Final answer:
Electrons from water replace the missing electron in the reaction center of photosystem II during non-cyclic photophosphorylation in photosynthesis. This process helps generate NADPH and ATP, which are important energy carriers.
Step-by-step explanation:
The missing electron from the reaction center of photosystem II is replenished through a process called non-cyclic photophosphorylation. In this process, electrons from water replace the electrons lost from photosystem II. These electrons are then used to reduce NADP+ to NADPH, which is an important energy carrier in photosynthesis. The electron transport chain moves protons across the thylakoid membrane into the lumen, and ATP synthase uses this electrochemical gradient to produce ATP.