Beetroot practical

• I left the beetroot pieces in a beaker of distilled water for one night.

• Next day I placed the beetroot pieces into tubes of 5 cm of distilled water and placed them into different baths with different temperatures between 0-70.

• After 30 minutes I collected 2cm3 fluid from each water baht.

• The fluid in each of the test tubes was analysed using a colorimeter

The variables kept constant

•  The same diameter corer is used so to keep the surface area of each beetroot piece  the same size.

• When the beetroot has been cut some of the cell membranes broke, which means some coulor leaked out.

• I used distilled water so that I had a reliable substance to test with a colourimeter.

After completing the experiment I drew my results, wrote my discussion and evaluation to determine what exactly happened.

                        (see graph next page)

Analysis

Through observation from the line graph that I have constructed it is quite certain that there is a similar pattern. There is a steady speed increase represented by a positive correlation. It shows that as the temperature increases the percentage of absorbance also increases. This means that more pigment diffused through the beetroot’s cell membrane at higher temperatures. There is one exception, which is the beetroot that was situated within the cold water as this shows an absorbance of 0%.

Evaluation

There were a number of sources of error that may have affected the accuracy of my results. Firstly I had one stopwatch and timed all the water baths for fifteen minutes, so there was a slight delay however between the placing of the tubes in each water bath, as I had to walk to each water bath so it would have affected my reults slightly. This would only have had a small effect on my results, because the vacuole of the beetroot would have only released slightly more betalain, as the molecules would have only had a very small amount more heat energy to convert into kinetic energy.

Secondly I when I washed each of the beetroot pieces I may not have removed all of the red pigment on the outside, so this would have affected my results very slightly. Again this would only have had a small effect on my results, because a very slight increase in betalain molecules would not have changed the reading on the colourimeter.

There were also limitations of my experiment. Firstly I only had an hour to do my experiment- this did not give me time to collect a suffient number of results. A larger number of results taken at different temperatures between 20oC and 60oC would have allowed me to find out more accurately where the point of denaturation occured.

It would also have been better to have had the time to repeat each temperature more times to make the results more reliable.

Another limitation was cutting the beetroot into pieces. The pieces cut had roughly the same surface area to volume but not exactly the same volume. This would have had a slight effect on my results because the rate of diffusion of betalain particles across the plasma membrane is increased, as the surface area of the beetroot increases. So the slightly thinner and smaller pieces of beetroot I cut would have released more betalain from their vacuole.  

Conclusion

I conclude that there are no apparent anomalies in my results and none of my sources are deem enough to make my results unreliable. However the sources of error and limitations in my results may have made my results slightly less accurate, but other students in my class found the same.