Question

how would anaerobic conditions (when no o₂ is present) affect the rate of electron transport and atp production during oxidative phosphorylation? (note that you should not consider the effect on atp synthesis in glycolysis or the citric acid cycle.)
both electron transport and atp synthesis would stop.
electron transport would stop but atp synthesis would be unaffected.
neither electron transport nor atp synthesis would be affected.
electron transport would be unaffected but atp synthesis would stop.

Explanation:

In oxidative phosphorylation, oxygen (\(O_2\)) acts as the final electron acceptor in the electron - transport chain. Without \(O_2\), electrons cannot be passed along the electron - transport chain (so electron transport stops). ATP synthesis in oxidative phosphorylation is directly coupled to the electron - transport chain (through the proton - motive force generated by electron transport). If electron transport stops, there is no proton - motive force to drive ATP synthesis by ATP synthase.

Answer:

Both electron transport and ATP synthesis would stop.