IB guides

Investigating the effect of temperature on the permeability of the plasma membrane of beetroot tissue.
Aim- To determine the temperature at which the beetroot plasma membrane is destroyed by heat.
Table of results:
Temperature of water bath(degrees Celsius)
Absorbance(au) (+ or – 0.06au)

Repeat 1
Repeat 2
Repeat 3
Mean of results.
30
0.5869
0.6029
0.5946
0.5948
40
0.4161
0.4436
0.7056
0.4298
50
0.4343
0.4077
0.4137
0.4185
60
0.3486
0.4466
0.7991
0.3976
70
1.0500
0.8146
0.8146
1.0455
Length of beetroot cylinders = 1cm
There were no qualitative results taken in this experiment, I have highlighted in green my anomalies in this experiment which I did not include when calculating the mean of my results.
When calculating my results, the calorimeter was set to 0.05au instead of 0.0au as a starting figure. For this reason, I have included another table of results showing the mean of the values minus 0.05au to make sure that I have a more accurate value which is plotted on my graph.

Tempreture of water bath(degrees Celsius)
Absorbance(au) (mean -0.05)
30
0.5448
40
0.3798
50
0.3685
60
0.3476
70
0.9955

Hypothesis: As the temperature of the water bath increases, the absorbance level of the plasma membrane increases.

Background information:
The plasma membrane and cytoplasmic membranes of plants, like those of animal cells, are composed of lipids and proteins that are often glycosylated. Likewise, the composition from one membrane type to another is highly heterogeneous. There is some evidence to suggest that the composition, particularly of the lipid component, may change in response to environmental conditions such as temperature, water stress, etc. as well as during growth, development and ultimately senescence of the cell. It is believed that these changes are required to adjust the physical characteristics of membrane structures so that they may perform their necessary physiological tasks when environmental

References: Biology for the IB Diploma –CJ Clegg (Hodder Education)