When placed in fresh water (a hypotonic solution), both plant and animal cells take in water by osmosis because the water potential outside the cell is higher than inside. However, they behave differently due to their structural differences: Animal cells lack a cell wall. As water enters, the cell swells and the cell membrane cannot withstand the increasing internal pressure, causing the cell to burst (lyse*). Plant cells possess a rigid cell wall outside their cell membrane. As water enters, the cell swells and the cell membrane pushes against the cell wall. The strong cell wall prevents the cell from bursting, making the cell turgid*. This turgor pressure provides support to the plant.