What is the primary role of water in the light-dependent reactions?

The primary role of water in the light-dependent reactions of photosynthesis is to provide electrons and protons. During these reactions, light energy is captured by chlorophyll and used to split water molecules in a process called photolysis. This splitting generates oxygen as a byproduct and releases electrons and protons, which are essential for the production of NADPH and ATP—key energy carriers used in the light-independent reactions (Calvin cycle).

While water does act as a solvent in biological processes, this is not its primary role in the light-dependent reactions. Additionally, water doesn’t directly provide energy; instead, it contributes to the formation of energy-rich molecules through the reactions it undergoes. The production of glucose occurs later in the process during the light-independent reactions, and water itself does not directly create glucose. Therefore, providing electrons and protons is the most accurate interpretation of water's function in this context.