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Plan and carry out an experiment to determine the concentration of potato cell cytoplasm

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Introduction

Plan and carry out an experiment to determine the concentration of potato cell cytoplasm Brief Definition of Osmosis: "Diffusion of fluid through a semi permeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane." Diagram: Plant cells have a strong cell wall surrounding them, when they take up water by osmosis they begin to swell up but the cell wall prevents them from bursting. Plant cells become what is called "Turgid" when they are put in dilute solutions, the characteristics of a turgid plant cell are it being swollen and hard, the pressure inside the cell then increases and eventually the pressure because too much and no more water can be absorbed by the cell. This is what makes the stems and leaves of the plant stand up and face the sunlight. When plant cells are placed in concentrated sugar solutions they lose water because of osmosis, basically the exact opposite happens when the plant cell is turgid and the cell becomes "Flaccid" and the cells shrinks and loses shape. When a plant cell becomes plasmolsysed this is usually because it has not got enough water. The cell contents peel away from the cell wall and under a microscope (seen below) the cell walls become visible. <Plasmolysed Cells < Flaccid Cells <Turgid Cells Definitions Hypertonic: Having the higher osmotic pressure of two solutions. Hypotonic: Having the lower osmotic pressure of two fluids. Isotonic point: Situation where a cell can neither swell nor shrink, or, the equal tension point Variables A Dependant Variable- The variable which is measured, in this case the mass of the initial and final mass of the potato chunks. An Independent Variable- This is the variable that is changed. In this case this is the concentration of the sucrose solution. ...read more.

Middle

(0.8M) 13. In the third tube we will add 10ml of sucrose solution. (0.8M) 14. We will take a cork borer and push it through a potato twelve times to make twelve potato chunks. 15. We will cut the ends off all the potato cylinders and made them all the same size using a ruler and measuring 2cm each time. 16. We will then weigh each individual potato chunk and record the mass. 17. We will then put 1 potato chunk in each specimen tube. 18. We will then leave them for 2 days. 19. We will then take each potato chunk out with tweezers and a sieve and dab then on paper to remove excess liquid. 20. We will then weigh each potato chunk again and record the results. Using a cork borer Results Before Concentration of sucrose solution (M) Specimen A (g) Specimen B (g) Specimen C (g) Average of specimen mass (g) 0.2 2.12 2.23 2.39 2.28 0.4 2.24 2.12 2.10 2.15 0.6 2.23 2.23 2.15 2.20 0.8 2.14 2.13 2.26 2.18 After Concentration of sucrose solution (M) Specimen A (g) Specimen B (g) Specimen C (g) Average of specimen mass (g) Percentage difference in mass (%) 0.2 2.28 2.39 2.42 2.36 3.50 0.4 2.01 1.93 1.93 1.96 -8.83 0.6 1.54 1.70 1.57 1.60 -27.27 0.8 1.39 1.55 1.58 1.51 -30.73 Conclusion I conclude that as the concentration of sucrose solution increases the mass of the potato decreases, I also conclude the isotonic point is around 3M. My graph shows above my x axis the potato is turgid, this is because there is a high concentration of water where as the potato has a low concentration of water, osmosis is the movement of water from a high concentration to a low concentration so the potato sucks up a lot of the water. This relies on the fact of osmosis; if a cell is placed in a less concentrated solution, then in order for equalization to occur, that is for the concentration ...read more.

Conclusion

12. I will measure out 10ml 5 times of coca cola solution for each reading. 13. Using the second lot of 55 specimens, I will then put 5 specimens in for the next lot (readings are: 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M, 1.2M, 1.4M, 1.6M, 1.8M, 2.0M.) 14. 6. I will measure out 10ml 5 times of lemonade solution for each reading. 15. Using the third lot of 55 specimens, I will then put 5 specimens in for the next lot (readings are: 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M, 1.2M, 1.4M, 1.6M, 1.8M, 2.0M.) 16. 6. I will measure out 10ml 5 times of orange juice solution for each reading. 17. I will divide the 220 different specimens of apple into 4, so I will get 55 in each group. I will then put 5 specimens in for each reading (readings are: 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M, 1.2M, 1.4M, 1.6M, 1.8M, 2.0M.) 18. I will measure out 10ml 5 times of coca cola solution for each reading. 19. Using the second lot of 55 specimens, I will then put 5 specimens in for the next lot (readings are: 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M, 1.2M, 1.4M, 1.6M, 1.8M, 2.0M.) 20. 6. I will measure out 10ml 5 times of lemonade solution for each reading. 21. Using the third lot of 55 specimens, I will then put 5 specimens in for the next lot (readings are: 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M, 1.2M, 1.4M, 1.6M, 1.8M, 2.0M.) 22. I will measure out 10ml 5 times of orange juice solution for each reading. 23. Before putting the chips into the solution I will weigh them all. 24. After all the following, I will get 880 people to put the right chip in its solution at the same time. 25. I will leave the chips for two days 26. I will then get the 880 people to take the chips out at the same time and then re-weigh them on the same top pan balance and record the results. ...read more.

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