Which of the following enzymes acts in acidic medium ?

Options

A. Trypsin
B. Pepsin
C. Saliva
D. Amylase.

Answer

To determine which enzyme acts in an acidic medium, we can follow these steps:

### Step 1: Identify the enzymes listed in the options.
The options provided are:
1. Trypsin
2. Pepsin
3. Saliva
4. Amylase

### Step 2: Understand the environment where each enzyme functions.
- **Trypsin**: This enzyme is produced in the pancreas and functions in the small intestine, where the pH is alkaline (basic).
- **Pepsin**: This enzyme is produced in the stomach and is active in an acidic environment (pH around 1.5 to 3.5).
- **Saliva**: This is not an enzyme but a fluid that contains enzymes like amylase, which works in a neutral to slightly alkaline environment.
- **Amylase**: This enzyme, found in saliva and the pancreas, also functions best in a neutral to slightly alkaline environment.

### Step 3: Analyze which enzyme is activated in an acidic medium.
From the analysis:
- **Pepsin** is the only enzyme that is specifically activated and functions in an acidic medium. It is formed from its inactive precursor, pepsinogen, in the presence of hydrochloric acid (HCl) secreted by parietal cells in the stomach.

### Step 4: Conclude the answer.
Thus, the enzyme that acts in an acidic medium is **Pepsin**.

### Final Answer:
**Pepsin** is the enzyme that acts in an acidic medium.

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