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Unformatted text preview: The Effect of Glucose on Osmosis in Potato Cores ABSTRACT In this experiment, we investigated three possible explanations for what predicts osmosis. We investigated how the percent weight change of white potato cores changed as it depended on water concentration, osmolality, and grams of solute per liters of solvent. The experiment was conducted and results were obtained which led us to the conclusion that our hypothesis that osmolality is the best predictor of osmosis was supported by the data. Vant Hoffs Number of Particles Explanation is t rue. INTRODUCTION The purpose of this investigation is to observe the effect of NaCl, glucose, and sucrose solutions of different concentrations on potato tissue in order to approximate the water potential of potato tissue (Kosinski). Through the data obtained in the experiment, we could then determine whether the rate of osmotic water movement is determined most by the water concentration, the mass of solute per liter of solution, or the number of solute particles per liter of solution (Kosinski). Osmosis is the net movement of water across a selectively permeable membrane caused by a difference in the concentrations of solute on the two different sides of the membrane. A selectively permeable membrane is a membrane that allows unrestricted passage of water, but no passage of solute molecules or ions (Bowen). If the concentration of solute in the solution is greater than the concentration of solute in the cells, the cell is in a hypertonic solution (Steinberg). This means that more water leaves the cell than enters it, in order to reach equilibrium. If the concentration of solute in the solution is l ess than the concentration of solute in the cells, the cell is in a hypotonic solution (Steinberg). This means that more water enters the cell than leaves it, causing the cell to swell. Animal cells will usually burst if they are in a hypotonic solution, but animal cells thick and rigid cell wall is strong enough to keep the cell from bursting. Pressure, called turgor pressure, will build up on the cell wall and cause it to bend outward, but the cell will not break. Turgor pressure on the walls of plant cells is what keeps plants from drooping (Steinberg). Eventually, the cell will come to equilibrium in a hypotonic solution because the amount of water is leaving due to turgor pressure and the amount of water going into the cell due to osmosis are the same (Kosinski). Water potential is a concept that combines turgor pressure and osmosis (Kosinski). The equation that describes water potential is: = p + s , where is water potential, p is pressure potential, and s is osmotic potential (Kosinski)....
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