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Investigation of osmosis in potato strips by measuring the length of the strips after a incubation in various sucrose concentrations

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Introduction

Name : Rand IshaqBiology lab report2011-09-19 Investigation of osmosis in potato strips by measuring the length of the strips after a incubation in various sucrose concentrations Aim: the aim is to investigate the effects of Osmosis through selectively permeable membranes (potato cells) when placed in different solute concentrations for 30 minutes. Research question: how do different solute concentrations after 30 minutes incubation affect the length of potato strips? General background: in living organisms. The processes of diffusion and osmosis happen frequently as means of cellular passive transport. Firstly diffusion is the random movement of molecules from an area of higher concentration of those molecules to an area of lower concentration, while osmosis is a special case of diffusion. Osmosis is the diffusion of water through a selectively permeable membrane that allows for diffusion of certain solutes and water) from a region of higher water concentration to a region of lower water concentration. When two solutions have the same concentration of solutes. They are said to be isotonic in relation to each other. If the two solutions are separated by a selectively permeable membrane. Water will move between the two solutions. But there will be no net diffusion of water between the two solutions resulting in, that the concentrations will remain the same in relation. ...read more.

Middle

3 : the table shows the mean initial length of potato strips, the mean final length after the incubation in different sucrose solutions and the change in length (change in length = mean final length ? mean initial length )in addition it shows the standard deviation of the mean final lengths using excel : Concentration (mol dm-3 ) mean Final length (cm) Mean initial length (cm) Change in length (cm) S.D (cm) 0.0 4.1 4.0 0.1 0.11 0.2 3.9 4.0 -0.1 0.11 0.4 3.8 4.0 -0.2 0.10 0.6 3.7 4.0 -0.3 0.08 0.8 3.6 4.0 -0.4 0.07 1.0 3.5 4.0 -0.5 0.08 Graph (1) the graph shows the change in the length of the potato slices after the incubation in different sucrose concentration for 30 min.: Best fit line The solutions are isotonic (0.15 mol dm-3) Conclusion and evaluation: The results obtained from the experiment support my hypothesis. By osmosis , water molecules diffused into or out of cells of the potato strips since they are a collection of thousands of cells all stacked on one another that are surrounded by partially permeable membranes. The concentration of sucrose solution affected direction of the movement of water. The potato strips decreased more in length, the higher the concentration of sucrose in the surrounding solution was in the beaker, and on the other hand the potato strips increased more in length, the lower the concentration of sucrose in the solution in the beaker surrounding the potato strips. ...read more.

Conclusion

would give a more clear result Assuming that the sucrose concentrations were as stated on them and not making sure that they have the same concentration as stated on them Make sure that the ( sucrose concentrations) have the same concentrations as stated on their labels by making the concentrations by our selves Undertaking the experiment one time only because the shortage of time of the lesson Repeating the experiment twice or three times to insure the results obtained. Only 6 data points were taken and a small range of data was used because of the limited time of the lesson use a larger range of data and approximately 10 data points and a wider range of sucrose concentrations in order to get a more accurate results The apparatus used to measure the time of the incubation was a normal cellphone Using a more accurate apparatus to measure the time for example a( stopwatch ) and all the potato strips shall be drained and measured at the same time. Mass of the potato strips was not measured Mass of the potato strips should be measured in order to have more clear and certain results. In my experiment the surface area of the potato strips differed and was not all the same. this might resulted into different rate of osmosis in the potato cells ...read more.

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