Which of the following is an amphoteric molecule in man?

Options

A. Carbonic anhydrase
B. Haemocyanin
C. Haemoglobin
D. Albumin

Answer

To determine which of the following is an amphoteric molecule in humans, we need to understand the definition of an amphoteric molecule. An amphoteric molecule is one that can react with both acids and bases.

### Step-by-Step Solution:

1. **Understand the Definition of Amphoteric Molecules**:
- Amphoteric molecules can act as either acids or bases depending on the environment. This means they can donate protons (H⁺) in the presence of a base and accept protons in the presence of an acid.

2. **Analyze the Given Options**:
- The options provided are:
- Carbonic anhydrase
- Hemocyanin
- Hemoglobin
- Albumin

3. **Evaluate Each Option**:
- **Carbonic Anhydrase**: This is an enzyme that catalyzes the conversion of carbon dioxide and water to carbonic acid. It does not exhibit amphoteric properties.
- **Hemocyanin**: This is a copper-containing protein used for oxygen transport in some invertebrates. It does not behave as an amphoteric molecule.
- **Hemoglobin**: This is a protein in red blood cells responsible for transporting oxygen. Hemoglobin can react with both acids and bases, making it amphoteric.
- **Albumin**: This is a protein that helps maintain osmotic pressure and transport substances in the blood. While it has some buffering capacity, it is not typically classified as amphoteric.

4. **Identify the Correct Answer**:
- Based on the evaluations, hemoglobin is the only molecule among the options that can react with both acids and bases. Therefore, it is the amphoteric molecule in humans.

### Final Answer:
**Hemoglobin** is the amphoteric molecule in humans.

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