Osmosis in plant cells. Illustration of the changes in a plant cell in solutions of differing osmotic potential. Osmosis (the flow of water across a semi-permeable membrane, such as a cell membrane) occurs when there is a difference in relative solute-water concentrations. At left, in a hyperosmotic solution, water flows out of the cell, causing the cell body to shrink from the cell wall. At centre, in an isomotic solution, the cell is in a normal, flaccid state. At right, in a hyposmotic solution, water flows into the cell and it swells and becomes turgid. For osmosis in red blood cells, see image C023/8783. For this artwork without labels, see image C023/8786.