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Biology Beetroot Coursework

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Aim: To find out how the permeability of cell membranes is affected by different temperatures. Objective: The objective of this experiment is to examine how a change in temperature will affect the permeability cell membranes. In this experiment, beetroots will be used to test out the aim. Background information: Beetroot cells, like all other cells, have a cell membrane. The cell surface membrane is the boundary between the cytoplasm in the cell and the environment, so it has the important job of controlling the movement of substances in and out of the cell. The cell surface membrane is composed of many components one of which is phospholipids. A phospholipid is composed of 2 main parts, a hydrophobic head which is attracted to water and a hydrophobic tail which is repelled by water but mixes readily with fat. The hydrophilic heads point towards both inwards towards the cell cytoplasm and outwards towards the aqueous external environment. The hydrophobic tails point into the centre of the membrane. The plasma membrane is also made up of proteins which are arranged randomly across the cell membrane, unlike the phospholipids which are arranged in a pattern. ...read more.


Prediction: I predict that as the temperature increases, the beetroot will become more permeable and will release a higher concentration of red pigment called betalain. This permeability will be detected due to a colour change from light to dark purple. Justification of Prediction Justification of Method I conducted an experiment to test out the hypothesis and to prove the prediction to be true or false by using one specific process. There are many ways I could have used to do this but I had chosen not to. All living organisms are surrounded by membranes, so I had a wide choice of sources to choose from. I had access to beetroot, potato, carrot and liver. I decided not to use potato because, although it is cheap and readily available, it tends to break down very quickly, and this is shown in the dark colour it changes into. This means that the potato cells will have begun to deteriorate and would not give me very accurate results. I decided not to use liver as the source because it loses mass very rapidle. Apparatus needed: * Water tank * 6 Test Tubes * A Test Tube Rack * 1 Whole Beetroot * Sharp Knife * Ruler * Scalpel * Forceps * Tile * Spatula * Calorimeter * Cork Borer (Size 5mm diameter) ...read more.


10) Gently mix each of the test tubes for a few seconds (making sure that each tube is mixed for the same amount of time to ensure accuracy of results) so that the contents of the liquid are evenly distributed. 11) Now the liquid can be separated from the beetroot disc. This can be done by using a syringe and placing the liquid into a cuvette, making sure that all the tubes are the same size. 12) Use a calorimeter to measure the absorbance of each cuvette compared to the absorbance of just plain distilled water and this will give a distinct comparison to show different absorbencies using different temperatures. The calorimeter will ensure that precise, numerical readings are taken. 13) Repeat the experiment 3 times for each of the different temperatures to ensure that the results are reliable if the results are similar. Variables Variable Why it must be Controlled How it will be Controlled Size of the beetroot To ensure that the test is fair. A graduated ruler and scalpel will be used to measure out 5mm width for each of the beetroot discs. Also, the same size cork borer (5mm) will be used to cut all of the discs. Page 1 of 4 Permeability of Cell Membrane Shaheen Munshi 62B In Beetroot Cells ...read more.

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