Pepsin acts in

Options

A. basic medium
B. acidic medium
C. neutral medium
D. all types of medium.

Answer

### Step-by-Step Solution:

1. **Understanding Pepsin**: Pepsin is a proteolytic enzyme, meaning it is involved in the breakdown of proteins into smaller peptides.

2. **Inactive Form**: Pepsin is initially produced in an inactive form known as pepsinogen. This is important because enzymes often need to be activated to perform their function.

3. **Activation of Pepsinogen**: The conversion of pepsinogen into its active form, pepsin, occurs in the presence of hydrochloric acid (HCl), which is secreted in the stomach.

4. **Role of Hydrochloric Acid**: HCl creates an acidic environment in the stomach. The pH of this environment is typically below 7, which is considered acidic.

5. **Function of Pepsin**: Once activated, pepsin acts on proteins, breaking them down into smaller fragments known as proteoses and peptones.

6. **Conclusion**: Since pepsin is activated in the presence of hydrochloric acid and functions optimally in an acidic medium, we conclude that pepsin acts in an acidic medium.

### Final Answer:
Pepsin acts in the acidic medium.

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