Transport of Water & Mineral Ions in Plants (OCR GCSE Biology A (Gateway))

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