Describe how a low-energy electron in water become a high-energy electron on the primary acceptor of a reaction centre.

In photosystem II, the antenna complex absorbs a photon, energizing chlorophyll P680. This excites an electron, which moves to the primary acceptor. P680 becomes positively charged and removes an electron from water, splitting the water molecule. This process repeats, transferring high-energy electrons to the primary acceptor.