One function of both alcohol fermentation and lactic acid fermentation is to a. oxidize NADH to NAD+. b. reduce NAD + to NADH. c. reduce FAD + to FADH2. d. reduce FADH2 to FAD+. e. none of the above

a. oxidize NADH to NAD+

Explanation:

Alcohol fermentation and lactic acid fermentation share a common step that is glycolysis. Since the organisms or cells that carry out the fermentation lack oxygen, oxidative phosphorylation can not oxidize NADH into NAD+. Without the supply of NAD+, glycolysis cannot occur as NAD + serves as electron acceptor during redox reactions of glycolysis.

To maintain the continuity of glycolysis, alcohol fermentation and lactic acid fermentation oxidize the NADH into NAD + which in turn enter the glycolysis.