Photosystem II is the first complex involved in the light-dependent reactions in photosynthesis.
It is named photosystem II because it was the first photosystem to be discovered.
Photosystem II is a huge complex of proteins (sometimes called a supercomplex) found in the thylakoid membrane of chloroplasts.
Photosystem II captures energy from photons of light (from the sun) to oxidise two molecules of water to form molecular oxygen. This releases electrons and hydrogen ions.
When light is absorbed by one of the many pigments (chlorophyll), energy is passed from pigment to pigment until it reaches the reaction center. There, energy is transferred to a special pair of core chlorophyll pigment molecules, called P680, raising an electron to a high energy state.
The high energy electron is passed to an acceptor molecule and replaced with an electron from water. This splitting of water forms oxygen
Electrons travel down an electron transport chain, driving ATP production and arriving at photosystem I, which is where more energy and ATP are produced to fuel the rest of the photosynthesis reactions
