Potato Tuber Lab Essay

Introduction: Osmosis is a form of diffusion in which water diffuses through a selectively permeable membrane from a region of high concentration to a region of lower concentration. This form of diffusion takes place when the molecules in high concentration are too large to move through the membrane. Three factors that determine cell membrane permeability are shape, size, and polarity. For this experiment, it must be kept in mind that sucrose is not permeable to the cell membrane, for it is too large to pass through. The cell membrane functions to protect, separate, and regulate what goes in and out of a cell. It also allows cells to control their internal chemical environment and the availability of important materials. In a hypertonic solution, there is a greater concentration of solute inside a cell compared to another solution (water will flow from out of the potato cells and the mass will decrease). In a hypotonic solution, there is a lower concentration of solute compared to another solution (water will flow into the potato cells and the mass will increase). In this potato tuber lab experiment, the weight of each potato tuber after being sliced into thin disks and rinsed was taken and recorded. The potato disks were then individually placed in sucrose solutions for exactly an hour, each cup being swirled every ten minutes. At the end of the hour, each group of potato tuber slices was weighed a second time to determine if there was a change in mass due to the sucrose solution. The percent change in weight among the different potato tubings was determined in order to confirm or deny our hypotheses. My null hypothesis was that the potato would not be affected by the sucrose solution, the osmotic concentration would neither increase nor decrease, therefore there would be no change in mass seen. My alternate hypothesis was that the potato would be affected by the sucrose solution (final mass) by having a higher or a lower osmotic concentration than the initial mass, therefore there will be a change in mass seen. Results: The initial weight of the sliced potato tubers ranged from 4.4g to 5.4g. The final weight of the sliced and soaked potato tubers ranged from 3.6g to 5.7g. These results show that the 0.1 solution of sucrose was hypotonic, causing the sliced potato pieces to gain mass, as to where the remaining solutions of sucrose (.00, 0.2, 0.3, 0.4, 0.5) were hypertonic, causing the sliced potato pieces to lose mass. This shows that the potato tubers were affected by the sucrose solutions. This conclusion is represented in the graph given below. Discussion: The purpose of this experiment was to determine the osmotic concentration of sucrose within the potato tuber slices. Upon coming up with the final results of the experiment, the osmotic concentration of sucrose was calculated to be .06M. For this experiment, an isotonic solution will have a molarity of .06M, as the best fit line hits the x axis at .06M. In comparison, a hypotonic solution will have a concentration ranging from 0 M to .06M, and a hypertonic solution will have a concentration ranging from .06M or higher. This caused me to accept the alternate hypothesis and reject the null hypothesis; therefore, the potato was affected by the sucrose solution as we saw a change in mass of the potato tuber slices.