Krebs' cycle is also called metabolic sink as it is a common pathway for

Options

A. carbohydrates, fats and proteins (amino acids)
B. carbohydrates and fats only
C. carbohydrates and organic acids only
D. proteins and fats only

Explanation

**Step-by-Step Solution:**

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

2. **Definition of Metabolic Sink**: The term "metabolic sink" refers to a common pathway where various metabolic byproducts converge. In the context of the Krebs cycle, it means that different nutrients (carbohydrates, fats, and proteins) are broken down into simpler molecules that enter the cycle.

3. **Nutrient Breakdown**:
- **Carbohydrates**: They are broken down into glucose, which is then converted into pyruvate through glycolysis. Pyruvate is further converted into acetyl-CoA, which enters the Krebs cycle.
- **Proteins**: Proteins are broken down into amino acids. Specific amino acids, like glutamate, can be converted into alpha-ketoglutarate, which is an intermediate in the Krebs cycle.
- **Fats**: Fats are broken down into fatty acids and glycerol. Fatty acids undergo beta-oxidation to form acetyl-CoA, which also enters the Krebs cycle.

4. **Common Pathway**: All these byproducts (acetyl-CoA from carbohydrates, alpha-ketoglutarate from proteins, and acetyl-CoA from fats) enter the Krebs cycle, making it a common pathway for the metabolism of carbohydrates, fats, and proteins.

5. **Conclusion**: Therefore, the Krebs cycle is referred to as a metabolic sink because it serves as a common pathway for the breakdown products of carbohydrates, fats, and proteins, allowing them to be utilized for energy production.

**Final Answer**: The Krebs cycle is called a metabolic sink as it is a common pathway for carbohydrates, fats, and proteins.

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