READ: Anaerobic and Aerobic Respiration

Aerobic vs. Anaerobic Respiration: A Comparison

Aerobic vs. Anaerobic Respiration: A Comparison

Aerobic respiration evolved after oxygen was added to Earth’s atmosphere. This type of respiration is useful today because the atmosphere is now 21% oxygen. However, some anaerobic organisms that evolved before the atmosphere contained oxygen have survived to the present. Therefore, anaerobic respiration must also have advantages.

Advantages of Aerobic Respiration

A major advantage of aerobic respiration is the amount of energy it releases. Without oxygen, organisms can just split glucose into two molecules of pyruvate. This releases only enough energy to make two ATP molecules. With oxygen, organisms can break down glucose all the way to carbon dioxide. This releases enough energy to produce up to 38 ATP molecules. Thus, aerobic respiration releases much more energy than anaerobic respiration. The amount of energy produced by aerobic respiration may explain why aerobic organisms came to dominate life on Earth. It may also explain how organisms were able to become multicellular and increase in size.

Advantages of Anaerobic Respiration

One advantage of anaerobic respiration is obvious. It lets organisms live in places where there is little or no oxygen. Such places include deep water, soil, and the digestive tracts of animals such as humans (see Figure below.)

E. coli bacteria are anaerobic bacteria that live in the human digestive tract.

Another advantage of anaerobic respiration is its speed. It produces ATP very quickly. For example, it lets your muscles get the energy they need for short bursts of intense activity (see Figure below). Aerobic respiration, on the other hand, produces ATP more slowly.

The muscles of these hurdlers need to use anaerobic respiration for energy. It gives them the energy they need for the short-term, intense activity of this sport.

Lesson Summary

  • Fermentation is a way of making ATP from glucose without oxygen. There are two types of fermentation: lactic acid fermentation and alcoholic fermentation.
  • Lactic acid fermentation changes pyruvic acid to lactic acid and forms NAD+. The NAD+ allows glycolysis to continue so it can make more ATP.
  • Alcohol fermentation changes pyruvic acid to ethanol and carbon dioxide and forms NAD+. Again, the NAD+ allows glycolysis to keep making ATP.
  • Aerobic respiration produces much more ATP than anaerobic respiration. However, anaerobic respiration occurs more quickly.

CK-12 Foundation, Biology.