Question

Water absorption by root hairs occurs until

• A. Concentration of water in the cell sap is higher
• B. salt concentration in soil is higher.
• C. they are separated from soil by a selectively permeable membrane
• D. water potential is lower

Answer 1

The correct option is A Concentration of water in the cell sap is higher

• The root system is usually extensive and has root hairs which help increase the surface area for water absorption.
• Water enters the root hair cells and then moves from cell to cell until it reaches the root cortex it goes on to the xylem vessels to be transported to the leaves.
• Root hairs contain cell sap of a higher concentration than that of the surrounding soil water. That means there is less water potential inside the cell and high water potential in the soil. This difference sets off osmosis and outside water diffuses into the root hair.
• Hence, Water absorption by root hairs occurs until the Concentration of water in the cell sap is higher.
• So, the correct answer is 'Concentration of water in the cell sap is higher'.