This experiment aims to determine what effect an increase in the surrounding temperature has on the cell membrane of a beetroot cell.

Discussion

My results showed that an increase in temperature will damage and denature the membrane.  This has been shown by a steady increase in anthocyanin ( the red dye in the beetroot) leaked out of plant cells as the temperature increases.  The percentage of light passed through the liquids increase fairly steadily with one exception at 60 oc where the percentage increases from 47% to 75%.  This is almost certainly due to experimental error.  

It is the breakdown of the lipids which make up the plasma membrane that causes 'holes' to appear in the membrane, allowing fluids to pass out freely, but when the temperatures begin to get higher still, the proteins in the cells begin to decompose as well, meaning the release of anthocyanin increases as the temperature raises.  This explains my results because as the temperature increased the amount of light let through decreased, meaning more anthocyanin was being released from the cells in the beetroot .  

It would have been beneficial to have repeated the experiment more times to make certain that the results were not gained through chance or by an external factor.  Controlling the variables in the experiment is not an easy task.  The first major problem is the size of the beetroot piece.  The pieces could be the same mass, but have a very different surface area to one another.  This obviously alters the effect of the experiment.  The other difficult variable to maintain was the temperature of the heated water.  With only basic equipment, keeping the water at the correct temperature was made a complicated task.  If the experiment was to be repeated, the use of a proper controlled water bath may be a consideration, and also a template made for cutting the beetroot pieces.  Using a beetroot as the sample is not a good representation of the whole plant group.  Other cell membranes may have better or worse heat tolerance, some may not be affected at all, however, using a beetroot does give a good representation of the theories behind the cell membrane and how it behaves with heat.

Conclusion

In my hypothesis I predicted that as the temperature increased the amount of dye let out of the cells will also increase, leading to a reduction in the amount of light let through the substance.  As you can see for my results and graph as the temperature increases the percentage of light let through decreases.  This is because as the temperature rises it causes the breakdown of the lipids which make up the plasma membrane. This then causes 'holes' to appear in the membrane, allowing fluids to pass out freely, but when the temperatures begin to get higher still, the proteins in the cells begin to decompose as well.  Meaning that anthocyanin will be released into the surrounding water, changing the colour.  This means the water from the higher temperatures will be darker in colour leading to less light passing through them, which means the colourimeter will show a low percentage of light detected.  For example 70 oc only lets 40% light through.

 

Results