a) Pyruvate is a three-carbon molecule, so two molecules can be produced from each molecule of glucose. In total, from 4 molecules of glucose that enter glycolysis, there will be produced eight molecules of pyruvate.
b) PA becomes Lactic Acid instead of Acetyl CoA in anaerobic respiration (that is in auscense of oxygen), particularly when the cell carries out lactic acid fermentation, which is what can happen in the mitochondria of muscle cells when faced with a very demanding stimulus.
