Let me share with you a Comparison between Photosystem I and Photosystem II.
| Aspect | Photosystem I | Photosystem II |
| Abbreviation | PS I | PS II |
| Location | Thylakoid membrane of chloroplasts | Thylakoid membrane of chloroplasts |
| Wavelength of light absorption | 700 nm | 680 nm |
| Reaction center | P700 | P680 |
| Electron donor | Receives electrons from the electron transport chain after Photosystem II. | Extracts electrons from water molecules during the process of photolysis. |
| Electron Transport | Electrons are transferred to ferredoxin and then to NADP+ reductase, ultimately reducing NADP+ to NADPH. | Electrons are passed through a series of carriers, including plastoquinone and cytochrome b6f, and ultimately contribute to the reduction of plastoquinone. |
| Significance | Contributes to the production of NADPH. | Generates ATP through the proton gradient established during electron transport. |
| Photoprotection | Generally less susceptible to photodamage compared to Photosystem II. | More vulnerable to photodamage, and some plants have evolved protective mechanisms, such as non-photochemical quenching. |
| Participation in cyclic Photophosphorylation | Participates in cyclic electron flow, producing ATP without generating NADPH. | Not directly involved in cyclic photophosphorylation. |