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Multiple Choice
Which of the following best describes the primary functions of Photosystem I and Photosystem II in the light-dependent reactions of photosynthesis in plants?
A
Photosystem I splits water to release oxygen, while Photosystem II produces NADPH.
B
Both Photosystem I and II are responsible only for ATP synthesis.
C
Photosystem II captures light energy to split water and generate ATP, while Photosystem I captures light energy to produce NADPH.
D
Photosystem II fixes carbon dioxide, while Photosystem I generates oxygen.
Verified step by step guidance
1
Understand the context of the problem: Photosynthesis is the process by which plants convert light energy into chemical energy. The light-dependent reactions occur in the thylakoid membranes of chloroplasts and involve two key protein complexes: Photosystem I (PSI) and Photosystem II (PSII).
Clarify the roles of Photosystem II: PSII captures light energy to excite electrons, which are then transferred through the electron transport chain. During this process, water molecules are split (photolysis) to release oxygen, protons, and electrons. The energy from the electron transport chain is used to generate ATP via chemiosmosis.
Clarify the roles of Photosystem I: PSI captures light energy to re-excite electrons that have traveled through the electron transport chain. These high-energy electrons are then used to reduce NADP⁺ to NADPH, which is an essential molecule for the Calvin cycle in the light-independent reactions.
Compare the options provided: Evaluate each statement based on the roles of PSII and PSI. For example, the statement 'Photosystem II captures light energy to split water and generate ATP, while Photosystem I captures light energy to produce NADPH' aligns with the known functions of these systems.
Conclude the reasoning: The correct description of the primary functions of Photosystem I and Photosystem II is that Photosystem II captures light energy to split water and generate ATP, while Photosystem I captures light energy to produce NADPH. This understanding is crucial for grasping the light-dependent reactions of photosynthesis.