The only enzyme that catalyses the reduction of substrate in the biochemical reactions of Anaerobic respiration is

Options

A. Pyruvate decarboxylase
B. Glyceraldehyde phosphate dehydrogense
C. Alcohol dehydrogenase
D. Enolase

Answer

**Step-by-Step Solution:**

1. **Understanding Anaerobic Respiration**: Anaerobic respiration occurs in the absence of oxygen and involves the conversion of glucose into energy. In yeast, this process produces ethanol and carbon dioxide.

2. **Identifying the Key Reactions**: The main substrate in anaerobic respiration is pyruvate, which is derived from glycolysis. The conversion of pyruvate is crucial to the process.

3. **Enzymes Involved**: Several enzymes are involved in anaerobic respiration, but we need to focus on the one that catalyzes the reduction of substrate. The options given are:
- Option 1: Pyruvate decarboxylase
- Option 2: Glyceryldehyde phosphate dehydrogenase
- Option 3: Alcohol dehydrogenase
- Option 4: Enolase

4. **Analyzing Each Option**:
- **Pyruvate Decarboxylase**: This enzyme catalyzes the decarboxylation of pyruvate, removing CO2 and converting it into acetaldehyde.
- **Glyceryldehyde Phosphate Dehydrogenase**: This enzyme is involved in glycolysis but does not directly participate in the reduction of substrates in anaerobic respiration.
- **Alcohol Dehydrogenase**: This enzyme catalyzes the reduction of acetaldehyde to ethanol, which is a key step in anaerobic respiration.
- **Enolase**: This enzyme is involved in glycolysis and does not catalyze the reduction of substrates in anaerobic respiration.

5. **Conclusion**: The only enzyme that catalyzes the reduction of substrate in the biochemical reactions of anaerobic respiration is **Alcohol Dehydrogenase**.

**Final Answer**: Alcohol Dehydrogenase (Option 3)

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