The Plant Root
- The roots, stem and leaves form a plant organ system for the transport of substances around the plant
- Plant roots are adapted to maximise absorption of water and mineral ions from the surrounding soil
- Many epidermal cells in the root have 'hair-like' extensions that project into the soil
- Roots contain millions of these 'hairs' to increase the surface area for absorption
The structure of a root specifically allows it to maximise absorption of water by osmosis and mineral ions by active transport
Root hair cells
- Root hair cells are adapted for the efficient uptake of water (by osmosis) and mineral ions (by active transport)
- Root hairs are single-celled extensions of epidermis cells in the root
- They are long and thin so they can penetrate between soil particles and absorb water and minerals from the soil
- Root hairs increase the surface area to volume ratio which increases the uptake of water and mineral ions
- The high proportion of dissolved minerals and sugars in the cytoplasm (of the root hair cell) gives it a low water potential
- As soil water has a higher water potential than the cytoplasm, water moves into the root hair cell by osmosis
- Mineral ions move into the root hair cells by active transport as the concentration of mineral ions in the soil is usually much lower than in the root hair cells
- They need to move into the cell against the concentration gradient which requires energy
A root hair cell
