Oxygen
Oxygen is the final electron acceptor, no part of the process - from the Krebs Cycle through the electron transport chain- can happen without oxygen. Aerobic respiration is complete
Formation of the Earth's Atmosphere. The early Earth was very different from our Earth today. The early Earth experienced frequent impacts from asteroids and meteorites and had much more frequent volcanic eruptions. There was no life on Earth for the first billion years because the atmosphere was not suitable for life.
For most organism (animals and humans) glucogen is stored in the liver. Glycogen in basically a bundle of glucose. This is like storing energy as the glucogen can be changed back into glucose by a hormone by Glucagon. It breaks down the insoluble glycogen into glucose that can be used in respiration which creates energy.
Respiraton
Glucose+ Oxygen = Water + Carbon Dioxide + ENERGY
