Water with dissolved mineral salts inside a cell is called Cell Sap or Sap. The apical region of root (Meristamatic region and root hair region) absorbs water and mineral salts from the soil. The process by which the cell sap raises from the absorption region to the leaf and other parts is called ascent of sap. This raising of sap takes place through Vessels and Tracheids of Xylem tissue.
The root hairs are spread in the spaces between soil particles. In the spaces, there is capillary water. The concentration of cell sap in the root hairs is more than the water and dissolved mineral salts in the soil. Thus water enters into the root hairs by osmosis. When water enters into the root hairs the concentration of its sap become less than the concentration of the sap of the adjacent cell. As a result water from root hair moves to the adjacent cell by osmosis.