Final answer:
During the light dependent reaction of photosynthesis, electrons flow from PSII to PSI through the electron transport chain. The excited electrons from PSII are transferred to PSI, where they are used to produce NADPH.
Step-by-step explanation:
The sequence flow of electrons during the light dependent reaction of photosynthesis involves two photosystems, PSII and PSI. When photons strike PSII, pigments pass the light energy to chlorophyll molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PSII to PSI. In PSI, the excited electrons are used to produce NADPH.