Figure 7.6 Cell responses to solutions of differing osmotic content.
Cells with cell wall
Isotonic solution: Water concentration is equal inside and outside the cell, thus rates of diffusion and equal in both directions.
Hypotonic solution: Net diffusion of water is into the cell; this swells the protoplast and pushes it tightly against the wall. Wall usually prevents cell from bursting.
Hypertonic solution: Water diffuses out of the cell and shrinks the cell membrane away from the cell wall; process is known as plasmolysis
Cell lacking walls
Direction of net water movement.
- Rates of diffusion are equal in both directions.
- Diffusion of water into the cell causes it to swell, and may burst, it if no mechanism exists to remove the water.
- Water duffusing out of the cell causes it to shrink and become distorted.