Page 3 - Lesson Notes

Effect on Plant Cells
 A hypertonic solution causes water to move out of the cell and the cell

membrane tears away from the cell wall in a process called plasmolysis.
 An isotonic solution does not result in any net movement of water in / out of

the cell; however, a plant cell may become flaccid (soft, drooping or inelastic).

 A hypotonic solution causes water to move into the cell. The tough plant cell
wall limits the cells volume preventing it from bursting. Eventually no more

water can move into the cell, but instead the internal pressure of the cell
increases. The cell membrane starts to push against the cell wall. This is

known as turgor pressure and it causes the plant cells to become turgid

(swollen and firm). Plants rely on turgor pressure to maintain their rigidity. This
is why placing flower stems in a hypotonic solution helps to prevent them from

wilting.

TYPES OF OSMOSIS

 ENDOSMOSIS- is the movement of water into the cell when the cells are

placed in a hypotonic solution.

 EXOSMOSIS- is the movement of water out of the cell when the cells are

placed in a hypertonic solution.