Electron transport is the final stage of aerobic respiration.
Aerobic respiration is an oxidative process which uses oxygen as a final electron acceptor.
Oxygen is used as an electron acceptor in respiration.
What is oxygen used as in respiration?

  heat produced
  electron acceptor
  photosynthesis
  Chemical energy
  preventing heat transfer
  Veins and arteries.
  it keeps an organism warm
  It helps them survive