The effect of temperature on cell membrane permeability in beetrootAim: To observe the effect of temperature on the colour of water samples containing beetroot. The intensity will be measured to determine the permeability of the beetroot cell membranes at differing temperatures. Apparatus: The equipment used to obtain our results included: Six test tubes A test tube rack A cork borer A white tile A scalpel Distilled water A small beaker A graduated pipette A mounted needle Large beakers 4 water baths A kettle Thermometers Safety goggles Measuring tape A stopwatch A colorimeter Risk Assessment: There was no serious risk in this experiment as long as all of the equipment was handled properly. Incorrect usage of the kettle or the scalpel could have possibly resulted in cuts and burns. To prevent such instances from occurring, boiling water and the sharp edge of the scalpel should be handled with caution and used sensibly. Method: Firstly, the cork borer was used to cut cylinders of the beetroot. These cylinders were placed on the white tile where they were cut into 36 equal pieces (3mm) to ensure that they had the same amount of mass, volume and surface area as possible. Once the pieces had been cut, they were placed into a beaker under running water. This was to preserve the cells and wash any dead cells off of them too.The next step was to prepare the water baths at 30C, 40C, 50C and 60C using a thermometer in each individual bath to measure each individual temperature. The boiling water was prepared using the kettle (filled with distilled water) which would then later be put into a beaker. Room temperature was recorded in an empty beaker.The test tubes where then labelled according to what temperature they would sit in for 20 minutes.Using the pipette, we added 6cm of distilled water into each test tube, then put 6 beetroot pieces on a needle for each test tube (with spacing between each beetroot sample).We then placed all of the appropriate test tubes into their respectively labelled water bath temperatures, boiling water or room temperature. The stopwatch was used to measure 20 minutes that each test tube would sit in their temperatures for. After the 20 minutes was up, the test tubes were removed from the different temperatures, the needles with the beetroot pieces were then removed from the test tubes to leave just the water in them. Finally, the test tubes were placed on the colorimeter and the units displayed for light intensity were recorded whilst a test tube with distilled water was used between each measurement as a start point. Results: Temperature (C)Coloration (ABS)

Boiling water60504030Room temperature2.001.170.910.320.230.18

Conclusion: The results prove that as the temperature increases, the coloration of the water samples increases. This shows us that as the temperature increases, so does the permeability of the beetroot cells. The higher temperature results in the proteins within the membrane having more kinetic energy, the hydrogen bonds that hold together the amino acids will untangle and break away from the membrane. The resulting wholes left in the cell allow pigments to diffuse out of the cell and into the water, the more pigment in the water, the more red/purple it will become. This means that the more coloured the water sample, the more permeable the membrane was, this holds true as the boiling water sample was a strong red/purple whilst the room temperature was a weak red at best.

Haider Bukhari.