How do cells use oxygen as substance?

Answer 1

Oxygen is the final electron acceptor in the process of oxidative phosphorilation. Oxygen accepts electrons at the end of the electron transfer chain as oxygen's great electronegative charge helps pull the electrons through the chain as protons are pumped into the outer membrane of the mitochondria. As the protons fall down the concentration gradient through the ATP synthase the electrons are coming off the electron transfer chain. The oxygen then takes electrons and two protons forming water which is used in the body.