Osmosis is the movement of water across a membrane in an effort to dilute a molecule that is highly concentrated on the other side. Water moves across a membrane toward an area where another molecule is highly concentrated in order to dilute that molecule. Osmosis is a form of passive transport.

Cells can be found in a hypotonic solution, a hypertonic solution, or an isotonic solution. If the solution around a cell is hypotonic (meaning there is less solute outside the cell than inside the cell), water will enter the cell, and the cell will swell. If the solution around the cell is hypertonic (meaning there is more solute outside the cell), water will leave the cell, and the cell will shrink. With a cell in an isotonic solution, the concentration of solutes is the same inside and outside the cell. In the activity below, match the term on the right to its description on the left.

In this lab, you will investigate the effect of various concentrations of salt water on organic material. You will measure the volume of each sample of organic material before and after placing them in water with varying salt concentrations.