Concept 2 Review

A Closer Look: Plant and Animal Cells in Hypotonic Environments

Click on the "Play" buttons to see the effects of hypertonic environments on plant and animal cells.

Turgor in Plants

Plant cells are surrounded by rigid cell walls. When plant cells are exposed to hypotonic environments, water rushes into the cell, and the cell swells, but is kept from breaking by the rigid wall layer. The pressure of the cell pushing against the wall is called turgor pressure, and is the desired state for most plant tissues. For instance, placing a wilted celery stalk or lettuce leaf in a hypotonic environment of pure water, will often revive the leaf by inducing turgor in the plant cells.

Lysis in Animals

Animal cells lack rigid cell walls. When they are exposed to hypotonic environments, water rushes into the cell, and the cell swells. Eventually, if water is not removed from the cell, the pressure will exceed the tensile strength of the cell, and it will burst open, or lyse. Many single-celled protists living in freshwater environments have contractile vacuoles that pump water back out of the cell in order to maintain osmotic equilibrium and avoid lysis.