An investiagtion to establish the isotonic point of potato cell sap

Essay by ricardo905High School, 11th grade February 2004

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I have been asked to investigate the effects of osmosis on potato cell sap. I will test potato cylinders in different strengths of sucrose solution and record any results in a table. I will then analyse my findings and work out the isotonic point of the potato cell sap.


I have looked at my scientific knowledge from the background theory I carried out and I will base my prediction upon this information. In this experiment, I expect the different concentrations to show fairly noticeable effects on the lengths and masses of the potatoes, with the water diffusing into the potatoes at a high rate in the sucrose solution and therefore making their size bigger than at the start. As the distilled water solutions become stronger, I expect the rate of osmosis to increase (and, as a result, make the potatoes themselves comparatively bigger at the end). Also, the potatoes will be quite turgid at the start of the experiment, there will be already some water inside, and because of this I expect, in the stronger solutions, for there to be a decrease in the mass and length of the potato, due to a reversal in the effect of osmosis.


· 6 test tubes

· White tile

· 1 molar sugar solution

· Electronic balance

· Stopwatch

· Measuring cylinders

· Ruler

· 12 pieces of potato (0.8g each)

· 2 beakers

· Distilled water


We cut 12 pieces of potato using the cork borer and knife, and then we weighed each piece to 0.8g using electronic scales. The lengths of each potato cylinder varied so we measured them using a ruler and wrote the different lengths down. We placed the potato cylinders on a paper towel in order to dry any excess residue from them, and keep...