Final answer:
Under anaerobic conditions, ATP synthase can hydrolyze ATP, and cells mainly rely on glycolysis for ATP production which yields a net of two ATP molecules per glucose molecule.
Step-by-step explanation:
Under anaerobic conditions, ATP synthase can indeed hydrolyze ATP instead of synthesizing it. Typically, ATP synthase utilizes the proton motive force generated by the electron transport chain to synthesize ATP from ADP and P₁ through oxidative phosphorylation.
However, when oxygen is not available, this process cannot proceed effectively, and cells may resort to ATP hydrolysis to maintain their energy balance. During anaerobic respiration or fermentation, ATP is primarily produced through glycolysis, a process that generates a net yield of two ATP molecules per glucose molecule without the need for oxygen. Notably, under anaerobic conditions, the electron transport chain is not functional, and NADH + H+ is typically reoxidized via other methods such as fermentation, significantly reducing the number of ATP molecules produced.