A ATP is produced

B Photosystem I reaction center is active

C Electron transport occurs in the photosynthetic membranes

D Light energy is utilized

E NADPH is formed

Cyclic photo- phosphorylation requires photosystem I, but not photosystem II. Light-dependent electron transport occurs in the thylakoid membranes, where electrons follow a cyclic pathway, returning to the photosystem I reaction center. The energy of this electron transport results in a H+ gradient formation, the energy source for ATP synthesis. ATP is formed from ADP and Pi, but NADP+ is not reduced.