1. Diffusion across a Selectively Permeable Membrane

2. Start… • Predict which molecules will cross the membrane (and why). • Use those predictions to complete the “Final State” diagram at the bottom of the first page. • Describe expected colors of each liquid after the experiment (top of back of 1st page) • Determine a method to test whether water is moving in or out of the tube.

3. Procedure • Following directions, make tube. • It will have a mixture of starch, glucose and water in it • Beaker will have iodine and water Starch & Glucose solution

4. Record… • Record observations at the beginning of the experiment. • Color of liquid in tube • Color of liquid in beaker • Record beginning value you are measuring to evaluate water movement. • Wait 10-20 minutes.

5. Observe final state of starch/glucose tube. • Test iodine/water in beaker for glucose (using glucose test strip). Yellow tip turns brown or green in the presence of glucose. • Record your final state results in the table.