Biology

In the electrons are passed, protons are pumped across the membrane, creating a proton gradient. Oxygen combines with the electrons and protons to form water. Without oxygen, there is no final electron acceptor, and the electron transport chain cannot function. As a result, the electron transport chain will stop first when a cell is deprived of oxygen.

The other option is incorrect:

Glycolysis is the first step in both aerobic and anaerobic respiration. It does not require oxygen and can continue in both aerobic and anaerobic conditions.