Final answer:
Photosynthesis and cellular respiration are complementary processes where the products of one serve as the reactants of the other, recycling matter and energy. Photosynthesis converts sunlight into glucose and oxygen, while cellular respiration converts these back into carbon dioxide and water, crafting ATP in the process.
Step-by-step explanation:
Photosynthesis and cellular respiration are considered opposite reactions. The matter is recycled between each process because the products of one reaction are the reactants of the other reaction. During photosynthesis, plants use sunlight to convert carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂). In contrast, cellular respiration uses glucose and oxygen to produce carbon dioxide, water, and ATP, which is the energy currency of the cell.
The two stages of photosynthesis are the light-dependent reactions and the light-independent reactions, or Calvin cycle. The light-dependent reactions absorb sunlight and convert it into chemical energy, while the light-independent reactions use that chemical energy to form glucose from carbon dioxide. Cellular respiration then takes this glucose and breaks it down to produce ATP, releasing carbon dioxide and water as byproducts, thus completing the cycle.