Question

from where does 'cyclic phosphorylation' gets electron since there is no photolysis of water?

Answer 1

Cyclic photophosphorylation occurs under condition of low intensity, wavelength longer than 680 nm and when CO₂ fixation in inhibited. Cyclic photophosphorylation is performd by photosystem I only. Its photocenter P₇₀₀ extrudes an electron with a gain of 23 kcal/mole of energy after absorbing a photon of light.