* Sunlight: The energy source for the entire process.
* Water (H₂O): Provides electrons and protons (H+) to drive the electron transport chain.
* Chlorophyll: The pigment that absorbs light energy. It's found in the thylakoid membranes of chloroplasts.
* Electron carriers (NADP+): Accepts electrons from the electron transport chain to become NADPH, a high-energy electron carrier used in the Calvin cycle.
* ADP (adenosine diphosphate) and inorganic phosphate (Pi): Combined to form ATP (adenosine triphosphate), the energy currency of the cell.
The light reaction essentially converts light energy into chemical energy in the form of ATP and NADPH, which are then used in the Calvin cycle (dark reaction) to fix carbon dioxide and produce sugar.
