Photosynthesis<span> makes the glucose that is used in </span>cellular respiration<span> to make ATP. The glucose is then turned back </span>into <span>carbon dioxide, which is used in </span>photosynthesis<span>. While water is broken down to form oxygen </span>during photosynthesis, in cellular respiration<span> oxygen is combined </span>with<span> hydrogen to form water. </span><span> </span>