Water appears to cross the differentially permeable membrane of potato cells by a process called osmosis. During seven-lab experiments our class found that when we soak a potato and a prune in ODL water it will gain weight but if we soak a potato in Nasal solution it will lose weight but a prune soaked in Nasal solution will gain weight just as it did in the ODL water. Introduction: All cells contain membranes, which are selectively permeable, allowing things to pass in and out of the cell.
The process which molecules of a substance move from areas of high concentration to low concentration is called diffusion. Osmosis is the process in which water crosses membranes from regions of high concentration to low concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis move both down and across a concentration gradient. Osmosis and diffusion are both types of passive transport that do not require help.
I hypothesize that the potato and prune in the Nasal solution will lose weight, whereas the potato and prune in the ODL water will gain weight. Method & Materials: In the osmosis lab we started by taking two potato slices, approximately the same size and dipped them in to water and weighed them each individually n an electronic balance and recorded the weight. Then we placed one piece in ODL water and the other piece in saturated Nasal for about 20 minutes.
We then blotted each dry and reweighed them and recorded the new weights. We repeated the same procedure with 2 prunes. We then determined the change in weight for each of the four groups and recorded the results. Results: Based on the observations of all seven-lab groups in our class, the potatoes increased in weight in ODL water and lost weight in the Nasal solution. As for the prunes both gained weight regardless of which solution it was in.