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nimoloth in interacademia


Science folks, I have a question. Since the Sun's emission peaks primarily in the green wavelengths, why does chlorophyll not absorb green? It has absorption peaks in red and blue, but reflects most of what's in between. Surely evolution would have led to the development of a molecule that was most sensitive to green, since that's what there is most of?

My best guess is that if it could absorb green, it would have a chemical structure that would prevent it doing whatever else it does, i.e. plants wouldn't be able to exist with it like that.

Are there any biologists here that can help me out?


I recently (half)read a book on colours and pigments. It's a little light on detail, but it says that only red and blue light are actually used in the photosynthesis process, and so the green light - having no use to the plant - is reflected. I guess this is because the processes that convert water and carbon-dioxide into oxygen and glucose don't need stimulation in the green photon region. In which case, the fact that plants are green and the sun peaks in the green is a coincidence and plants/chlorophyl evolved as they did due to the composition of the atmosphere rather than the solar spectrum.

Also, is it not true that the sun would have been less bright back when plants start evolving? I'm just slevering shite here but I'm sure the sun was cooler when younger(?) so the peak would have been shifted >500nm? Although that was probably way before plant evolution...?