Difference Between Aerobic Respiration and Fermentation

An important biochemistry topic is ‘respiration,’ through which your body converts nutrients into adenosine triphosphate (ATP) molecules to obtain energy.


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The two different types of respiration are aerobic respiration and fermentation. Another type of respiration is anaerobic respiration which is a little similar to fermentation but still quite different.

Aerobic Respiration vs Fermentation

The difference between aerobic respiration and fermentation is that aerobic respiration takes place in the presence of oxygen as it is required for the breakdown process of its respiratory material, where fermentation does not require the presence of oxygen to break down its respiratory materials. Both of these are used to obtain energy, but their processes are different.

Aerobic Respiration vs Fermentation

Aerobic respiration takes place in the presence of oxygen, generates adenosine triphosphate (ATP) molecules which are used as energy for various bodily functions.

It goes through 3 stages in total. These are the glycolysis, Krebs cycle, and further going through oxidative phosphorylation. It is a form of cellular respiration.

On the other hand, during the process of fermentation, sugar molecules are broken down into simpler compounds to produce ATP molecules to carry biological processes.

It happens in the absence of oxygen. It has 2 steps, namely glycolysis and NADH regeneration which is a process of breaking down pyruvic acid.

Comparison Table

Parameters of ComparisonAerobic RespirationFermentation
OrganismsAnimals and plantsYeast and bacteria mainly
OxygenOxygen is used to break down the respiratory material.Oxygen is not used.
End ProductsCarbon dioxide and water.Ethyl alcohol and carbon dioxide
Respiratory Material.Completely oxidizedNot completely broken.
Formation of WaterIt is formed.It is usually not formed.
ContinuationIt occurs indefinitely.It can’t occur indefinitely.
Energy Formed686 Kcal39-59 Kcal
ATP molecules36 ATP molecules are produced.2 ATP molecules are produced.
StepsIt has 3 steps.It has 2 steps.

What is Aerobic Respiration?

Aerobic respiration uses oxygen to produce energy in the form of ATP molecules by breaking down respiratory material.

It is most common in complex organisms like animals, humans, plants, mammals, etc. It is a type of cellular respiration.

The main end-products formed are carbon dioxide and water. It takes place in the cell’s mitochondrial matrix.

It is very important as it provides enough energy to organisms to perform the essential functions and processes of like.

There are different stages of aerobic respiration. The first stage is glycolysis occurring in the cell’s cytosol.

During glycolysis, glucose is divided into 2 ATP and 2 NADH molecules. Then acetyl coenzyme A is formed.

In the next step, the Krebs cycle (also known as the citric acid cycle) occurs.

During the last stage of aerobic respiration, large quantities of ATP molecules are formed through the transfer of electrons from FADH and NADH. In the end, around 36 ATP molecules are formed through it.

The ATP molecules are produced from ADP and inorganic phosphate with the usage of ATP synthase.

What is Fermentation?

Fermentation is an anaerobic process of breaking down glucose to obtain ATP molecules, which means it can occur in the absence of oxygen.

It occurs in different types of micro-organisms most of the time, like eukaryotes and prokaryotes. It most commonly occurs in yeast and bacteria.

It can also occur in humans but only if the oxygen supply is very limited and there is high demand for energy, for example, during intense workouts.

In humans, fermentation takes place in muscle cells when there is a lack of oxygen. These cells can use up their oxygen if they contract very frequently.

In the absence of oxygen, they go through glycolysis to produce ATP molecules. These muscle cells make pyruvic acid through glucose, after which an enzyme present in muscle cells converts it into pyruvic acid.

In fermentation, glucose is metabolized (i.e., broken down into) pyruvic acid through the process of glycolysis. This pyruvic acid is converted into acetaldehyde.

Then it is further converted into ethyl alcohol. 2 ATP molecules are produced on average through the process of fermentation.

Main Differences Between Aerobic Respiration and Fermentation

  1. Aerobic respiration tends to take place in animals and plants that means in organisms that are multicellular and complex. On the other hand, fermentation occurs in micro-organisms like yeast and bacteria mainly.
  2. Aerobic respiration happens with the help of oxygen which is then used to break the respiratory material down into simpler substances. Fermentation does not use oxygen in the breakdown of its respiratory material.
  3. The process of aerobic respiration produces carbon dioxide and water as a final product, whereas the end products of fermentation consist of at least one organic substance, and inorganic substances may or may not be produced. Ethyl alcohol and carbon dioxide are the most common end products here.
  4. The respiratory material is completely oxidized in aerobic respiration, where it is incompletely broken during the fermentation process.
  5. During aerobic respiration, water is formed, whereas, during fermentation, water isn’t formed.
  6. Aerobic respiration can continue indefinitely, whereas fermentation can’t continue indefinitely since it can lead to less availability of energy and an accumulation of poisonous compounds.
  7. Through aerobic respiration, 686 Kcal of energy per gram mole of glucose are produced, wherein fermentation the energy produced is around 39 to 59 Kcal.
  8. Around 36 ATP molecules are produced during aerobic respiration. On the other hand, only 2 ATP molecules are produced during fermentation.
  9. Aerobic respiration has 3 steps, which are Krebs’ cycle, glycolysis, and oxidative phosphorylation. Fermentation has only 2 steps, which are glycolysis and an incomplete breakdown of pyruvic acid.
Difference Between Aerobic Respiration and Fermentation


  1. https://onlinelibrary.wiley.com/doi/abs/10.1002/jctb.5030320607
  2. https://www.annualreviews.org/doi/abs/10.1146/annurev-food-022811-101255
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