Moving water in plants
Show on a big screenA tall tree has no heart. Yet water reaches its highest leaf. Water travels up inside narrow tubes called xylem. Water vapour is water as a gas.
- A plant: leaf, xylem tube, roots.
- Water vapour leaves through the leaf.
- This pulls water up the tube.
- The pull reaches down to the roots.
Loading lab…
Slide the stomata open. Watch the water lost.
The rule
A plant loses water vapour through tiny pores called stomata. This loss is transpiration. It pulls water up through the xylem.
The phloem is the other tube. It carries the food made in leaves. This is translocation.
| Tube | Carries | Direction |
|---|---|---|
| Xylem | Water and minerals | Up, from roots |
| Phloem | Food from the leaves | Up and down |
By day, transpiration pulls water up the xylem. At night, root pressure matters more. The phloem carries food both up and down.
Root pressure comes from roots taking in ions. Ions are tiny charged particles. Water follows and is pushed up. Moving food in the phloem needs energy from ATP. ATP carries energy to where the cell needs it.
Try the lab to finish this lesson.