Select the incorrect statement with respect to adult human hemoglobin.

Options

A. It is quaternary structure.
B. It contain four non identical polypeptides.
C. It contains two alpha and two bata chains .
D. Both alpha chains are identical .

Answer

To solve the question regarding the incorrect statement about adult human hemoglobin, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Understanding Hemoglobin Structure**:
- Hemoglobin (Hb) is a protein found in red blood cells responsible for transporting oxygen. It consists of four polypeptide chains and four heme groups, which contain iron.

2. **Analyzing Each Statement**:
- **Statement 1**: "It is a quaternary structure."
- **Analysis**: Hemoglobin indeed has a quaternary structure due to the presence of four polypeptide chains that are closely packed.
- **Conclusion**: This statement is **correct**.

- **Statement 2**: "It contains four non-identical polypeptides."
- **Analysis**: Hemoglobin consists of two identical alpha chains (Alpha 1 and Alpha 2) and two identical beta chains (Beta 1 and Beta 2). Therefore, it does not contain four non-identical polypeptides.
- **Conclusion**: This statement is **incorrect**.

- **Statement 3**: "It contains two alpha and two beta chains."
- **Analysis**: This is accurate as hemoglobin is made up of two alpha chains and two beta chains.
- **Conclusion**: This statement is **correct**.

- **Statement 4**: "Both alpha chains are identical."
- **Analysis**: The two alpha chains (Alpha 1 and Alpha 2) are indeed identical in length and structure.
- **Conclusion**: This statement is **correct**.

3. **Identifying the Incorrect Statement**:
- After analyzing all the statements, the incorrect statement is: "It contains four non-identical polypeptides."

### Final Answer:
The incorrect statement with respect to adult human hemoglobin is: **"It contains four non-identical polypeptides."**

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