(Photoexcitation/Photoactivation) Step 1 of Light dependant reactions

Question 1

What is a photosystem

and what is it made of

Answer 1

Chlorophyll molecules, accessory pigments and proteins in thylakoid skin/membrane.

Antenna system = Cholorphyll molecules and accessory pigments

Reaction centre = protein complex with chlorophyll a at center

Question 2

Name the two photosystems in chloroplasts

Answer 2

PS1(P700)
and PS2(P680)

Question 3

how do photosystems function

Answer 3

 antenna pigments absorb a photon and transfer the energy to the reaction
center (chlorophyll a molecule)

 an electron from chlorophyll a absorbs the transferred energy (ground state to
excited state)

 this excited electron is then transferred (through redox reactions) to a primary
electron acceptor.

 more electrons come from the splitting of water (photolysis) by Z protein at the
base of PSll (replacing those lost to electron acceptors)

 when H 2 O is split to provide electrons, free H + build up inside the thylakoids
(high [ ])