Answer:
Some human cells, such as nerve cells, are restricted to aerobic respiration to recycle NADH and FADH2. If these cells are deprived of oxygen, then oxidative phosphorylation would come to a halt because there wouldn't be any oxygen to pull the electrons down the transport chain.
Step-by-step explanation:
Aerobic cells like human nerve cells can only perform oxidative phosphorylation (and, therefore, ATP production) when in presence of oxygen, otherwise the process is stopped.
Fermentation is an anaerobic process that can only be performed by yeast cells, bacteria, and muscle cells in animals, allowing glucose to be metabolized even when there's no oxygen in the environment.