Here's why:
* Photo- refers to light.
* Phosphorylation refers to the addition of a phosphate group.
* ATP (adenosine triphosphate) is the energy currency of cells.
Photophosphorylation is a process that occurs during the light-dependent reactions of photosynthesis. Chlorophyll absorbs light energy, which is used to create a proton gradient across the thylakoid membrane in chloroplasts. This gradient drives the synthesis of ATP.