Biology – 3.1 Diffusion | e-Consult

Diffusion of solutes, particularly water, is vital for the movement of water across the cell walls of plant cells. This movement is primarily driven by the process of osmosis. Osmosis is the diffusion of water molecules across a semi-permeable membrane from a region of high water concentration (low solute concentration) to a region of low water concentration (high solute concentration).

The cell membrane acts as the semi-permeable membrane. It allows water molecules to pass through but restricts the passage of larger solute molecules like sugars and salts. In plant cells, the concentration of solutes inside the cell is typically higher than the concentration of solutes in the surrounding soil water. This creates a water potential gradient, with the soil water having a higher water potential.

As a result, water moves by osmosis from the soil water into the plant cell, helping to maintain turgor pressure. Turgor pressure is the pressure exerted by the cell contents against the cell wall. High turgor pressure is essential for plant rigidity and support. When the water potential inside the cell is lower than the water potential outside, water will move out of the cell by osmosis, causing the cell to become flaccid. Therefore, diffusion of solutes and the resulting osmosis are critical for maintaining water balance and structural integrity in plant cells.