Microbiology Practice Exam

What are the key products of alcohol fermentation?

1. Carbon dioxide and lactic acid

2. Glucose and ATP

3. Ethanol and carbon dioxide

4. Oxygen and glucose

The correct answer is: Ethanol and carbon dioxide

The key products of alcohol fermentation are ethanol and carbon dioxide. During this process, microorganisms such as yeast convert sugars (typically glucose) into energy in the absence of oxygen. This anaerobic pathway breaks down glucose through glycolysis, yielding pyruvate, which is then converted into ethanol and carbon dioxide. Ethanol serves as the alcohol component in beverages, while carbon dioxide is the gas responsible for the bubbles in drinks like beer and champagne. Other options do not accurately reflect the products of alcohol fermentation. For example, lactic acid is produced during lactic acid fermentation, not alcohol fermentation. Glucose and ATP are involved in the process, but they are substrates and energy currency, respectively—ATP is produced during glycolysis, but it is not a final product of fermentation. Lastly, oxygen is not a product of fermentation; rather, it is typically absent in this anaerobic process, and glucose is consumed rather than produced.