Final answer:
The pathway of electron transfer from photosystem II to photosystem I in light-dependent reactions involves the excitation of electrons by photons, their movement along an electron transport chain, and the creation of an electrochemical gradient.
Step-by-step explanation:
The pathway of electron transfer from photosystem II to photosystem I in light-dependent reactions involves several steps. After a photon hits a chlorophyll molecule in photosystem II, it excites an electron, causing it to break free. The electron is then transferred to a series of proteins called the electron transport chain, which fuels membrane pumps that move hydrogen ions against their concentration gradient. The energy from the electron is used to create an electrochemical gradient, and the electron is eventually accepted by a pigment molecule in photosystem I.