Question

Which best describes how the photosystems are used in the light-dependent reactions?
Responses

Both processes are used at the same time.
Both processes are used at the same time.

photosystem II is used first then photosystem I
photosystem II is used first then photosystem I

photosystem I is used first then photosystem II
photosystem I is used first then photosystem II

Both processes are used during the light-independent reactions.
Both processes are used during the light-independent reactions.

Answer 1

photosystem II is used first then photosystem I

(Photosynthesis’s light-dependent reactions follow the Z-scheme: PS II absorbs light and drives water splitting and electron flow to PS I, which then helps reduce NADP+.)