What product is formed when pyruvate undergoes fermentation?

• A. Acetyl CoA
• B. Lactate
• C. Ethyl alcohol
• D. Glucose

Answer: (B)

When pyruvate undergoes fermentation, one of the primary products formed is lactate, especially in anaerobic conditions such as during strenuous exercise in humans. This process is referred to as lactic acid fermentation. During fermentation, pyruvate generated from glycolysis is reduced to lactate, allowing for the regeneration of NAD+, which is necessary for the glycolytic pathway to continue functioning in the absence of oxygen.

In comparison, under different fermentation conditions, such as in yeast, pyruvate can be converted into ethyl alcohol and carbon dioxide through alcoholic fermentation. However, the specific context of this question regarding pyruvate fermentation in general points towards lactate as the product most commonly associated with anaerobic respiration in animals. Other products like acetyl CoA and glucose are not direct products of fermentation from pyruvate; acetyl CoA is involved in aerobic metabolism, while glucose is a precursor rather than a product in this scenario. Thus, lactate is the correct and direct result of pyruvate fermentation in many physiological contexts.