Question

Root hair absorb water from soil through
A. Diffusion
B. Imbibition
C. Osmosis
D. Osmosis

Answer 1

Hint: Root hairs of the roots are in direct contact with the soil particles. As water is absorbed, the soil present near the root surface becomes depleted of the water. This results in a reduced pressure potential in the water present near the root surface. On the other hand, the adjacent soil regions have a higher pressure potential.

Complete step by step answer: Cells communicate with other cells and their surroundings. Movement of substances in and out of the cells occurs through two processes: active transport and passive transport.
Active transport moves the substances at the expense of energy. Passive transport moves the substances without any expenditure of energy.
When substances move from the region of their higher concentration to that of their lower concentration, it is called diffusion. Osmosis occurs when water from the area of its higher concentration to that of its lower concentration. Here, the two regions should be separated by a semipermeable membrane.
Both diffusion and osmosis are passive modes of transport. Absorption of water by a solid surface is called imbibition. Absorption of water by seed during germination represents imbibition.
Plants absorb water and minerals from the soil with help of roots. Roots have thin and slender extensions of the epidermal cells called root hairs which increase the surface area for absorption.
Absorption of mineral ions from the soil by roots occurs through active transport. The movement of mineral ions from the soil into the xylem of the root hairs establishes a pressure gradient. The pressure gradient drives the osmotic transport of water from the soil into the xylem tissues of the roots.
So, the correct answer is option C. Osmosis.

Note: Water always moves from the region of higher water potential to that of the lower water potential. Pressure potential is a component of water potential. Positive pressure potential is called turgor pressure. It increases the water potential while the negative pressure potential is called tension.