Question

Correct the following statement by changing the underlined word. The cell sap of root hair is hypotonic.

Answer 1

In higher plants water is absorbed through root hairs from the soil. Root hair walls are permeable for water for water.

Complete Answer:
- Root hairs are slender thin walled extensions of root, epidermal cells which increase the surface area for absorption.
- The water is absorbed by the roots from the soil and moved to conducting tissue. It has to be transported to various parts of the plant.
- Root hair walls are permeable for water and it is hydrophilic.
- Root pressure is the positive pressure that develops in the root by active absorption of nutrients from the soil.
- A cell sap is found in the root hair. It has a high concentration of salt as compared to surrounding soil water. So water moves from outside to inside root hair. The absorbed water reaches vascular tissue and from here it is supplied to all parts of the plant. So concentration of solute in cell sap is high.
- In xylem sap a negative water pressure occurs. The reason for that when a cut is given to a shoot the water does not spill out. The rate of absorption of water is equal to transpiration rate.
- The cell sap has higher water concentration than the surrounding water which means that cell sap has less water potential and soil has high water potential.

The cell sap of root hair is hypertonic.

Note: Absorption of water is affected by the environmental conditions. These conditions are
- Available soil water
- Concentration of the soil solution
- Soil air
- Soil temperature