Final answer:
If glycolysis were disabled in yeast cells, the concentrations of both pyruvate and ethanol would decrease, as they are products of glycolysis and subsequent fermentation respectively.
Step-by-step explanation:
If the process of glycolysis was disabled in yeast cells, the concentration of pyruvate and ethanol would decrease. Pyruvate is a direct product of glycolysis, so if glycolysis does not occur, pyruvate will not be formed. Since pyruvate is a precursor to ethanol in the process of alcoholic fermentation, ethanol levels would also drop without glycolysis. The concentration of NAD, which is an electron carrier, would not necessarily decrease because it is regenerated during fermentation, a process that would also be halted with the inhibition of glycolysis. Oxygen concentration might fluctuate based on environmental conditions rather than being directly affected by the cessation of glycolysis.