We are air-breathing organisms; we use oxygen to release chemical energy from the food we eat during the process of respiration.
What happens though when we use up oxygen so quickly that you cannot replace it fast enough?
The ladies in the picture to the right show an example of when oxygen is used up quickly. Do their cells stop working?
Also, what about microorganisms, such as yeast, that do not always have oxygen available? How do they extract energy from food without oxygen present?
Source: Left: Fleischmann's Active Dry Yeast Jar, Hannaford.com; Right: Baker's Yeast, Mdidea.com
Anaerobic respiration is a way for an organism to produce usable energy without the involvement of oxygen.