What is the main product of the light-dependent reactions of photosynthesis?

• A. Carbon dioxide
• B. ATP and NADPH
• C. Glucose
• D. Oxygen only

Answer: (B)

Verified step by step guidance

1. Understand the context: The light-dependent reactions of photosynthesis occur in the thylakoid membranes of chloroplasts and are the first stage of photosynthesis. These reactions convert light energy into chemical energy.
2. Identify the key inputs: The light-dependent reactions require light energy, water (H₂O), and the presence of chlorophyll to capture light energy.
3. Determine the key outputs: The main products of the light-dependent reactions are ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy carriers. Additionally, oxygen (O₂) is released as a byproduct when water is split.
4. Clarify the role of ATP and NADPH: These molecules are used in the subsequent light-independent reactions (Calvin cycle) to synthesize glucose from carbon dioxide (CO₂).
5. Eliminate incorrect options: Carbon dioxide and glucose are not products of the light-dependent reactions. Oxygen is a byproduct, but the main products are ATP and NADPH.