Which of the following is not true regarding lactic acid build-up during anaerobic respiration?

• A. Lactic acid build-up can lead to muscle fatigue and soreness.
• B. Lactic acid is converted back to pyruvate when oxygen becomes available.
• C. Lactic acid build-up is a result of oxygen being present in the cells.
• D. Lactic acid build-up occurs in muscle cells during intense exercise.

Answer: (C)

Verified step by step guidance

1. Understand the context of anaerobic respiration: During intense exercise, oxygen supply to muscle cells can be insufficient, leading to anaerobic respiration where glucose is converted to lactic acid.
2. Recognize the role of lactic acid: Lactic acid build-up can lead to muscle fatigue and soreness, which is a common experience during intense physical activity.
3. Identify the conversion process: When oxygen becomes available again, lactic acid can be converted back to pyruvate, which can then enter the aerobic respiration pathway.
4. Clarify the misconception: Lactic acid build-up is not a result of oxygen being present; rather, it occurs due to the lack of oxygen, forcing cells to rely on anaerobic pathways.
5. Summarize the conditions: Lactic acid accumulation typically occurs in muscle cells during periods of intense exercise when oxygen is scarce, not when it is abundant.