Question

reduction of nadp* reduction of primary electron acceptor oxidation of water light absorption reduction of electron transport chain between the two photosystems oxidation of electron transport chain between the two photosystems photosystem ii (ps ii) only photosystem i (ps i) only both ps ii and ps i

Explanation:

• Photosystem II (PS II) only: Oxidation of water occurs in PS II. When PS II absorbs light (light absorption is a common step in both PS II and PS I, but here we focus on the unique for PS II), it splits water molecules. The electrons from water are used to replenish the electrons lost by the reaction - center chlorophyll in PS II.
• Photosystem I (PS I) only: Reduction of \(NADP^{+}\) occurs in PS I. After a series of electron - transfer steps, the electrons are used to reduce \(NADP^{+}\) to \(NADPH\).
• Both PS II and PS I: Light absorption is a process that occurs in both photosystems. Also, the electron - transport chain between the two photosystems has two aspects. The oxidation of the electron - transport chain between the two photosystems is associated with PS II (as PS II donates electrons to the chain), and the reduction of the electron - transport chain between the two photosystems is associated with PS I (as PS I accepts electrons from the chain). The reduction of the primary electron acceptor is a step that occurs in both photosystems (in PS II, the primary electron acceptor accepts electrons from the reaction - center chlorophyll, and in PS I, the primary electron acceptor accepts electrons from the electron - transport chain).

Answer:

• Photosystem II (PS II) only: oxidation of water
• Photosystem I (PS I) only: reduction of \(NADP^{+}\)
• Both PS II and PS I: reduction of primary electron acceptor, light absorption, reduction of electron transport chain between the two photosystems, oxidation of electron transport chain between the two photosystems