The optimum temperature of the beetroots normal working conditions should be around 40 °C as the optimum temperature for animal cells is 40 °C, therefore I assume that the beetroot should be around that temperature due to similar living conditions of both organisms. Therefore if the temperature goes above this optimum temperature then the proteins in cell membrane of the beetroot will become denatured and anything can enter or leave the cell. A good indication of this easy diffusion, due to denatured proteins, would be the amount of red dye that diffuses out of beetroot. This is what the experiment is investigating.coef efr seefefw oref efk inef foef ef.
Prediction
Referring to background knowledge, I can predict that an increase in temperature beyond 40 °C will increase the permeability of the beetroot cell membrane. Therefore I predict that more red dye should be present outside the beetroot at a temperature of 70 °C than there would be at a temperature of say 50 °C.
Equipment list and why using it: Weber refuted abidzaman's rationalisation hypothesis.
Diagram of equipment
Plan
The variable that will be changed in this experiment will be the temperature of each water bath. The steps of each measurement will be 30, 40, 50, 60, 70, 80, 90 and 100 degrees centigrade. I have chosen these steps because I have predicted that 40 °C will be the optimum temperature for the beetroot and will indicate little red pigment diffusing out of the beetroot therefore showing if the cell membrane has kept its integrity. Referring to my prediction 30 C should show the temperature being to low for the proteins to work properly, and as a result show little permeability in the cell membrane. The other temperatures beyond 40°C will show the beetroot being denatured, with more red pigment as the temperature increases, diffusing into the distilled water. I will change the temperature by heating up the glass beaker, which contains water acting as the water bath and the 3 boiling tubes containing distilled water, to the desired temperature using a Bunsen burner. I will use a thermometer to check what the temperature of the water is, making sure the temperature of the water bath is accurate. When the water has reached the specific temperature I will then remove the Bunson burner, add the three beetroot pieces to the boiling tubes then start the stopwatch. The factors that will have to stay constant throughout the experiment are:
- pH of the water in which the beetroot is in. This is because pH is a factor that can affect proteins in a similar way to what temperature can, it breaks the hydrogen bonds in the proteins if too alkaline or acidic, denaturing the proteins. Therefore this has to stay constant to make sure it does not denature the proteins in anyway, consequently we will use distilled water, which has a constant pH of 7.
- Surface area of the beetroot, as a difference in surface area of the beetroot pieces will cause different beetroot pieces to have more membrane exposed to the water in the water bath causing easier diffusion of the red pigment out of the beetroot. Each beetroot piece will be 1 cm long, measured by a ruler, and have the same diameter using the same cork borer.
- Amount of water in the boiling tubes, 20 mm of distilled water will be in every boiling tube. This has to be the same in every boiling tube otherwise if there was more distilled water in one boiling tube compared to another one then that red pigment in the boiling tube with more distilled water in would be more diluted. This work from www.coursework.info
- Time in which the beetroot is placed in the water bath for. If the time that each beetroot piece is in the water bath for varied then more or less red pigment will be lost by the beetroot just because it has been in a certain temperature for longer not just because of the temperature itself, which is what we are measuring. Therefore we will keep each beetroot piece in the water bath for exactly 5 minutes.
The way in which I will collect this data is by using a colorimeter. This is a digital piece of equipment, which measure the optical density of a substance, which has been placed in a cuvette. This means how much light the substance absorbs and is measured in arbitrary units. It comprises of a lamp, filament that will be blue, a photosensitive element and a digital display. The substance is added from one of the boiling tubes into a cuvette, holding the cuvette on the 'grooved' side so that no finger marks will affect the reading, the cuvette is then placed into the colourimeter with the notch facing forwards. The light should therefore shine through the clear sides on the cuvette. As the colorimeter is measuring how much light the substance in the cuvette is absorbing it obvious that the more red pigment that is in the cuvette the more light it will absorb as the substance is of a higher density because there is more pigment. To make sure the colorimeter is set up the same for each cuvette we put into it for a reading I will put a cuvette filled with distilled water in, in first and set the colorimeter to zero. When cutting up the pieces of beetroot in the first place the membrane of part of the beetroot will be broken resulting is red pigment being lost. This acts as excess pigment, which we do not want to measure and therefore we would need to get rid of it. The best way of doing this is the rinse each piece of beetroot that you have cut under distilled water, this will get rid of that excess pigment and therefore you will only measure the red pigment that has been lost in the boiling tubes. Keeping an eye on how long the beetroot is in the water bath for is also important, as already stated earlier in the plan. Making sure that you don't get any finger marks on the cuvettes when using the colourimeter is also important because if any marks get on the clear sides of the cuvettes the cuvettes will be darker and therefore more light will be absorbed. Also making sure that you read the reading of the thermometer at eye level will make sure that you record the reading correctly.
I will do 3 replicates for each measurement i.e. there will be three boiling tubes in a specific water bath. Doing this will enable me to take and average of all replicates and therefore discounting any anomalous results.