About Lesson
Absorption of water by roots
The root hair cell sap is hypertonic to the solution in the soil; Water molecules move into the root hair cells by osmosis. The cell sap of the root hair cells become hypotonic to the neighbouring (cortical) cells; Hence, lose water to the neighbouring (cortical) cells by osmosis. This continues successively until water passes the cortex and endodermis reaching the xylem of the root.