The Root Hair Cell

FUNCTIONS

• Responsible for the absorption of water from the water film surrounding the soil particles by osmosis.
• Allow simple diffusion of dissolved mineral salts in the soil solution to pass into the root hair. This is only possible if a concentration gradient is present (ie if such minerals in the salt in the soil water are in greater concentration than in the root hair cell)
• The root hair cells absorb minerals that are present in low concentration in the soil by active transport.

ADAPTATION TO FUNCTION

• The root hair cell is able to form very close contact with the water film surrounding many soil particles. This allows rapid and efficient absorption of water from the soil.
• The root hair cell is long and narrow. This increases the surface area to volume ratio of the cell for rapid absorption of water and mineral salts from the soil.
• The cytoplasm and cell sap of root hair cells contains a high concentration of sugars, amino acids and mineral salts. Water in the soil therefore diffuses into the root hairs, down the water potential gradient, through the partially permeable cell membrane into the vacuole by osmosis.