Question

Cellular respiration is the set of metabolic reactions that occur in cells to produce energy in the form of ATP. During cellular respiration, high energy intermediates are created that can then be oxidized to make ATP. During what stage are these intermediates produced?

Answer 1

The question is incomplete. The complete question is:

Question: Cellular respiration is the set of metabolic reactions that occur in cells to produce energy in the form of ATP. During cellular respiration, high energy intermediates are created that can then be oxidized to make ATP. During what stage are these intermediates produced?

a. Glycolysis

b. Oxidative phosphorylation

c. The citric acid cycle

d. Oxidative phosphorylation and citric acid cycle

e. Citric acid cycle and glycolysis

Answer:

e. Citric acid cycle and glycolysis

Explanation:

During the citric acid cycle and glycolysis, NAD+ and FAD+ serve as electron acceptors and are reduced into NADH and FADH2 respectively. The breakdown of one molecule of glucose into pyruvate by glycolysis forms a total of 2 NADH. Oxidation of pyruvate into acetyl CoA in the mitochondrial matrix is catalyzed by enzyme pyruvate dehydrogenase and forms one NADH per pyruvate. Complete oxidation of acetyl CoA into CO2 and H2O by citric acid cycle forms a total of 6 NADH and 2 FADH2.  

Therefore, the citric acid cycle and glycolysis stores the energy released by the breakdown of glucose into NADH and FADH2. Oxidation of these reducing powers by the electron transport chain generates the electrochemical gradient which in turn drives ATP synthesis.