Biology / Unit 2 Bio 0358 short lesson, about 20 seconds
Active Transport
Captions available
The idea
Active transport moves a substance against its concentration gradient, low to high, requiring the cell to spend energy, usually from ATP.
In practice
A cell importing a nutrient already more concentrated inside than outside must spend ATP to force that import.
Where people slip
Active transport is defined by direction relative to the gradient — facilitated transport also uses proteins but spends no energy.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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