The citric acid cycle operates only under aerobic conditions because A)oxygen is a reactant in the citric acid cycle. B)oxygen is a product of the citric acid cycle. C) CO2 is a product of the citric acid cycle. D)the NADH and FADH₂ produced by the citric acid cycle can only be reoxidized by the electron transport chain. E)the NAD⁺ and FAD produced by the citric acid cycle can only be reduced by the electron transport chain.

Question

Quizplus · Accepted Answer

The NADH and FADH2 produced by the citric acid cycle can only be reoxidized (or regenerated) by the electron transport chain, which operates only under aerobic conditions because it requires oxygen as the final electron acceptor to generate ATP through oxidative phosphorylation. Without oxygen, the NADH and FADH2 cannot be reoxidized, and the citric acid cycle would come to a halt, leading to a buildup of these molecules and a depletion of the cycle's substrates. Thus, the citric acid cycle is dependent on aerobic respiration and cannot operate under anaerobic conditions. Oxygen is not a reactant or a product of the citric acid cycle. Carbon dioxide is a product of the cycle, but its presence alone does not prevent the cycle from operating in the absence of oxygen. The NAD+ and FAD+ produced by the electron transport chain are not substrates for the citric acid cycle, and their reduction by the electron transport chain does not affect the cycle directly.

The Citric Acid Cycle Operates Only Under Aerobic Conditions Because