Final answer:
Continual oxidation of NADH to NAD+ during anoxia is crucial for sustaining ATP production via glycolysis in the absence of oxygen, as it allows the glycolytic pathway to continue by providing the necessary NAD+ for the oxidation of substrates.
Step-by-step explanation:
The continual oxidation of cytosolic NADH to NAD+ is crucial for anaerobic energy production during anoxia stress because it allows glycolysis to continue. In the absence of oxygen, which is the final electron acceptor in aerobic respiration, an organism must regenerate NAD+ to sustain the glycolytic pathway, which provides ATP in an anaerobic condition. The oxidation of NADH to NAD+ is facilitated by fermentation processes such as the conversion of pyruvate to lactate. Without this regeneration of NAD+, glycolysis would halt, as it requires NAD+ to oxidize glyceraldehyde-3-phosphate in the energy payoff phase of glycolysis. During vigorous exercises or strenuous physical work, oxygen can deplete in muscles, leading to anoxia and necessitating anaerobic pathways such as fermentation to produce energy. This process differs from chemiosmosis and oxidative phosphorylation, which occur in the presence of oxygen and generate the majority of ATP during the aerobic catabolism of glucose through the efficiency of the electron transport chain (ETC).