This is the usual mode of respiration in plants and animals. It takes place in the presence of free oxygen, oxidizing the food completely and releasing the maximum energy, 2827 KJ/mole of glucose. The end-products are carbon
dioxide and water. No toxic substances are formed.
Glucose + Oxygen Aerobic Respiration -> Carbon dioxide + Water + Energy (2827 KJ)
Anaerobic respiration also called fermentation takes place in some bacteria, fungi, and endoparasites. It takes place in the absence of free oxygen, hence, the food is oxidized partially, releasing, a small amount of energy.
Glucose Anaerobic respiration -> Lactic acid + Energy (150 KJ)
IMPORTANCE OF ANAEROBIC RESPIRATION:
As stated earlier, anaerobic respiration takes place in some fungi, bacteria, and endoparasites. Although it yields much less energy in comparison to aerobic respiration, it has an advantage that these organisms can survive without oxygen. Endoparasites especially the gut parasites respire anaerobically as no free oxygen is available.