Question

Water will be absorbed by the root hair when:

• A. concentration of solutes in the sap is high
• B. plant is rapidly respiring
• C. they are separated from soil by permeable membrane
• D. concentration of salts in the soil is high

Answer 1

The correct option is A

concentration of solutes in the sap is high

Correct answer is option A.

Explanation for correct option:

1. The absorption of water mainly takes place in the terminal ends of the roots but occurs maximum in the area of root hair.
2. Root hair contains cell sap which has a higher concentration of salts as compared to the soil water.
3. Hence the root hair cells absorb water from the soil by the process of endosmosis.

Explanation for incorrect option:

Option B:

Water absorption in plants takes place by root hairs by the process of endosmosis and respiration creates no effect on it.

Option C:

1. The process by which water enters the root hair cell is called as osmosis.
2. Due to the semi-permeability and low potential of water in the root than in the surrounding soil, water enters into root hair through osmosis.

Option D:

Water is absorbed by roots when concentration of solute in cell sap is higher because then water potential in the root will be lower than water potential in surrounding soil solution.

Final answer: Water will be absorbed by the root hair when concentration of solutes in the sap is high.