Question

Give scientific reason.

Oxygen is necessary for complete oxidation of glucose. 

Answer 1

1. Glucose can be oxidized in two pathways i.e. aerobic and anaerobic respiration. 
2. A molecule of glucose is completely oxidized in aerobic respiration (i.e. in the presence of oxygen) to form \[\ce{CO2, H2O,}\] and energy (38 ATP), via. three steps namely glycolysis, Krebs cycle, and electron transfer chain.
3. 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 the complete oxidation of glucose.