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Membrane Permeability : the effect of temperature

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Membrane Permeability : the effect of temperature AFTAB MOHAMMED Membrane Permeability : the effect of temperature TITLE 'How does temperature effect membrane permeability?' METHOD The Investigation was carried out in the following way: * Six pieces of beetroot were cut out about 2 cms long using a cork borer. * The cylinders of beetroot were placed on a white tile and using a razor blade they were cut into discs 3 mm thick. * The discs were placed in a beaker of tap water and washed thoroughly, rinsing out the beaker several times. * Test tubes were labelled for each temperature to be tested. The temperatures required were 30, 40, 50, 60, 70 and 80?c * 6cm� of tap water was put in each test tube * 6 washed beetroot discs were impaled on a mounted needle allowing space between each disc. * Mounted needle with discs was placed in the 30?c water bath for exactly one minute. At the end of this time, the discs were taken off the needle and dropped into the test tube labelled 30?c * This procedure was repeated for temperatures 40, 50, 60, 70 and 80?c. ...read more.


Between 40-50?c, the opposite happens here, my results show that the absorbance decreases but the mean results show that the absorbance increases Between 50-60?c, there was an increase in the absorbance Between 60-70?c, there was a very steep increase in the absorbance Between 70-80?c, there was an increase in both results The difference in the results at the beginning of the graph was probably due to anomalous results. CONCLUSION The graph clearly shows that as the temperature increases, the absorbency also increases. The beetroot discs were washed in the experiment to remove any anthocyonin from the surface. The colour of the liquid in the test tubes changed due to diffusion taking place. Anthocyonin diffused out from the cell into the liquid. This happened because of the big concentration gradient. The results showed that as the temperature was increased the membrane became more permeable and allowed more pigment to enter the liquid from the beetroot. DISCUSSION The cell membrane contains intrinsic proteins that control the membrane's selective permeability. ...read more.


structure. This structure accounts for the cell letting the anthocyonin out. EVALUATION Errors: * Some beetroot may have more anthocyonin than others. This is trivial though; it would not make much difference. * The beetroot discs were not measured as accurately as they seemed. They could be significantly too large or small. * The equipment used was not accurate enough. Using a pipette is not necessarily accurate; it could have produced errors in measurement. Limitations: * The whole experiment should be repeated more times to make the results more reliable * Only 6 temperatures were looked at, we could have done more * When the beetroot was stabbed to put on the needle, it could have allowed anthocyonin to come out. But this was done so that the beetroot discs don't touch one another and maximum surface area is created. * Errors could have been made when using the colorimeter, it as a machine and they can make accuracy errors. * Cuvettes had to be handled very carefully, but scratches may have already been on then and fingerprints also affect the absorbency. So in effect, these could have taken place. AFTAB Mohammed BIOLOGY SALTERS 1 ...read more.

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