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What is the concentration of the cell sap in the vacuoles of potato cells?

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Introduction

Biology Investigation PROBLEM: What is the concentration of the cell sap in the vacuoles of potato cells? BACKGROUIND INFORMATION: * The structure of a plant cell - 1. The nucleus contains chromosomes and genes (which are the instructions, which control the activity of the cell). 2. The mitochondria are the structures in a cell where the reactions of respiration take place. 3. The chloroplasts are the places where photosynthesis takes place. 4. The cell membrane is there to keep each cell separate from the rest and it also controls the passage of substances in and out of the cell. 5. The cell wall is a non-living structure that supports plant cells. 6. The cytoplasm is a jelly-like fluid in which substances move and many chemical reactions take place here. 7. The vacuole is filled with a watery liquid in which minerals are stored. * Water is an inorganic substance found in cells. Other substances that are found in cells are carbohydrates, fats and oils (lipids), proteins, nucleic acids (all of which are organic), salts and water (both of which are inorganic). * Osmosis is the movement of water molecules from a high to low concentration of water molecules through a partially permeable membrane. An example of osmosis is plants taking in water. ...read more.

Middle

These results will then be plotted on a graph and the line of best fir drawn. This will enable me to determine the concentration of cell sap that there is in the vacuole of potato cells. This will be where the line crosses the x-axis as at that point there is no change in the mass of the potato cylinders indicating that the concentration inside and outside the potato is the same and no water has transferred in either direction. PREDICTION: I predict that the concentration of cell sap in the vacuoles of potato cells will be below 0.5 moles. I think that this will be the case because potatoes are not very sweet and most of the glucose is turned to starch and stored. For a more precise prediction, I predict that the concentration of cell sap in the vacuoles of plant cells will be 0.4 moles. I believe this to be the case because potatoes are storage organs; this means that most of the sugars in the potatoes are turned to starch i.e. glucose is converted to sucrose and then to starch. Potatoes are also polysaccharide i.e. they are insoluble so as not to cause osmotic problems to the cells. I also know that potatoes are not very sweet which would indicate that they do not have much glucose or sucrose in them. ...read more.

Conclusion

to work out the exact answer. This would also provide additional evidence for my conclusion that the concentration of cell sap is 0.2 moles. As the experiment was performed in a school laboratory where the temperature is not always kept constant, my results may not be entirely accurate. To obtain better results, the potato cylinders and the solutions would have to be kept at a constant temperature throughout the experiment. To extend the investigation further I could see whether it is necessary for the membranes to be living when the experiment is performed. To do this I would have to destroy the living membranes by boiling the potatoes for one or two minutes. I would then repeat the same experiment again to see if the results are different. The potatoes would not be boiled for any longer than two minutes because they would become soft making the experiment harder to do and also because to kill the membranes it would only take this amount of time. I would expect the results of this additional experiment to be very similar to those of the original experiment as I have observed the same effect with visking tubing, which is not living. The experiment could also be extended to use different size pieces of potato and different volumes of solution, although I would not expect this to alter the conclusion. ...read more.

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