Water Potential in Plant Cells

Edexcel AS-level BiologyCell Transport MechanismsLesson 11 of 18

Plant cells behave differently from animal cells in osmosis because of their structure:
• a strong, fully permeable cellulose cell wall, which resists expansion and stops the cell bursting;
• a cell surface membrane, which is partially permeable;
• a large, permanent central vacuole that holds most of the cell's water;
• the vacuole is surrounded by its own membrane, the tonoplast, and contains cell sap, a solution of sugars, ions and other solutes.

The solutes in the cell sap and cytoplasm give the cell a negative water potential. As water enters, the cell contents push outwards against the wall, and the wall pushes back. This pressure raises the cell's water potential. So the water potential of a plant cell depends on both its solute concentration and the pressure from the wall (these two parts are covered separately in the next lessons).

More in Cell Transport Mechanisms

• Osmosis
• Modelling Osmosis
• Osmotic Concentrations
• Osmosis in Animal Cells
• Osmosis in Plant Cells
• Turgor Pressure (P)
• Osmotic Potential (π)
• Water Potential, Turgor Pressure and Osmotic Potential

All 18 lessons in Cell Transport Mechanisms · All Edexcel AS-level Biology topics