Which of the following events occurs during the light reactions of photosynthesis?

• A. Splitting of water molecules to release oxygen
• B. Reduction of NADP\(^+\) to NADPH
• C. Fixation of carbon dioxide into glucose
• D. Conversion of glucose to pyruvate

Answer: (A)

Verified step by step guidance

1. Understand that the light reactions of photosynthesis occur in the thylakoid membranes of chloroplasts and are responsible for converting light energy into chemical energy in the form of ATP and NADPH.
2. Recognize that during the light reactions, water molecules (H extsubscript{2}O) are split in a process called photolysis. This releases oxygen (O extsubscript{2}) as a byproduct, along with protons (H extsuperscript{+}) and electrons.
3. Note that the electrons released from water are transferred through the electron transport chain, where they help reduce NADP extsuperscript{+} to NADPH. This is a key event in the light reactions.
4. Clarify that the fixation of carbon dioxide into glucose and the conversion of glucose to pyruvate are part of the Calvin cycle and cellular respiration, respectively, and do not occur during the light reactions.
5. Conclude that the correct events associated with the light reactions are the splitting of water molecules to release oxygen and the reduction of NADP extsuperscript{+} to NADPH.