Final answer:
During photosynthesis, electrons flow from water to NADP+ in photosystem II and then from photosystem II to photosystem I through the thylakoid membrane. This flow of electrons is driven by light and produces NADPH and ATP.
Step-by-step explanation:
The flow of electrons during the process of photosynthesis occurs in the thylakoid membrane of the chloroplast. It involves two steps: the movement of electrons from water to NADP+ in photosystem II (PSII) and the transfer of electrons from PSII to photosystem I (PSI). The energy from light is crucial in making these electron transfers more likely through redox reactions. As the electrons flow through the membrane, they create a proton gradient, which can be used to synthesize ATP. This group of reactions, powered by light and producing NADPH and ATP, is known as the light reactions of photosynthesis.