The reactants and the products of photosynthesis and cellular respiration are the same but switched around.
Explanation:
For photosynthesis light energy, carbon dioxide, water are needed to create glucose and the<em> waste product</em> is oxygen. But for cellular respiration the things needed to create energy to move around are oxygen and glucose. Mitochondria (aka the powerhouse of the cell) breaks down the glucose to make ATP energy (Adenosine Triphosphate). Plants store some leftover oxygen for cellular respiration. So basically, photosynthesis and cellular respiration kinda depend on each other.