Students Investigate Osmosis and Diffusion

In the AP Biology course the students carry out two proscribed protocols/procedures related to osmosis and diffusion. In one they use agar cubes to represent various sized cells. They then measure how far into the cells the materials diffused over a fixed period of time. They then calculate the rate of diffusion. They also calculate surface area to volume ratios. In the second protocol, they use dialysis tubing to represent cell membranes. Varying molarity solutions are place in the "cells" the their masses before immersion in water and after immersion are recorded. Finally, the students are given the task of devising their own investigation based on the two required protocols. They will be examining the effects of molecule size, molecule concentration, and other variables on the rate of diffusion/osmosis.

Lab 4 Diffusion and Osmosis by Charles Ippolito