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An experiment to find of the isotonic point of root vegetables cells in contents using osmosis

Extracts from this document...

Introduction

Centre number: 20603 Candidate number: 1216 Name: Mohammed Zafran An experiment to find of the isotonic point of root vegetables cells in contents using osmosis Aim - I am going to investigate how different concentrations affect root vegetables finding the point of balanced osmosis, as this will be the isotonic point where the amount of water diffusing into the cell is equal to that diffusing out of the cell hence at this point equilibrium will exist and the isotonic point will be obtained. Therefore when I obtain my results and plot them on a graph the point at which they intercept the x-axis, will be my isotonic point. As the isotonic point is the point in which the net movement of water is equal therefore as I know that the mass is affected by the water content present in the cell. Therefore I will plot the values for my % mass increase/ decrease to find the isotonic point for each root vegetable. The x- axis will have the different concentration values; the y-axis of my graph will have the % change. As the my line of best fit intercepts the x-axis this will mean that my percentage change will be 0% and therefore at this concentration the isotonic point for my root vegetable will be obtained. Equipment required for the practical investigation. * 24 McCartney bottles will be used- These will be used to contain the various concentrations of sucrose solution and the vegetables over the 24 hour period of time. They will be covered with a lid to prevent evaporation. They are used in preference to Petri- dishes as I realised that Petri- dishes lids were not tightly attached to the Petri-dish therefore in my preliminary work my results had a source of error. To increase the reliability and precision of my results McCartney bottles will be used as they have a tight filling lid which will minimize evaporation. ...read more.

Middle

0.3 0.4 0.5 0.6 0.7 Before After Before After Before After Before After Before After Run 1 1.43 1.48 1.37 1.39 1.48 1.46 1.46 1.40 1.53 1.45 Run 2 1.45 1.46 1.45 1.49 1.45 1.44 1.44 1.41 1.43 1.36 Run 3 1.47 1.48 1.53 1.52 1.41 1.39 1.43 1.35 1.48 1.39 Mean 1.45 1.47 1.45 1.46 1.45 1.43 1.44 1.38 1.48 1.40 Difference (g) 0.02 0.01 -0.02 -0.06 -0.08 Percentage Change (%) 1.36 0.68 -1.38 -4.43 -5.41 Length of Swede cylinder Solution (Molar) 0.3 0.4 0.5 0.6 0.7 Before After Before After Before After Before After Before After Run 1 30 30 30 30 30 28 30 27 30 26 Run 2 30 32 30 29 30 29 30 26 30 27 Run 3 30 31 30 31 30 30 30 29 30 26 Mean 30.0 31.0 30.0 29.0 30.0 29 30 27.6 30 26.7 Difference (mm) 1.00 -1.00 -0.3 -2.40 -3.30 Percentage Change (%) 3.23 -3.33 -3.33 -8.00 -11.00 Parsnip Mass of parsnip cylinder Solution (Molar) 0.3 0.4 0.5 0.6 0.7 Before After Before After Before After Before After Before After Run 1 1.36 1.37 1.27 1.21 1.33 1.27 1.29 1.18 1.35 1.16 Run 2 1.30 1.31 1.22 1.19 1.29 1.23 1.22 1.14 1.32 1.18 Run 3 1.30 1.34 1.20 1.17 1.23 1.16 1.27 1.19 1.22 1.17 Mean 1.32 1.34 1.23 1.19 1.28 1.22 1.26 1.17 1.30 1.17 Difference (g) 0.02 -0.04 -0.06 -0.09 -0.13 Percentage Change (%) 1.49 -3.25 -4.69 -7.14 -10.00 Length of Parsnip vegetable cylinder Solution (Molar) 0.3 0.4 0.5 0.6 0.7 Before After Before After Before After Before After Before After Run 1 30 30 30 29 30 29 30 23 30 25 Run 2 30 31 30 30 30 27 30 24 30 26 Run 3 30 31 30 29 30 29 30 23 30 25 Mean 30.0 30.67 30.0 29.33 30.0 28.0 30.0 26.66 30.0 25.33 Difference (mm) ...read more.

Conclusion

Therefore the mass that I recorded may still have had some water present due to poor drying and therefore the mass I recorded will be inaccurate. To obtain a more accurate mass and ensure that no water is present on the root vegetable cylinder I will use a hair dryer for 2 minutes for drying each root vegetable. By using the hair dryer for the same time period will ensure that the same amount of water is removed from each root vegetable cylinder and therefore a more constant mass will be obtained for each root vegetable. This in turn will make my results more accurate because by using a paper towel for drying different amount of water will be removed by using a hair dryer at the same level for the same time will ensure that a more accurate end mass is obtained this will therefore improve the accuracy of my results. To obtain a more accurate mass I will use a electronic balance which goes to 3 decimal places, the one which I used for my actual practical went to 2 decimal places, due to this I may obtained an inappropriate mass resulting in me obtaining a few inconsistent results. Therefore by using a 3 decimal place electronic balance a more accurate mass will be obtained, which will therefore increase the reliability and precision of my results because a more accurate end mass will be obtained. Even with the anomalous results I can accept the validity of my results because although factors may have occurred which were out of my control, but the results I obtained show the trends and patterns that I expect although there are a few exceptions in my results in the term that anomalous results exist. By examining my results and the procedure used to carry those out I accept the validity of my results as the procedures experimental errors that occurred were out of my control. Overall my results are correct and the few anomalous results do not affect the validity of them. ...read more.

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