During the light-dependent reactions of photosynthesis, water molecules are split by the oxygen-evolving complex associated with Photosystem II. What is the primary role of water in this process?

Core Concept

When light energy excites electrons in the reaction center chlorophyll (P680) of Photosystem II, those high-energy electrons are passed to the primary electron acceptor. Water is split (photolysis) to donate replacement electrons to the oxidized chlorophyll, releasing O2 and H+ as byproducts.