The initial step in the digestion of milk in humans is carried out by?

Options

A. Lipase
B. Trypsin
C. Rennin
D. Pepsin

Answer

To answer the question, "The initial step in the digestion of milk in humans is carried out by?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Milk Composition**:
- Milk contains various components, including proteins, fats, and carbohydrates. The primary protein in milk is casein.

2. **Identifying the Initial Digestion Process**:
- The digestion of milk begins with the breakdown of its proteins, particularly casein.

3. **Role of Enzymes in Digestion**:
- Enzymes are biological catalysts that facilitate the breakdown of complex molecules into simpler ones. In the case of milk, specific enzymes are responsible for the digestion of casein.

4. **Identifying the Key Enzyme**:
- The enzyme responsible for the initial digestion of casein in milk is called renin (also known as rennin). It is secreted in an inactive form known as pro-renin.

5. **Activation of Renin**:
- Pro-renin is activated to renin, which then acts on casein to convert it into para-casein. This conversion is crucial as it marks the beginning of protein digestion in milk.

6. **Conclusion**:
- Therefore, the initial step in the digestion of milk in humans is carried out by the enzyme renin.

### Final Answer:
The initial step in the digestion of milk in humans is carried out by **renin**.

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