Answer is: 6 molecules of oxygen. First, write down reaction for aerobic respiration: C₆H₁₂O₆ (glucose) + 6O₆ (molecule of oxygen) → 6CO₂ (carbon-dioxide) + 6H₂O (water). Reaction shows that one molecule of glucose react with six molecules of oxygen. Aerobic respiration<span> requires </span>oxygen<span> to create energy.</span>