When do muscle cells transition to anaerobic fermentation to generate ATP by glycolysis?

• A. When carbon dioxide levels in the blood are low
• B. When glucose levels in the blood are high
• C. When oxygen supply is insufficient to meet energy demands
• D. When ATP levels in the cell are abundant

Answer: (C)

Verified step by step guidance

1. Understand the context: Muscle cells primarily generate ATP through aerobic respiration, which requires oxygen. However, when oxygen supply is insufficient, they switch to anaerobic fermentation to meet energy demands.
2. Recall the process of glycolysis: Glycolysis is the first step in both aerobic and anaerobic respiration. It breaks down glucose into pyruvate, generating a small amount of ATP. In anaerobic conditions, pyruvate is converted into lactate instead of entering the mitochondria for further processing.
3. Identify the trigger for anaerobic fermentation: Muscle cells transition to anaerobic fermentation when oxygen levels are too low to support aerobic respiration. This typically happens during intense physical activity when energy demands exceed the oxygen supply.
4. Clarify why other options are incorrect: Low carbon dioxide levels in the blood do not directly affect the transition to anaerobic fermentation. High glucose levels in the blood provide fuel for glycolysis but do not determine whether the process is aerobic or anaerobic. Abundant ATP levels in the cell would reduce the need for further ATP production, making anaerobic fermentation unnecessary.
5. Summarize the correct answer: Muscle cells transition to anaerobic fermentation to generate ATP by glycolysis when oxygen supply is insufficient to meet energy demands.