Krebs cycle, also known as the TCA cycle, serves dual roles in metabolism. The correct answer to the question “Krebs (TCA) cycle is ________ pathway” is (C) an amphibolic.​

Correct Answer

C) an amphibolic
The Krebs cycle is classified as amphibolic because it functions in both catabolism (breaking down acetyl-CoA to produce energy via NADH, FADH2, and ATP) and anabolism (providing intermediates like α-ketoglutarate and oxaloacetate for biosynthesis of amino acids, nucleotides, and glucose).​

Option Breakdown

Only Anabolic (A)

Anabolic pathways build complex molecules from simpler ones, consuming energy (e.g., gluconeogenesis). Krebs cycle is not solely anabolic, as it primarily generates energy through oxidation.​

Only Catabolic (B)

Catabolic pathways degrade molecules to release energy (e.g., glycolysis). While Krebs cycle oxidizes acetyl-CoA to CO2 and reduces electron carriers, it also supplies precursors for synthesis, ruling out this option.​

An Amphibolic (C)

This term describes pathways serving both catabolic and anabolic roles. Krebs cycle intermediates diverge for anabolic processes like amino acid synthesis while converging catabolic products like pyruvate.​

A Pyogenic (D)

Pyogenic refers to pus-forming infections, unrelated to metabolic pathways. This is a distractor with no biochemical relevance.​