Question

Explain how do plants get water from soil through their root hairs.

Answer 1

Osmotic pressure is responsible for the movement of water from the root hairs to the cortical cells and then finally to the xylem vessels. It is the force required to resist the movement of water through a semi-permeable membrane down the concentration gradient. There are water molecules present in the spaces between the soil particles. This water is available for the plants. The first interaction of water and the root hair cells is due to imbibition of water. This is the process of adsorption of water. The water then enters the cells of the root hair by osmosis. The movement of water is due to the difference in the osmotic pressure. The osmotic pressure of water in roots is high and so the water enters the root hair cells. The water is transported to the other cells in the root region by osmosis. The movements of water is through the root hairs to the cortical cells and then to the layer of endodermis is through the process of osmosis down the concentration gradient. The water enters the cortex mostly by apoplast pathway and then crosses endodermis through symplast to reach xylem vessels.