Question

Is there something wrong with following the schematic presentation? If yes, correct it so that photosynthesis will be operated.

Answer 1

1. It involves both photosystems- PS-I and PS-II.
2. In this case, the electron transport chain starts with the release of electrons from PS-II.
3. In this chain high energy electrons released from PS-II do not return to PS-II but, after passing through an electron transport chain, reach PS-I, which in turn donates it to reduce NADP⁺ to NADPH.
4. The reduced NADP⁺ (NADPH) is utilized for the reduction of CO₂ in the dark reaction.
5. Electron-deficient PS-II brings about oxidation of water-molecule. Due to this, protons, electrons, and an oxygen atom are released.
6. Electrons are taken up by PS-II itself to return to a reduced state, protons are accepted by NADP⁺ whereas oxygen is released.
7. As in this process, high energy electrons released from PS-II do not return to PS-II and it is accompanied with ATP formation, this is called Non-cyclic photophosphorylation.