- In DNA, hydrogen bonds form between nitrogenous bases. For example, adenine (A) pairs with thymine (T) through two hydrogen bonds, and cytosine (C) pairs with guanine (G) through three hydrogen bonds.
- In proteins, hydrogen bonds can form between the backbone and side chains, contributing to secondary structures like alpha helices and beta sheets.

3. **Comparing Strengths of Hydrogen Bonds**:
- The strength of hydrogen bonds can vary based on the environment and the specific atoms involved.
- In the context of DNA, the hydrogen bonds between base pairs are crucial for the stability of the double helix structure.
- In proteins, the hydrogen bonds in alpha helices are also significant, but they are generally not as strong as the hydrogen bonds formed between complementary base pairs in DNA.

4. **Conclusion**:
- Based on the analysis, the strongest hydrogen bonding is found in the DNA structure, particularly in the hydrogen bonds between the nitrogenous bases.
- Therefore, the answer is that stronger hydrogen bonding is present in the alpha helix of DNA.

### Final Answer:
The stronger hydrogen bonding is present in the alpha helix of DNA.

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