| Aerobic respiration | Anaerobic respiration |
| It occurs in the presence of O2. | It occurs in the absence of O2. |
| It involves the exchange of gases between the organism and the outside environment. | Exchange of gases is absent. |
| It occurs in cytoplasm and mitochondria. | It occurs only in cytoplasm. |
| It always releases CO2 and H2O. | End products vary. |
Anaerobic respiration occurs in the roots of some waterlogged plants, some parasitic worms, animal muscles, and some micro-organisms such as yeasts.
