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Investigate the osmosis in Potato rods when they are put in different Concentrations of salt solutions.

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To investigate the osmosis in the Potato rods when they are put in different Concentrations of salt solutions I. (PLANNING( My aim in this work: My aim is to find out if changing the concentrations of salt solutions will affect the osmosis in the potato rods when they are put in different concentrations of salt solutions. Introduction: Osmosis is the movement of water molecules across a partially permeable membrane from a region of high water potential to a region of low water potential. It can be affected by several different variables including concentration of salt solutions. When a plant cell is put in pure water it will become turgid and it will not burst due to the presence of a cell wall and a large permanent vacuole and when it is put in a concentrated solution it will be plasmolysed, on the other hand when an animal cell is put in pure water it will burst due to the absence of the cell wall which is only present in the plant cell and if is plant cell is put in a concentrated solution it will shrink. What is the water potential? The water potential of a solution is a measure of whether it is likely to lose or gain water molecules from another solution. A dilute solution, with its high concentration of water molecules is said to have a higher water potential than a concentrated solution, because water will flow from the dilute solution to the concentrated solution (from a high water potential to a low water potential).: Pure water has the highest water potential because water molecules will flow from it to any other aqueous concentrated solution even if this solution is a highly dilute solution. ...read more.


length and firmness depending on the water potential difference between the potato and the solution, if I am lucky enough I will find no change in length in some potato rods, this will show the water potential of the potato which will be equal to the concentration. Precautions: (a) For personal safety: ? to conduct my experiment safely I will follow general normal laboratory rules, which include: ? the wearing of safety goggles to protect my eyes in case any solution would not enter my eyes. ? Taking care when handling chemicals or solutions. (b) In order to make my results accurate: ? Leave the conical flasks for about 30 minutes before adding solutions to the test tubes in order to have same initial temperature and that is the room temperature. ? Dry the potato rod by the filter paper before weighing it and before putting it in the solution. ? Don't touch any equipment that is being obscured so as not to make it break down or fall. ? Start the stopwatch at the exact time as we put the potato rods in each test tube. ( I got an assistant to help me) . ? Repeat each experiment two times to get the average time to have better accuracy and better results. * Use separate syringes for different salt solutions so that they won't mix. * Handle the potato rods gently by using the forceps and not by our hands as our hands may be sweated. Sources of knowledge: ? Http://www.edexcel.org.uk ? Dr. Mohammed Emad's Biology lectures and tutorials ? Biology GCSE book by D.G. Mackean. ? The program used in drawing the balance and tools: Microsoft (r) ...read more.


I could feel that all the work I have done was good and my results were also good, as there does not appear to be any anomalies or any sources of error in my experiment and the results were near what I was expecting. The graph made the patterns more clear and the results much more obvious. IV. (Evaluating Evidence( My experiment went according to my plan, which I made. I could feel that my results are good in their accuracy and the points on the graphs were plotted as accurately as possible practically. All my results supported my prediction I made and helped me to make a strong trend in the graph. Although, I might have got few anomalous results but that is to be expected, I may be have measured any substance which I am using wrong or not accurately. I repeated the experiment two times to get the accurate average results and to ensure that I had not made any mistakes and so as not to have any anomalous results in my experiment and there wouldn't be any chance for error to occurs. My results seem reliable as I am basing my results' reliability on a hypothesis and my own prediction. I repeated the same experiments using different concentration of the salt solution or change the temperature so as to help the rate of osmosis in the potato rod. Also for more accurate results, I could extend my coursework by testing the same brand of potatoes using different substances. By this I mean using a different thing instead of salt, i.e. sugar or maybe any fruit juice. Then I could find out whether osmosis occurs differently with different things diluted in the water. I could even use different vegetables and fruits. - 1 - O.L. Biology Page 1 / 9 Coursework ...read more.

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