Name __________________________________________________________________________ Period ___________ Date___________________
Selectively Permeable Membranes and Osmosis Diffusion results from the random motion of molecules. Diffusion moves substances from regions of higher
concentration to regions of lower concentration. Diffusion of water across a selectively permeable
membrane is called osmosis; osmosis results in net movement of water from a solution with a high
concentration of free water molecules (low concentration of solutes) to a solution with a low concentration of
free water molecules (high concentration of solutes).
Materials: 2 beakers Potato slices Salt solution water
Procedure: 1. Describe the potato slices when you first received them from your teacher. 2. Place one slice of potato into the salt water. Place one slice of potato into the plain water. 3. In the ‘Prediction’ colums of Table 1, predict what will happen to each of the potato slices after the alotted time has passed. Use the terms flaccid (flimsy), turgid (firm) or no change for descriptions. 4. At the end of the period and again after one day, compare the two pieces of potato, fill in the data table. Again, use the terms flaccid (flimsy), turgid (firm) or no change for descriptions. 5. Answer the questions on your lab sheet. Table 1. Distilled Water Salt Solution Prediction End of After Period 1 Day Actual End of Period After 1 Day Name __________________________________________________________________________ Period ___________ Date___________________
Selectively Permeable Membranes and Osmosis Lab Sheet Answer these questions after the allotted soaking time has passed. Analysis 1. Circle the hypertonic solution as compared to the potato. salt water distilled water 2. Circle the hypotonic solution as compared to the potato. salt water distilled water 3. Use the beakers below to draw each of the lab set ups. Add the potato slice then label each beaker as containing a hypertonic or hypotonic sloution. Use arrows to show the movement of water molecules. salt water distilled water 4. Explain WHY the results occurred as they did in the salt water. 5. Explain WHY the results occurred as they did in the distilled water. 8. What part of the potato is selectively permeable? 9. Predict what would happen if the potato were placed in an isotonic solution. 6. Define osmosis. 7. What is a selectively permeable membrane?