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An investigation to find out the water potential of potato cells

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An investigation to find out the water potential of potato cells using sucrose solution Aim The aim of this experiment is to investigate the movement of water into and out of cells by osmosis. The cells chosen for study will be taken from potatoes as they provide a ready supply of uniform material. Hypothesis My hypothesis is that as you increase the concentrations of the sucrose solutions there will be a net loss in mass of the potato cores, due to the water molecules moving out of the potato cells by osmosis. Background knowledge Water potential is a measure of the ability of water molecules to move from one region to another.' The more water molecules there are per volume of the cell the more likely that by random movement they will collide with the cell's plasma membrane, and travel out of it. Pure water has a water potential of 0. As all solutions have less water molecules per volume than pure water they have lower water potential, therefore all solutions have negative water potentials. The movement of water molecules is not totally random. ...read more.


Suitable background to observe variations in the tissue. Tweezers Enables potato to be held securely without skin contact, increasing accuracy of results. Tissue paper Used to blot the sides of the potato chips meaning the mass is not affected by any remaining solution on the surface of the potato. Each chip is blotted once, making the effect on mass uniform across all chips Electronic scales Measures the mass of potato chips, in grams, to two decimal places. To ensure the results are reliable use the same balance throughout the experiment Safety Apparatus Safety evaluation Boiling tubes Handle carefully to avoid breakage. Dispose of in sharp bin Potato chipper Minimal risk if used correctly Scalpel Sharp, avoid contact with blade Distilled water Minimal risk Sucrose solution Minimal -use fresh to avoid microbial contamination Tissue paper Minimal risk Electronic scales Avoid contact with liquids Potato tubers Minimal risk Beakers Handle carefully to avoid breakage. Dispose of in sharp bin Tube rack Minimal risk Tweezers Minimal risk White tile Minimal risk Measurements In my experiment, 2 sets of results are going to be taken. However, in my investigation, I am going to use the class results, as it will be more accurate. ...read more.


from 0-to1 mole, this would enable me to get more accurate results, and The main variable with the experiment was the drying of the chips, as some may not have been dried as much as the others may, if they were not dry, this could effect the concentration of the sugar. In addition, different areas of the potato may have different concentrations of cells, which can affect the experiment, although it is a minor point it could have a great impact also not all potatoes in the test are exactly in the same size as there will be measuring errors in both instrument and human. Even if the potatoes are in the same size, may not contain same no. of cells which will affect the rate of osmosis. When you cut the potato, you cannot avoid to "destroy" some of the cells. It also causes leakage of cell contents to the outside which causes shrinkage of the cells. Systematic errors like the measurement error when making the solutions can also cause errors. These are all minor points because they cannot be improved in a more accurate way except having better measuring instruments would help. ?? ?? ?? ?? .Page 1 of 9 Y.12B Janice Lau ...read more.

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