Question

During non-cyclic photophosphorylation, electrons are continuously lost from the reaction centre of $PS II$. Which source is used to replace these electrons?

• A. Sunlight
• B. $O_{2}$
• C. $H_{2}O$
• D. $CO_{2}$

Answer 1

Answer: (C)

$H_{2}O$

Answer 2

Non-cydic photophosphorylation is the normal process of photophosphorylation in which the electron expelled by the excited photocentre does not return to it. Non- cydic photophosphorylation is carried out in collaboration of both photosystems $I$ and $II$. Electron released during photolysis of $H_{2}O$ is picked up by photocentre of $PS II$ called $P_{680}$. The same is extruded out when the photocentre absorbs light energy ($hv$). Electrons released during the photolysis of water are immediately accepted by oxidised reaction centre of $PS II$ (i.e., $P_{680}$) through an unknown substance $Z$.