Here's why:
* Light-dependent reactions: These reactions occur in the thylakoid membranes of chloroplasts. They use light energy to split water molecules (photolysis). This process releases electrons, protons (H+), and oxygen (O₂).
* Light-independent reactions (Calvin cycle): This stage uses the products of the light-dependent reactions, specifically ATP and NADPH, to convert carbon dioxide into glucose. Water is not directly involved in this stage.
So, while the overall photosynthesis equation shows water as a reactant, it's the light-dependent reactions where water is actually used and broken down.
