Anaerobic respiration is economically important – many of our foods are produced by microorganisms respiring anaerobically.
Yeast is used to make alcoholic drinks. When yeast cells are reproducing rapidly during beer or wine production, the oxygen runs out. The yeast switches to anaerobic respiration. Ethanol and carbon dioxide are produced.
Yeast can also be used to produce bread. Yeast respires using sugar added to the dough. Bubbles of carbon dioxide make the bread rise. The alcohol that’s produced evaporates as the bread is baked.
Certain plants, and plant cells also respire anaerobically. These include plants that grow in marshes, where oxygen concentrations will be low.