Question

In PS II, the reaction centre is

• A. P700
• B. P600
• C. P680
• D. P780

Answer 1

The correct option is C P680

Photosystem I (PS I) is a photosynthetic pigment system. It contains some electron carriers. It is located on both the non-appressed part of grana thylakoids and stroma thylakoids. It consists of a photocentre, light harvesting complexes (LHC I) and a few electron carriers. The reaction centre is formed by a chlorophyll ‘a’ molecule called P700. There is not 1, but many of these reaction centres. LHCs contain chlorophyll ‘b’ and carotenoids. It contains $A_0$ (a modified chlorophyll molecule), $A_1$, Fe-S (iron-sulphur) centres, ferredoxin (Fd).
Photosystem II (PS II) is another photosynthetic pigment system. It contains some electron carriers. It is located in the appressed part of grana thylakoids. It has chlorophyll ‘a’, ‘b’ and carotenoids. It consists of a photocentre, oxygen evolving complex, light harvesting complexes (LHC II) and some electron carriers. The reaction centre is formed by a chlorophyll ‘a’ molecule called P680. There is not 1, but many of these reaction centres. LHCs contain chlorophyll ‘b’ and carotenoids. Other components are, pheophytin, plastoquinone (PQ) and plastocyanin (PC).