1. Modeling the Digestive System Lab Set-up 1: 10 ml of 1% starch solution + 10 ml water inside dialysis tubing & tie off Set-up 2: 10 ml of 1% starch 1% amylase solution + 10 ml of water inside dialysis tubing & tie off Set-up 3: 10 ml of soda inside dialysis tubing & tie off Mass each dialysis tubing prior to putting in cups of water. TO BOTH 1 & 2 add 3 drops of iodine to the water in the cup RECORD THE OBSERVATIONS OF EACH SET-UP

2. Predictions Predict: 1)What will the color of the water in each cup be tomorrow? 2)What will the color of the contents inside the dialysis tubing of each cup be tomorrow? 3)What will happen to the starch in the cup 2 compared to cup 1? Why? Will the iodine test be any different? 4)Where will the most sugar be concentrated in the 3 rd set-up – in the tube or in the water? 5)How will the mass of each bag change?

3. Conclusions Record the observations of each set-up Explain the conclusions you can draw about the permeability of dialysis tubing from your results and the mass of the dialysis tubes. Compare and contrast the dialysis tubing with the plasma membranes that carry out absorption in the villus epithelium cells in the wall of the small intestine. Use the results to predict the direction of the movement of water by osmosis in each cup.