Why do plants need green light specifically? Could plants theoretically photosynthesize different wavelengths? Thank you for reading and have a good day.
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To add to the others, the reason chlorophyl reflects green light while absorbing red and blue is because of a fluke of evolution. Eons ago, the main photosynthesizers in the oceans used rhodopsin which uses green light and reflects red and blue because that’s the group of wavelengths that the sun shines strongest in. When a new kind of photosynthesis evolved, it had to be competitive with the purple rhodopsin users. So it was tuned to using red and green light that rhodopsin didn’t use. As it happens, this new kind of photosynthesis generated a powerful toxin as a byproduct. The new cyanobacteria had a slightly better ability to withstand exposure to this toxin than the old bacteria that used rhodopsin since they were already surrounded by it, so they gradually replaced the old guard. By then, though, chlorophyl was already optimized to using red and blue wavelengths and couldn’t be changed to also incorporate green.
The deadly toxin, by the way, was oxygen. So harmful was it back then that one of the names for the event is the Oxygen Catastrophe. It’s still highly toxic to life, but most living things nowadays have developed enough defences against it that they can not only thrive in high concentrations, but even metabolize it for energy.
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