Question

How do plants absorb water? Explain.

Answer 1

There are millions of root hairs on the tip of the root, which absorb water and minerals by diffusion. Diffusion takes place across cell membranes. Root hairs are a thin-walled, slender, extension of Epidermal cell, that increases the surface area of absorption. Active transport utilizes energy to pump molecules against a concentration gradient. Active transport is carried out by membrane-bound proteins. These proteins use energy to carry substances across the cell membrane.

The cell wall of root hair is permeable and allows the water and minerals to enter. The cell membrane is semi-permeable. So it allows the movement of water molecules from the region of higher concentration to the region of lower concentration. Once the water enters the root hairs, the concentration of water molecules in the root hair cells becomes more than that of the Cortex. So the water from the root hair moves to the cortical cells by osmosis and then reaches the xylem.

Due to transpiration, the water is lost from the leaves, and pressure is created at the top to pull more water from the xylem to the mesophyll cells, by the process of Transpiration pull. This extends up to the roots causing the roots to absorb more water from the soil to ensure the continuous flow of water from the roots to the leaves.