Biology / Unit 11 Bio 2551 short lesson, about 20 seconds
Phototropism: the Phytochrome and Blue-Light Systems
Captions available
The idea
Phototropism, a plant's directional bending toward or away from light, is mediated by blue-light receptors, phototropins, distinct from the red/far-red phytochrome system governing germination and flowering timing.
In practice
A windowsill seedling bends toward light as blue-light receptors trigger faster elongation on its shaded side.
Where people slip
Phytochrome and phototropin are separate systems — one tracks red/far-red light for timing, the other blue light for direction.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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