Photosynthesis in Depth
This lesson connects molecular mechanisms, cell behavior and biological evidence. Instead of memorizing isolated terms, follow what changes, what is measured, where the process occurs and why the outcome matters to a living system.
Big idea
Chlorophyll absorbs light in thylakoids, and water is split to replace electrons, releasing oxygen. Electron flow pumps protons into the thylakoid space and reduces NADP+ to NADPH.
Learning goals
- Light absorption and photolysis: Chlorophyll absorbs light in thylakoids, and water is split to replace electrons, releasing oxygen.
- Photosynthetic electron transport: Electron flow pumps protons into the thylakoid space and reduces NADP+ to NADPH.
- Photophosphorylation: Protons return through ATP synthase, producing ATP in the chloroplast.
- Calvin cycle: RuBisCO fixes carbon dioxide, and cycle reactions use ATP and NADPH to produce G3P.
- Limiting factors: Light intensity, carbon dioxide, temperature and water can limit the overall photosynthetic rate.
Core concepts
1. Light absorption and photolysis
Chlorophyll absorbs light in thylakoids, and water is split to replace electrons, releasing oxygen.
Observation or application: Illuminated photosystem II transfers excited electrons and releases oxygen from water.
2. Photosynthetic electron transport
Electron flow pumps protons into the thylakoid space and reduces NADP+ to NADPH.
Observation or application: A proton gradient and NADPH store energy from the light-dependent reactions.