Biology / Unit 11 Bio 2559 short lesson, about 20 seconds
Auxin
Captions available
The idea
Auxin drives cell elongation behind phototropism and gravitropism, controls apical dominance, and promotes root formation, moving through the plant to the side away from a stimulus.
In practice
Auxin accumulating on a stem's shaded side elongates those cells faster, bending the stem toward the light source.
Where people slip
Synthetic auxins serve as herbicides at high concentration, though naturally occurring auxin at normal levels drives ordinary growth.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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