Question

Water will be absorbed by root hairs when the external medium is

• A. Hypotonic
• B. Hypertonic
• C. Isotonic
• D. Viscous

Answer 1

The correct option is A Hypotonic

Water will be absorbed by root hairs when the external medium is hypotonic. This kind of absorption takes place passively. The concentration of water in the soil is high while the concentration of water inside the root hair is low. So, the water can easily move from the region of higher concentration to the low concentration without expenditure of energy by facilitated diffusion through the aquaporins. Water is absorbed by the root hair from the soil. It passes the epidermis, cortex, endodermis, casparian strip and pericycle and xylem. After reaching the xylem it is pulled up by the transpirational pull.

So, the correct answer is option A.