1. The final steps in fermentation appear to be unnecessary: the generation of lactate or ethanol does not produce any additional energy for the cell. Explain why cells growing in the absence of oxygen could not simply discard pyruvate a waste product.

2. What, if anything, is wrong with the following statement: “the oxygen consumed during the oxidation of glucose is animal cells returned as part of CO2 to the atmosphere.” How could you support your answer experimentally?