Question

QUESTION 25 The citric acid cycle cannot function if o2 is not available; why is this OA. O2 is required for the redox reactions of the citric acid cycle. B. All of these answers are correct OC. The electron transport chain will not function without 02, thus the NAD+ and FAD needed for the citric acid cycle will not be regenerated. OD. None of these answers are correct O E 02 is the final electron acceptor of the citric acid cycle, without which oxaloacetate cannot be produced.

Answer 1

Option C will be correct.

For one molecule of acetyl coA entering the citric acid cycle, 3 molecules of NADH and 1 molecule of FADH2 are produced. These two are high energy molecules, that donate their electrons to the electron transport chain. The electrons donated by NADH and FADH2 are passed through various complexes, and is finally transferred to the terminal electron acceptor, oxygen. As NADH and FADH2 donate electrons, NAD+ and FAD are generated, which functions as electron carrier in the citric acid cycle.

Thus, in absence of oxygen, electron transport chain will not function. Electrons will not be removed from NADH and FADH2, and NAD+ and FAD will not be generated. This will lead to accumulation of NADH and FADH2 within the cell. In the absence of NAD+ and FAD, the citric acid cycle will not operate. Thus, absence of oxygen stops the citric acid cycle.