Choose the correct enzyme-substrate pair

Options

A. Lipase (carbohydrate)
B. Maltase (lactose)
C. Rennin (casein)
D. Amylase (protein)

Answer

### Step-by-Step Solution

1. **Understanding Enzymes and Substrates**: Enzymes are biological catalysts that speed up chemical reactions in the body. Each enzyme is specific to a particular substrate (the substance on which the enzyme acts).

2. **Evaluating the Options**:
- **Option 1**: Lipase works on carbohydrates.
- **Analysis**: This is incorrect. Lipase is an enzyme that specifically acts on lipids (fats), breaking them down into fatty acids and glycerol.

- **Option 2**: Maltase acts on lactose.
- **Analysis**: This is also incorrect. Maltase is an enzyme that acts on maltose, a disaccharide, converting it into two glucose molecules. It does not act on lactose.

- **Option 3**: Ranine acts on casein.
- **Analysis**: This is correct. Ranine is an enzyme found in the gastric juice of infants and it acts on casein (the main protein in milk), converting it into paracaseinase for digestion.

- **Option 4**: Amylase acts on protein.
- **Analysis**: This is incorrect. Amylase is an enzyme that acts on starch, breaking it down into simpler sugars, not proteins.

3. **Conclusion**: Based on the evaluations, the correct enzyme-substrate pair is the third option: Ranine acts on casein.

### Final Answer
The correct enzyme-substrate pair is: **Ranine acts on casein.**

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