Lactic acid accumulation occurs due to insufficient oxygen.

Lactic acid accumulation occurs due to insufficient oxygen.

• A. Excess oxygen
• B. Adequate oxygen
• C. Lack of oxygen
• D. High pH

Answer: (C)

When oxygen is limited, cells can't fully run the aerobic pathways, so they switch to anaerobic glycolysis. This means glucose is broken down to pyruvate, and pyruvate is then converted to lactate to regenerate NAD+, allowing glycolysis to continue and produce some ATP without oxygen. That lactate accumulates in the muscles and blood, which is why lactic acid buildup occurs under insufficient oxygen. If oxygen is plentiful, pyruvate goes into the mitochondria for aerobic respiration, producing more ATP and not accumulating lactate. A high pH reflects alkaline conditions and isn’t tied to lactate buildup, which is associated with increased acidity.

When oxygen is limited, cells can't fully run the aerobic pathways, so they switch to anaerobic glycolysis. This means glucose is broken down to pyruvate, and pyruvate is then converted to lactate to regenerate NAD+, allowing glycolysis to continue and produce some ATP without oxygen. That lactate accumulates in the muscles and blood, which is why lactic acid buildup occurs under insufficient oxygen. If oxygen is plentiful, pyruvate goes into the mitochondria for aerobic respiration, producing more ATP and not accumulating lactate. A high pH reflects alkaline conditions and isn’t tied to lactate buildup, which is associated with increased acidity.