Assertion. Krebs cycle is regarded the amphibolic (central) pathway of the cell.
Reason. Catabolic pathways converge on it and anabolic pathways diverge from it.

Options

A. If both A and R are true and R is the correct explanation of A.
B. If both A and R are true but R is not the correct explanation of A.
C. If A is true but R is false.
D. If both A and R are false.

Answer

To solve the question, we need to analyze the assertion and reason provided:

### Step 1: Understand the Assertion
The assertion states that the Krebs cycle is regarded as the amphibolic (central) pathway of the cell.
- The Krebs cycle, also known as the citric acid cycle or TCA cycle, is a crucial metabolic pathway that plays a role in both catabolism (breaking down molecules for energy) and anabolism (building up molecules).

### Step 2: Analyze the Reason
The reason given is that catabolic pathways converge on the Krebs cycle and anabolic pathways diverge from it.
- Catabolic pathways involve the breakdown of complex molecules into simpler ones, which then enter the Krebs cycle as Acetyl-CoA.
- Anabolic pathways involve the synthesis of complex molecules from simpler ones, utilizing intermediates from the Krebs cycle.

### Step 3: Evaluate the Truth of Both Statements
- Both the assertion and reason are true. The Krebs cycle is indeed a central pathway where catabolic processes feed into it, and from it, various anabolic processes can occur.

### Step 4: Determine the Relationship Between Assertion and Reason
- The reason provided correctly explains the assertion. The convergence of catabolic pathways into the Krebs cycle and the divergence of anabolic pathways from it illustrates why the Krebs cycle is considered amphibolic.

### Conclusion
Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Final Answer
Both A and R are true, and R is the correct explanation of A.

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