The light reactions of photosynthesis supply the Calvin cycle with which of the following?

• A. Glucose and oxygen
• B. FADH\(_2\) and pyruvate
• C. CO\(_2\) and water
• D. ATP and NADPH

Answer: (D)

Verified step by step guidance

1. Understand the context: Photosynthesis consists of two main stages: the light reactions and the Calvin cycle. The light reactions occur in the thylakoid membranes and convert light energy into chemical energy, while the Calvin cycle occurs in the stroma and uses this chemical energy to synthesize glucose.
2. Identify the products of the light reactions: During the light reactions, light energy is used to split water molecules (photolysis), releasing oxygen as a byproduct. The energy from light is also used to produce ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy carriers.
3. Understand the role of ATP and NADPH: ATP provides the energy needed for the Calvin cycle, while NADPH provides reducing power (electrons) to convert carbon dioxide (CO\(_2\)) into glucose during the cycle.
4. Eliminate incorrect options: Glucose and oxygen are products of photosynthesis but not directly supplied to the Calvin cycle by the light reactions. FADH\(_2\) and pyruvate are involved in cellular respiration, not photosynthesis. CO\(_2\) and water are reactants in photosynthesis, not products of the light reactions.
5. Conclude that ATP and NADPH are the correct answer: The light reactions supply ATP and NADPH to the Calvin cycle, enabling the synthesis of glucose from CO\(_2\).