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Osmosis in a Potato Chip.

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Introduction

Osmosis in a Potato Chip Aim: During this experiment I shall be investigating osmosis in a potato core. I shall also be investigating the effect the concentration of the solution has on the osmosis of a potato core. Possible Input Variables: - concentration of glucose - surface area of potato core - temperature (this however will only effect the rate of osmosis) - variety if potato, vegetable - whether the potato is cooked - what the solute of the solution is, possible change of solute My chosen input variable will be the concentration of the glucose. I have chosen this variable because it is practical and easy to regulate. It will give us clear results which will enable us to find dynamic equilibrium. Control Variables: - surface area of potato core - temperature - variety of potato, vegetable - whether the potato is cooked - what the solute of the solution is Possible Outcome Variable: - change in length of potato core - percentage change in length of potato core - volume of solution left - change in weight - percentage change in weight My chosen outcome variable will be the percentage change in the length of the potato core. I have chosen this because this outcome variable will give us a clear set of results which will enable us to draw a clear graph and we shall therefore be able to find dynamic equilibrium. ...read more.

Middle

Diagram of Experiment: Safety: - tie long hair back - wear lab coats - wear safety specs - be careful of finger when cutting the potato with the scalpel - if any glass is broken report it to the teacher immediately After studying the preliminary method I can see that it needs some changes and so I have provided a more detailed and accurate method. Apparatus: - 5 test tubes - A tile - Forceps - Scalpel - 5 syringes - A 25cm3 measuring cylinder - 5 different sucrose concentrations (0%, 5%, 10%, 15%, 20%) - A test tube rack - A millimetre ruler - 1 potato - A potato corer Method: 1. Firstly we have to measure out our concentrations. Our stock solution is 20% sucrose and so our maximum solution can be 20%. We shall make a maximum of 100cm3 of each solution. 2. To make the first concentration (0% sucrose) we shall use distilled water as there is no sucrose present in this solution. 3. For the rest of the solutions the table below will explain which amounts to use for which concentration. Sucrose concentration 0 5 10 15 20 Volume of 20% sucrose/cm3 0 25 50 75 100 Volume of water/cm3 100 75 50 25 0 Total volume/cm3 100 100 100 100 100 4. ...read more.

Conclusion

In my preliminary experiment the cells which were shorter in length were bendy and this supports my prediction. I predict that when the potato cores are placed in solutions with low sucrose concentrations they will get longer. I think this will happen because the solution inside the cell will be more concentrated than the solution outside the cell. Therefore water will pass into the potato cells and the net flow will travel down the concentration gradient by osmosis. This will cause the potato cells to become turgid which is when a cell has swollen to its full capacity, and there will be a net gain of water molecules. In my preliminary experiment the cells which were longer were stiff and this supports my prediction. Diagrams: These diagrams show what a concentrated and dilute solution look like. Diagrams of turgid and flaccid cells These diagrams show what the cells will look like when they are both turgid and flaccid. These can help explain the reason why, when the cells have been taking in water and are turgid the cores are firm. It also helps explain why, when the cells have been losing water and is flaccid, the cores are limp. If a massive amount of water is lost from the cells then the cells become plasmolysed which means that the cytoplasm starts to peel away from the cell wall. Reference: Biology For You ...read more.

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