Here's how it works:
* Light-dependent reactions: Sunlight is absorbed by chlorophyll, which excites electrons. These high-energy electrons are then passed along an electron transport chain.
* Water splitting: To replace the electrons lost by chlorophyll, water molecules are split. This process, called photolysis, releases oxygen (O₂) as a byproduct and provides electrons (e⁻) that continue the electron transport chain.
The overall reaction is:
2H₂O → 4H⁺ + 4e⁻ + O₂
So, the electrons that drive photosynthesis come from the splitting of water molecules.
