Citric acid cycle is…….step in carbohydrate metabolism

Options

A. First
B. Second
C. Third
D. Fourth

Answer

### Step-by-Step Solution:

1. **Understanding the Citric Acid Cycle**: The citric acid cycle, also known as the tricarboxylic acid (TCA) cycle or Krebs cycle, is a crucial metabolic pathway that plays a significant role in carbohydrate metabolism.

2. **Role in Aerobic Organisms**: The citric acid cycle occurs in aerobic organisms, which are organisms that require oxygen for respiration. It is involved in the breakdown of carbohydrates to release stored energy.

3. **Carbohydrate Metabolism Overview**: Carbohydrate metabolism consists of several steps. The first step is glycolysis, where glucose (a six-carbon compound) is broken down into two molecules of pyruvate (three-carbon compounds).

4. **Link Reaction**: After glycolysis, the second step is the link reaction, where pyruvate is converted into acetyl coenzyme A (acetyl CoA). This step serves as a bridge between glycolysis and the citric acid cycle.

5. **Citric Acid Cycle as the Third Step**: The citric acid cycle is the third step in carbohydrate metabolism. In this cycle, acetyl CoA enters and undergoes a series of reactions that produce energy carriers such as NADH and FADH2, as well as ATP.

6. **Conclusion**: Therefore, the citric acid cycle is the third step in carbohydrate metabolism.

### Final Answer:
The citric acid cycle is the **third step** in carbohydrate metabolism.

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