How does photosynthesis work? What are the light and dark reactions?
I understand that plants make food from sunlight and CO2. But my teacher mentioned light reactions and the Calvin cycle (dark reactions) and I got completely lost. Can you explain both stages simply?
1 Answer
Photosynthesis has two stages. Light reactions (in thylakoid membrane): Chlorophyll absorbs sunlight and splits water (H2O) into hydrogen and oxygen. The oxygen is released. The energy is used to produce ATP and NADPH. Dark reactions/Calvin cycle (in stroma): Using ATP and NADPH from light reactions, carbon dioxide is fixed (combined with RuBP) and converted into glucose through a series of enzyme-controlled steps. Summary: Light reactions capture energy and release O2. Dark reactions use that energy to build glucose from CO2. Both happen during the day; dark reactions just do not directly need light.
No comments yet — start the discussion.