The oxygen cycle, on the other hand, is almost the same as the carbon cycle yet it follows the opposite direction, as depicted in the chemical reaction below: 6CO2 + 6H2O + energy > C6H12O6 + 6O2 The oxygen and carbon cycles are thus related because each of these biogeochemical cycles requires the presence of the other molecule. In the case of the global oxygen cycle, enough carbon dioxide should be available in order for plants to continuously perform photosynthesis that will generate simple sugars such as glucose and the essential atmospheric gas oxygen (Cloud and Gibor, 1970).
As for the case of the carbon cycle, it is also necessary the ample oxygen gas be present at all times, which in turns originates from the oxygen cycle, in order for this cycle to proceed. Should there be a situation wherein carbon dioxide or oxygen is insufficient in the atmosphere, the other biogeochemical cycle is affected and may possibly be prevented from completing the reaction.
Reference Cloud P and Gibor A (1970): The oxygen cycle. Scientific American 122:110-123.