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Finding the isotonic point for potato tissue

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Noémie Pauwels BIOLOGY COURSE WORK Finding the isotonic point for potato tissue 1. Raw results table Concentration of sucrose solution (M) Mass of potato sticks (g ±0.01g) Before soaking in sucrose solution After soaking in sucrose solution for 30 min. 0.0 2.90 3.05 2.90 3.04 2.86 3.05 2.88 3.01 2.80 2.98 2.87 3.01 0.2 2.96 3.01 2.97 3.03 2.90 3.04 2.91 2.98 2.80 2.86 2.87 2.96 0.4 2.90 2.84 2.87 2.83 2.76 2.73 2.84 2.77 2.83 2.79 2.90 2.81 0.6 2.97 2.81 2.98 2.74 2.99 2.78 2.91 2.80 2.97 2.79 3.00 2.77 0.8 2.81 2.61 2.88 2.63 2.87 2.61 2.90 2.62 2.91 2.64 2.92 2.68 1.0 2.88 2.69 2.88 2.62 2.92 2.64 2.89 2.61 2.90 2.61 2.88 2.62 1. Processed results table Concentration of sucrose solution (M) Mass of potato sticks (g ±0.01g) Before soaking in sucrose solution Before soaking in sucrose solution Difference Percentage change in mass of potato sticks (%) Mean percentage change in mass of potato sticks (%) Standard deviation of percentage change in mass of potato sticks (%) 0.0 2.90 3.05 + 0.15 2.90 3.04 + 0.14 2.86 3.05 + 0.19 2.88 3.01 + 0.13 2.80 2.98 + 0.18 2.87 3.01 + 0.14 + 5.17 + 4.83 + 6.64 + 4.51 + 6.43 + 4.88 + 5.41 0.82 0.2 2.96 ...read more.


This means that the rate of osmosis would be faster and that the potato sticks would increase or decrease in mass faster. TYPE OF ERROR: This is a procedural and significantly major error because the temperature is not even measured. IMPROVEMENT: Heat the sucrose solution for 20 minutes in a boiling tube in a water bath set to 25 °C and check the temperature of the water with a thermometer before adding the potato pieces. 1. PROBLEM: Difference of potato sticks EXPLANATION: The cells of the potato sticks have different concentrations of solutes because more than one potato was needed to obtain enough samples of potato. Cells with a greater concentration of solutes would absorb more water and gain more mass when soaked in 0.0 M sucrose solution. The potato sticks are not from the same potato. This means that the cells have a different solute concentration, a different concentration gradient and so the rate of reaction would be different. TYPE OF ERROR: This is a procedural and significantly major error. This factor limits the reliability of the method. IMPROVEMENT: Check the solute concentration of the potato cells and adapt the concentration of the sucrose solution to reach a same concentration gradient. ...read more.


From the graph, we can conclude that the more hypertonic the potato sticks are to the sucrose solution, the more the potato sticks will increase in mass. On the other side, when the potato sticks are more hypotonic to the sucrose solution, the mass of the potato sticks will decrease more. 1. Glossary - concentration gradient : a gradual change in the concentration of solutes in a solution - cytoplasm : living part of the cell, bound by the plasma membrane, excluding the nucleus. - dilute solution : a solution that contains a small concentration of solute.. - hypertonic solution : a more concentrated solution (one with a less negative water potential) than the cell solution. - hypotonic solution : a less concentrated solution (one with a more negative water potential) than the cell solution. - isotonic : being of the same osmotic concentration and therefore of the same water potential. - kinetic energy : energy in movement. - micrometer : A device for measuring very small distances - osmosis : passive movement of free water particles from a more dilute solution to a more concentrated solution across a partially permeable membrane along a concentration gradient. - plasmolysis : withdrawal of water from a plant cell by osmosis. - solute : a substance dissolved in another substance. - turgid : having high internal pressure ...read more.

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