During respiration, pyruvic acid is

Options

A. broken to form a 2-carbon compound and `CO_2`
B. produced in Krebs' cycle
C. formed only if fat is used
D. produced only in aerobic condition

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Respiration**: Respiration is a biological process where organic substances, primarily glucose, are broken down to release energy. This process results in the production of carbon dioxide (CO2) and water (H2O).

2. **Role of Glucose**: In the context of respiration, glucose, which is a 6-carbon compound, undergoes a series of biochemical reactions to be broken down.

3. **Glycolysis Process**: The first step in the breakdown of glucose is glycolysis. During glycolysis, one molecule of glucose is converted into two molecules of pyruvic acid, which is a 3-carbon compound.

4. **Conversion of Pyruvic Acid**: After glycolysis, the pyruvic acid can be further processed. It is converted into acetyl coenzyme A (acetyl CoA), which is a 2-carbon compound. This conversion involves the release of one molecule of carbon dioxide (CO2) through a process called decarboxylation.

5. **Evaluating the Options**:
- **Option 1**: "Broken to form 2 carbon compound and CO2" - This is correct because pyruvic acid (3 carbons) is converted into acetyl CoA (2 carbons) with the release of CO2.
- **Option 2**: "Produced in Krebs cycle" - This is incorrect because pyruvic acid is not produced in the Krebs cycle; it is produced during glycolysis.
- **Option 3**: "Formed only if fat is used" - This is incorrect as pyruvic acid is formed from glucose, not just from fat.
- **Option 4**: "Produced only in aerobic condition" - This is also incorrect because pyruvic acid can be produced in both aerobic and anaerobic conditions.

6. **Conclusion**: Based on the analysis, the correct answer is **Option 1**: "Broken to form 2 carbon compound and CO2".

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