Final answer:
An organic compound serves as the final electron acceptor in fermentation, which occurs in the absence of oxygen, allowing the reoxidation of NADH to NAD+ for glycolysis to continue.
Step-by-step explanation:
The molecule that typically serves as the final electron acceptor during fermentation is an organic compound. During fermentation, organisms metabolize sugar in the absence of oxygen, which means they do not use aerobic respiration. In this process, ATP is produced via glycolysis, and NADH must be reoxidized to NAD+ for glycolysis to continue. Fermentation achieves this by transferring electrons from NADH to an organic molecule, such as pyruvate, which then becomes the final electron acceptor and is reduced to form products like lactic acid or ethanol. As fermentation does not involve the use of an electron transport chain (ETC), the organic molecule takes the role as the final electron acceptor rather than oxygen, which is used in aerobic respiration.