Question

Distinguish between Cyclic photophosphorylation and Non-cyclic photophosphorylation.

Answer 1

	Cyclic photophosphorylation	Non-cyclic photophosphorylation
1.	Only Photosystem I is involved.	Both photosystems I and II are involved.
2.	It is not associated with the photolysis of water, and so, oxygen is not liberated.	It is associated with the photolysis of water and the liberation of oxygen.
3.	It involves only ATP synthesis.	It involves ATP synthesis and the production of NADPH.
4.	It takes place under low light intensity, anaerobic conditions, or when CO2 availability is less.	It takes place under optimum light, aerobic conditions, and the presence of CO2.
5.	It occurs mostly in stromal or intergranal thylakoids.	It occurs in the granal thylakoids.
6.	ATP synthesis is not affected by DCMU.	DCMU inhibits non-cyclic photo-phosphorylation.