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Multiple Choice
Which of the following events occurs during the light-dependent reactions of photosynthesis?
A
Splitting of water to release oxygen
B
Synthesis of ribosomes
C
Fixation of carbon dioxide into glucose
D
Conversion of pyruvate to acetyl-CoA
Verified step by step guidance
1
Understand the context: Photosynthesis consists of two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle). The light-dependent reactions occur in the thylakoid membranes of chloroplasts and require light energy.
Identify the key processes in light-dependent reactions: These reactions involve the absorption of light by chlorophyll, the generation of ATP and NADPH, and the splitting of water molecules (photolysis) to release oxygen.
Clarify the incorrect options: Synthesis of ribosomes is unrelated to photosynthesis. Fixation of carbon dioxide into glucose occurs during the Calvin cycle, not the light-dependent reactions. Conversion of pyruvate to acetyl-CoA is part of cellular respiration, not photosynthesis.
Focus on the correct event: The splitting of water (H₂O) during photolysis is a critical event in the light-dependent reactions. This process releases oxygen (O₂) as a byproduct and provides electrons to replenish the photosystem.
Summarize the connection: The splitting of water to release oxygen is a hallmark of the light-dependent reactions, which are essential for producing the energy carriers (ATP and NADPH) needed for the Calvin cycle.