1. a photon strikes a pigment molecule in PS II, boosting one of its electrons to a higher energy level. As this electron falls back, it boosts a nearby electron in a nearby pigment molecule, "passing the charge" until it reaches the P680 pair of chlorophyll molecules. The electron then gets transferred to the primary electron receptor. An enzyme catalyzes the splitting of a water molecule into 2e-, 2H+, and one O. the e- replace the electron hole in P680. O combine together & form O2. Each electron then passes from PS II to PS I via electron transport chain. The exergonic fall of e- to a lower energy level provides energy for the synthesis of ATP: As electrons pass through the cytc, the pumping of H+ builds a proton gradient that is used in chemiosmosis. The same process then occurs in PS I with P700 molecules. Then, e- pass down a second electron transport chain but no proton gradient is generated so no ATP is made. Finally the e- are stored in NADPH.