Advanced Placement (AP) Biology Practice Exam

Which of the following is NOT a product of alcoholic fermentation?

1. Carbon dioxide

2. Ethanol

3. Oxygen

4. ATP

The correct answer is: Oxygen

In alcoholic fermentation, the primary products are ethanol and carbon dioxide, along with a certain amount of ATP produced through substrate-level phosphorylation. During this metabolic process, glucose is converted into pyruvate through glycolysis, which is then further metabolized in the absence of oxygen. This results in the formation of ethanol and carbon dioxide, making them key products of the fermentation pathway. Oxygen is not produced in alcoholic fermentation; in fact, the process occurs in anaerobic conditions, meaning it takes place in the absence of oxygen. Therefore, while carbon dioxide, ethanol, and ATP are all generated during fermentation, oxygen is not a byproduct of this process, confirming that it is the correct response in the context of the question.