Beta Vulgaris Membranes Investigation

Aim
How temperature affects membranes: investigating the effect temperature has on Beta vulgaris membranes when submerged in a range of different temperatures for one minute.

Background Information
A cell membrane is made up of a phospholipid bilayer formed by phospholipids that have a hydrophilic head and a hydrophobic tail. The phospholipids arrange themselves in order that the heads are exposed to water and the tails are not thus forming the bilayer. When the temperature increases molecules gain kinetic energy vibrating faster and water expands which damages the membrane. Furthermore with heat lipids become more fluid making the membrane fragile. In beetroot when the membrane is damaged, the red pigment it contains is released.

Variables
DEPENDANT VARIABLE Effect of temperature on Beetroot membrane / /

CONTROLLED VARIABLES UNITS POSSIBLE EFFECT(S) ON RESULTS
Surface area millimetres cubed (mm3) May affect the rate of which the red pigment from the beetroot come out
The pigment that comes out of the damaged cells when the discs are cut / May effect the results as the pigment is not caused by the membranes being damaged by the temperature but because they have been cut
Amount of distilled water in the test tube Millilitres (ml) If the amount is different the results would not be fair and would not give the correct conclusion
Time Minutes (min) Results would not be fair and would not give a correct conclusion

Method of Controlling Variables
CONTROLLED VARIABLES METHOD OF CONTROL
Surface area Every beetroot disc will be cut three millimetres thick using a ruler for measurement
The pigment that comes out of the damaged cells when the discs are cut The cut beetroot discs will be rinsed thoroughly making sure that the pigment is washed off
Amount of distilled water in the test tube By using a measuring cylinder six millilitres of distilled water will be placed in the test tubes
Time The time will be monitored by using a stopwatch to make sure all the experiments are tested in the same time
Firstly, take the test tubes and label the temperatures you are going to use; 20, 30, 40, 50, 60, 70 and 80. Then with the measuring cylinder measure 6ml of distilled water and put it in each test tube.
2. Then using the cork-borer, cut cylinders from the beetroot. Place the cylinders on the white tile and with the scalpel cut 3mm thick discs. (figure 1)
3. Place the disks in a beaker and rinse them very well in cold water for about 5 minutes. Fill and empty the beaker several times during this process.
4. Take an optical pin and place 5 beetroot discs through.
5. Prepare a water bath and set the correct temperature with the thermometer (e.g. 20°C)
6. Then using the stopwatch, place the optical pin with the discs in the water bath for exactly 1 minute. (figure 2)
7. After take them out and transfer the discs in the correct test tube (e.g. if they were immersed at 20°C then place them in the test tube marked 20)
8. Leave them in for 15 minutes.
9. Repeat steps 4-8 for all the selected temperatures.
10. After the disks have been kept in the test tubes for 15 minutes, shake the tubes so that the pigment is released