Question

D Question 19 2 pts Which of the following statements best describes the primary role played by oxygen in cellular respiration? It yields energy in the form of ATP as it is passed down the electron transport chain. It serves as an acceptor for carbon, forming CO2 in the citric acid cycle. It oxidizes glucose to form two molecules of pyruvate. It serves as the final acceptor for electrons from the electron transport chain. Question 20 2 pts Which of the following statements about NAD is true? NAD'is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. In the absence of NAD*, glycolysis can still function. NAD can donate electrons for use in oxidative phosphorylation NAD has more chemical energy than NADH.

Answer 1

19. In cellular respiration,the oxygen serves as the final acceptor for electrons from the electron transport chain.At the final stage the oxygen combines with electrons and hydrogen ions to form water.

20. NAD+ is reduced to NADH during glycolysis , pyruvate oxidation and citric acid cycle. When the process of glycolysis is takingplace,the concentration of NAD+ is slowly decreasing.Thus the NADH undergoes oxydation in the presence of oxygen, to give back the NAD+. Hence the process continues.

But in some situations,there will be no oxygen.At that time Pyruvate undergoes a processcalled Fermentation.Fermentation is the process of oxidising a molecule in the absence of Oxygen.this helpsin replenishing NAD+ which further promotes the glycolysis.