Anaerobic respiration
Without oxygen. respiration does not need oxygen (unlike aerobic respiration). It is the release of a relatively small amount of energy in cells by the breakdown of food substances in the absence of oxygen.
Anaerobic respiration in muscles
Anaerobic respiration happens in muscles during hard exercise.
\(\text{glucose} \rightarrow \text{lactic acid + energy in the form of ATP}\)
A simple sugar used by cells for respiration. is not completely broken down, so less energy is released than during aerobic respiration.
There is a build-up of A toxic chemical produced during anaerobic respiration. in the muscles during vigorous exercise. The lactic acid needs to be Chemical substances are oxidised by the addition of oxygen, removal of hydrogen or the removal of electrons. to carbon dioxide and water later.
The creation of lactic acid (which needs oxygen to be broken down) generates an The amount of extra oxygen required by the body for recovery after vigorous exercise. that needs to be repaid after the exercise stops. This is why we keep on breathing deeply for a few minutes after we have finished exercising.
A short intense burst of exercise such as sprinting will generate energy anaerobically so an oxygen debt will be generated. This is because your body will have released energy without the oxygen it would normally have used performing low intensity exercise like slow, steady running.
The difference between the oxygen the body needs during the sudden sprint and what it actually managed to take in is called oxygen deficit.
Aerobic respiration vs anaerobic respiration
The table summarises some differences between the two types of respiration.
| Aerobic | Anaerobic | |
| Oxygen | Needed | Not needed |
| Glucose breakdown | Complete | Incomplete |
| End product(s) | Carbon dioxide and water | Animal cells - lactic acid. Plant cells and yeast - carbon dioxide and ethanol |
| Energy released | Relatively large amount from each glucose molecule | Relatively small amount from each glucose molecule |
| Oxygen | |
|---|---|
| Aerobic | Needed |
| Anaerobic | Not needed |
| Glucose breakdown | |
|---|---|
| Aerobic | Complete |
| Anaerobic | Incomplete |
| End product(s) | |
|---|---|
| Aerobic | Carbon dioxide and water |
| Anaerobic | Animal cells - lactic acid. Plant cells and yeast - carbon dioxide and ethanol |
| Energy released | |
|---|---|
| Aerobic | Relatively large amount from each glucose molecule |
| Anaerobic | Relatively small amount from each glucose molecule |
Question
Aerobic respiration produces 38 molecules of Stands for 'adenosine triphosphate' which is the high-energy chemical that transfers chemical energy in cells., but anaerobic respiration produces only two molecules of ATP. In comparison to aerobic respiration, what percentage of ATP is produced by anaerobic respiration?
2 ÷ 38 × 100 = 5%