During respiration……………………..

Options

A. 2 PGAL during glycolysis and none in Krebs cycle
B. 2 PGAL during glycolysis and two pyruvic acid in Krebs cycle
C. 2 PGAL during glycolysis and 4 pyruvic acid in Krebs cycle
D. PGAL is not produced during respiratory events.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question refers to the involvement of two specific molecules, 2-phosphoglyceraldehyde (2-PGAL) and pyruvic acid, in the processes of glycolysis and the Krebs cycle during respiration.

2. **Identifying the Pathways:**
- **Glycolysis:** This is the first step in cellular respiration where glucose is broken down to produce energy. It occurs in the cytoplasm and results in the production of pyruvic acid.
- **Krebs Cycle (Citric Acid Cycle):** This occurs in the mitochondria after glycolysis and involves further breakdown of products from glycolysis to produce energy carriers.

3. **Role of 2-Phosphoglyceraldehyde (2-PGAL):**
- 2-PGAL is an intermediate formed during glycolysis. Specifically, it is produced from 3-phosphoglycerate through a reaction catalyzed by the enzyme phosphofructokinase.
- It is important to note that 2-PGAL is not produced in the Krebs cycle; it is solely a product of glycolysis.

4. **Role of Pyruvic Acid:**
- Pyruvic acid is the end product of glycolysis. It is formed from phosphoenolpyruvate during the glycolytic pathway.
- Similar to 2-PGAL, pyruvic acid is not produced in the Krebs cycle; it is a product of glycolysis and is then converted into acetyl-CoA to enter the Krebs cycle.

5. **Conclusion:**
- Both 2-PGAL and pyruvic acid are products of glycolysis and are not involved in the Krebs cycle. Therefore, the statement that "2-phosphoglyceraldehyde during glycolysis and none in Krebs cycle" is correct.

**Final Answer:**
- 2-phosphoglyceraldehyde is produced during glycolysis and is not produced in the Krebs cycle. Pyruvic acid is also produced during glycolysis and is not produced in the Krebs cycle.

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