1. Photosystem II: Light energy is absorbed by chlorophyll in Photosystem II, exciting an electron to a higher energy level. This energized electron is then passed along an electron transport chain.
2. Photosystem I: The electron, after passing through the electron transport chain, arrives at Photosystem I. Here, it absorbs another photon of light, boosting its energy level again. This highly energized electron is then used to create NADPH, a crucial reducing agent in the Calvin cycle.
So, each electron experiences an energy boost in both Photosystem II and Photosystem I during photosynthesis.
