Answer:
The correct answer would be A) cell A is in an animal cell in an anaerobic environment and cell B is an animal cell in an aerobic environment.
During lack or absence of oxygen, the animal cells undergo lactic acid fermentation. Under this process, one molecule of glucose is converted into two molecules of pyruvate with a net gain of 2 molecules of ATP and NADH each.
Then, pyruvate is converted into 2 molecules of lactic acid with the utilization of 2 NADH. It creates NAD⁺ lost during glycolysis and thus helps glycolysis to continue.
Thus, the net gain of lactic acid fermentation is 2 ATP only. It is usually observed in muscle cells during exercise.
In contrast, under aerobic conditions glucose is fully oxidized (glycolysis, pyruvate decarboxylation, Krebs cycle, electron transport chain, and chemiosmosis) to produce carbon dioxide, water, and 36-38 ATP.
