2.11 - Photosystems

Question 1

Where are pigments found?

Answer 1

They are found in the thylakoid membrane.
Clusters of these are called photosystems.

Question 2

Where are the accessory pigments found?

Answer 2

They are found in the antenna complex of the photosystem
(which are around the reaction centre)

Question 3

Where is chlorophyll-a located?

Answer 3

It’s located in the reaction centre.

Question 4

Describes what occurs in a photosystem when a photon of light hits it?

Answer 4

• when light reaches a photosystem, the energy is absorbed by a pigments (typically in the antenna complex)
• this brings an electron out of it’s ground state into an excited state, which causes to jump out and onto another pigment (photoexcitation)
• the energized electron keeps jumping around until it reaches chlorophyll-a
• at chlorophyll-a, it passes it on to a primary electron acceptor
• the chlorophyll becomes oxidized, and the electrons that have been lost, must be replaced by the splitting of H2O which releases O as a by-product