Question

multiple choice question
what happens to pyruvic acid in the presence of oxygen?

it enters the mitochondria and is oxidized by aerobic respiration.
it is converted to glucose, which then undergoes glycolysis.
it accepts electrons from nadh and is reduced to lactic acid.
it enters the blood stream and is transported to the liver.

Explanation:

To solve this, we analyze each option:

• Option 1: In aerobic conditions (presence of oxygen), pyruvic acid enters the mitochondria and undergoes aerobic respiration (Krebs cycle and electron transport chain) to produce more ATP. This is correct.
• Option 2: Pyruvic acid isn't converted to glucose for glycolysis in presence of oxygen; glycolysis precedes pyruvate formation, and aerobic respiration follows. Incorrect.
• Option 3: Reduction to lactic acid is anaerobic (no oxygen) fermentation. Incorrect.
• Option 4: Pyruvic acid doesn't enter the bloodstream to the liver in presence of oxygen; it enters mitochondria for aerobic respiration. Incorrect.

Answer:

A. It enters the mitochondria and is oxidized by aerobic respiration.