Reactants = glucose, oxygen
Products = water, carbon dioxide, Energy in ATP
The oxygen atoms of CO2 originated from glucose and the oxygen atom of H2O is originated from normal oxygen molecule that act as reactant during the break down of glucose by oxidation.
In the above reaction glucose is being reduced to generate CO2 .As a result the oxygen of CO2 is originated from glucose.
The above also deals with the reduction of oxygen to H2O.From that point of view it can be stated that the oxygen atom of H2O originates from molecular oxygen that act as reactant.
The waste products of cellular respiration are carbon dioxide and water.
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