During high-intensity exercise, mammalian skeletal muscle cells experience temporary hypoxic conditions and shift primarily to anaerobic respiration. Which of the following statements correctly explains the biochemical basis for the differences in ATP yield and pathway activity under these conditions?
The reduction of pyruvate to lactate in the cytoplasm directly couples with the phosphorylation of ADP to ATP, compensating for the inactive Link reaction.
Without oxygen acting as the terminal electron acceptor, the electron transport chain cannot oxidize reduced coenzymes, halting the Link reaction and Krebs cycle, and restricting ATP production to glycolysis.
In hypoxic conditions, glycolysis is inhibited because the active transport of glucose into the muscle fiber becomes dependent on ATP-driven pump mechanisms.
Anaerobic respiration has a lower ATP yield because the regeneration of NAD+\text{NAD}^+NAD+ from reduced NAD during lactate production is an energy-consuming reaction that hydrolyzes ATP.
