Biology / Unit 2 Bio 0335 short lesson, about 20 seconds
Diffusion
Captions available
The idea
Diffusion is the passive movement of a substance from higher to lower concentration until the concentration is equal throughout a space.
In practice
Ammonia vapor released from a bottle spreads outward through a room, thinning as it moves from its point of highest concentration.
Where people slip
Diffusion needs no cellular energy — the concentration gradient itself, not the cell, drives the movement.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Biology