Plants utilize carbon dioxide in a method identified as photosynthesis. During photosynthesis, plants yield off oxygen as a decay product. Carbon dioxide passes from the atmosphere into the needles of plants by tiny holes in the plant's leaves.
Both Oxygen cycle and carbon cycle acts independently but are subordinate on each other because the carbon cycle provides off oxygen for the oxygen cycle to use, and in return, the oxygen cycle releases carbon dioxide (CO2) which goes back into the carbon cycle. Plants are the principal vehicle by which the oxygen and carbon cycles are correlated.