Give scientific reasons:
Oxygen is necessary for complete oxidation of glucose.

Explanation

i. A molecule of glucose is completely oxidized in aerobic respiration (i.e., in the presence of oxygen) to form `CO_(2), H_(2)O` and energy ( 38 ATP), via, three steps namely glycolysis , Krebs cycle and electron transfer chain.
ii. However, in anaerobic respiration ( i.e., in absence of oxygen), glucose is incompletely oxidized via. glycolysis and fermentation , resulting in the formation of organic acids or alcohols and lesser amount of energy is obtained.
Hence, oxygen is necessary for complete oxidation of glucose.