Respiratory intermediate which undergoes fermentation is generally

Options

A. Glyceraldehyde 3-phosphate
B. 2-phosphoglyceric acid
C. PEP
D. Pyruvic acid

Answer

To solve the question regarding the respiratory intermediate that undergoes fermentation, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context of the Question**: The question asks about a respiratory intermediate that can undergo fermentation. Fermentation is an anaerobic process that occurs when oxygen is not available.

2. **Identify the Options**: The options provided are:
- Glyceraldehyde 3-phosphate
- 2-phosphoglyceric acid
- PEP (Phosphoenolpyruvate)
- Pyruvic acid

3. **Recall the Glycolysis Pathway**: Glycolysis is the metabolic pathway that converts glucose into pyruvic acid. This pathway is common to both aerobic and anaerobic respiration.

4. **Determine the End Product of Glycolysis**: The end product of glycolysis is pyruvic acid, which is a three-carbon compound.

5. **Understand Fermentation**: Pyruvic acid can undergo fermentation when oxygen is not present. There are two main types of fermentation:
- **Alcoholic Fermentation**: Pyruvic acid is converted into ethanol and carbon dioxide.
- **Lactic Acid Fermentation**: Pyruvic acid is converted into lactate (lactic acid).

6. **Conclusion**: Since pyruvic acid is the direct product of glycolysis and is known to undergo fermentation, the correct answer to the question is **pyruvic acid**.

### Final Answer:
The respiratory intermediate which undergoes fermentation is generally **pyruvic acid**.

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