OSMOSIS LAB

1. OSMOSIS LAB Whitney Dougherty, Divya Arcot, Kelly Christensen, Molly Horton Period 4

2. What is Osmosis? • Osmosis is the diffusion of water from areas of higher concentration to areas of lower concentration. • (From hypotonic solutions which contain less of the solute to hypertonic solutions which contain less of solvent) • This takes place in order to maintain homeostasis within cells.

3. Purpose • To determine how varying the type of food and amount of salt concentration affects osmotic regulation.

4. Procedure • Cut potato & apple (approximately 1cm) • Weigh samples in grams • Place in variable salt solutions* • Sit for 30 minutes • Removes samples, dab dry, & re-weigh • Record data & analyze results *see next page Salt

5. Procedure (continued) How to make a salt solution: 1. Measure 50 mL of distilled water 2. Measure the amount (in grams) of salt, which will be the same number as the percentage of salt in the solution (ex. 5 grams for a 5% salt solution) 3. Pour the salt into 50 mL of the solvent 4. Stir solution until the salt is visibly dissolved 5. Add 50 mL of the solution, so that you have a total of 100 mL of the solution.

6. Procedure (continued) Controls Variables • Size of samples • Amount of solvent (H2O) • Time • Type of food • Salt Concentration VS. Distilled H20 1% Salt 5% Salt 10% Salt

7. Hypothesis • Because apples and potatoes are composed of different materials, their chemical properties differ. These characteristics will in turn cause variations in their rates of osmosis. The rates of osmosis of the apple and potato samples will also vary in different manners when the samples are placed in salt solutions.

8. Prediction • We think the potato will have a higher rate of osmosis because they are more dense due to their starch concentration. In comparison, apples are less dense and have a higher concentration of water.

9. Data

10. Percent Change in Mass EQUATION MassInitial – MassFinal _______________________________X 100 MassInitial

11. Percent Change in Mass(Graphed)

12. Conclusion The purpose and corresponding results: • The purpose of this lab was to observe the effects of food types on osmotic rates in various salt solutions. • Our data showed that our prediction was correct. It showed that the potato had a higher rate of osmosis than the apple.

13. Conclusion What could have gone wrong? • Although our prediction was correct, the results of our data were inconclusive, as they did not exactly follow theory. We believe this was due to: • Potential contamination of the distilled water as the data collected from the other solutions followed the osmotic theory. • Denatured aquaporin pumps which facilitate the flow of water into the cells of the food samples. • The fact that samples were taken from foods which had been sitting out for a while.

14. Conclusion What We Learned: • We learned how the cell membrane of different foods respond in a similar fashion to variable salt concentrations of a solvent. • Since our results were inconclusive, the best method of action is to re-do the experiment. In this way, we would be able to test whether the distilled water was actually distilled and verify the consistency of the rest of our results which followed osmotic theory.