Key learning points

1. Cells in all parts of a multicellular plant need water and nutrients, such as mineral ions, to stay alive.
2. Xylem and phloem transport substances around the plant and minimise the distance they have to diffuse to reach cells.
3. Root hair cells are an example of an exchange surface in plants.
4. The root hair cell membrane is adapted to maximise the surface area for osmosis of water and active transport of ions.

Keywords

• Diffusion - the net movement of particles from an area of higher concentration to an area of lower concentration

• Active transport - the net movement of particles against a concentration gradient using energy

• Osmosis - the net movement of water molecules through a selectively-permeable membrane from high to low concentration of water molecules

• Exchange surface - a specialised surface which enables the efficient exchange of substances

• Surface area - the total area of the surface of an object

Common misconception