Semipermeable Membranes and Bioaccumulation

Beginning biologists place a drop of food coloring into water of differing temperatures to observe the effect on the diffusion rate. They remove the shells from raw eggs and then experiment with osmosis over the remaining membranes. Finally, they use dialysis tubing to simulate the movement of toxins over selectively permeable membranes. A lab sheet for students follows the teacher's notes. The three activities progress well, revealing more of the intended concepts with each step.