Answer by Mimiwhatsup: Photosynthesis will make the glucose that is used in cellular respiration to make ATP(Adenosine Triphosphate). Then the glucose will be then turned back into carbon dioxide, which is also used in photosynthesis (as it is also in the air from the atmosphere). Then water will be broken down to form oxygen during the photosynthesis process, in the cellular respiration the oxygen is combined with hydrogen to form water.