Which statement about the citric acid cycle is false? a) CO2 is released during the cycle. b) It occurs in the mitochondrial matrix. c) It does not operate under anaerobic conditions. d) It requires NAD+ and FAD. e) It releases less energy than glycolysis.

The false statement about the citric acid cycle is: c) It does not operate under anaerobic conditions.

Explanation:

1. The citric acid cycle, also known as the Krebs cycle, is a central metabolic pathway that takes place in the mitochondrial matrix. It involves a series of enzymatic reactions that break down acetyl-CoA derived from the oxidation of carbohydrates, fats, and proteins.
2. The citric acid cycle operates under aerobic conditions, meaning that it requires the presence of oxygen to proceed efficiently. However, it is important to note that the citric acid cycle can be inhibited or slowed down under anaerobic conditions when oxygen is limited or absent, leading to a decrease in its overall activity.
3. Under anaerobic conditions, the electron transport chain, which requires oxygen as the final electron acceptor, cannot function optimally. This can lead to a buildup of certain intermediates of the citric acid cycle and a reduction in the cycle's overall activity. Therefore, while the citric acid cycle primarily operates under aerobic conditions, its functionality can be affected under anaerobic conditions.