Active transport
Active transport
- Active transport moves particles against the concentration gradient (low → high).
- Because it is "uphill", it needs energy from respiration.
- It uses carrier proteins in the membrane.
Practice
Active transport moves particles:
Active transport is "uphill" (low → high), so it needs energy and carrier proteins.
How it differs
| Process | Direction | Energy? |
|---|---|---|
| diffusion | high → low | no |
| osmosis | high → low water potential | no |
| active transport | low → high (against the gradient) | yes |
- Example: root hairs take up mineral ions from the soil by active transport (even when there's already more inside).
Practice
Which process uses energy from respiration?
Only active transport uses energy; diffusion and osmosis are passive (down the gradient).
Practice
Root hairs take up mineral ions from the soil by:
Minerals are often more concentrated inside the root, so active transport (against the gradient) is needed.
You've got it
Key idea
- active transport moves particles against the gradient (low → high), needing energy from respiration and carrier proteins
- only active transport uses energy and goes against the gradient
- e.g. root hairs absorb mineral ions by active transport