Which of the following is not an intermediate in Krebs cycle ?

Options

A. Acetic acid
B. Succinyl coenzyme-A
C. Malic acid
D. Citric acid

Answer

**Step-by-Step Solution:**

1. **Understanding the Krebs Cycle**: The Krebs cycle, also known as the tricarboxylic acid (TCA) cycle or citric acid cycle, is a series of chemical reactions used by all aerobic organisms to generate energy. It takes place in the mitochondria and is a crucial part of cellular respiration.

2. **Identifying Intermediates**: The Krebs cycle involves several key intermediates. The main intermediates include:
- Acetyl CoA
- Citrate (citric acid)
- Isocitrate
- Alpha-ketoglutarate
- Succinyl CoA
- Succinate
- Fumarate
- Malate
- Oxaloacetate

3. **Analyzing the Options**: The question provides four options:
- Acetic acid
- Succinyl coenzyme A
- Amylic acid
- Citric acid

4. **Evaluating Each Option**:
- **Acetic acid**: This is not an intermediate in the Krebs cycle. It is a simple carboxylic acid but does not appear in the cycle.
- **Succinyl coenzyme A**: This is indeed an intermediate in the Krebs cycle.
- **Amylic acid**: This is not a recognized intermediate in the Krebs cycle.
- **Citric acid**: This is the same as citrate, which is an intermediate in the Krebs cycle.

5. **Conclusion**: Among the options, acetic acid is not an intermediate in the Krebs cycle. Therefore, the correct answer is **acetic acid**.

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