Which of the following is a toxic end product commonly produced during anaerobic fermentation in muscle cells?

• A. Glucose
• B. Lactic acid
• C. Carbon dioxide
• D. Ethanol

Answer: (B)

Verified step by step guidance

1. Understand the context: Anaerobic fermentation occurs in muscle cells when oxygen is scarce, such as during intense exercise.
2. Recall that glucose is the starting substrate for glycolysis, not an end product of fermentation.
3. Identify that carbon dioxide and ethanol are typical fermentation products in some microorganisms, but not in human muscle cells.
4. Recognize that in muscle cells, the toxic end product produced during anaerobic fermentation is lactic acid, which accumulates and can cause muscle fatigue.
5. Conclude that lactic acid is the correct answer because it is the toxic end product formed when pyruvate is reduced during anaerobic conditions in muscle cells.