Question

Given below are two statements:
Statement I - Reactions involved in Krebs cycle are anabolic and catabolic.
Statement II - During oxidation of acetyl Co-A, stepwise oxidation of acetyl part of acetyl Co-A occurs.
In light of above statements, choose the most appropriate answer from the option given below.

• A. Both statement I and statement II are correct.
• B. Both statement I and statement II are incorrect.
• C. Statement I is correct and statement II is incorrect.
• D. Statement I is incorrect and statement II is correct.

Hint:

Keyword: Krebs cycle = Amphibolic (Anabolic + Catabolic)

Answer 1

The Correct Option is A

Concept: Krebs cycle (Citric Acid Cycle or TCA cycle) is a central metabolic pathway that plays both catabolic and anabolic roles.
• Catabolic role: Breakdown of acetyl Co-A to release energy (ATP, NADH, FADH$_2$).
• Anabolic role: Provides intermediates for biosynthesis (amino acids, nucleotides, etc.).

Step 1: Analyze Statement I.
Krebs cycle is amphibolic (both anabolic and catabolic). Hence, Statement I is correct.

Step 2: Analyze Statement II.
Acetyl Co-A enters the cycle and its acetyl group (2C) undergoes stepwise oxidation:
• Carbon atoms are released as CO$_2$
• Energy is captured as NADH and FADH$_2$ Hence, Statement II is correct.

Step 3: Conclusion.
Both statements are correct. Final Answer: Option (A)