Answer:
Cyclic electron flow uses just PS I and creates ATP.
Explanation:
Photo-system is known as light-absorbing complexes which are present on the thylakoid membrane of the photosynthetic organisms. A molecule called P700 which is present on PS l and absorb light of approximately 700 nm.
Cyclic electron flow has excited electrons from the photochemical reaction center (P700) in Photo-system I that is passed from Ferrodoxin to the cytochrome complex and back to the photochemical reaction center. Cyclic electron flow only uses PS I and produces ATP, not O2 or NADPH.