- The importance of oxygen in respiration
- Acts as the final acceptor of hydrogen atoms produced in glycolysis & the Krebs cycle
- Has to remove hydrogen atoms at the end of the chain otherwise there would be a 'back-up' of protons and electrons along the chain and respiration would stop
- Illustrated by the effect of cyanide on repiration > inhibits the final enzyme of the ETC. This enzyme catalyses the addition of H ion & electrons to oxygen to form water.