Temperature On The Movement Of Rigment Through The Cell Membranes

Figure 1 showing cell membrane structure

From the graph it is evident that as the temperature increases, the % transmission of light through the solution(distilled water and anthocyanin) decreases.Therefore it can be deducted that temperature is one of the factors that affect the diffusion of anthocyanin because the amount of anthocyanin diffused in the distilled water was dependent on the temperature level the sample was in, for example at 45°c,the % light transmission was 99.4%(0.6% absorption) on average whilst at 85°c the %light transmission was 54.4%(46.6% absorption) on average, this shows that the distilled water became more concentrated for samples that were on higher temperatures than the ones at lower temperatures.

According to theory, the higher the temperature, the faster the diffusion, so the high temperature caused the molecules of the anthocyanin to move faster from a region of high concentration(beetroot cell vacuole) to a region of low concentration(distilled water) until equilibrium is reached. As shown in Fig1, the plasma membrane is made of a phospholipid bilayer which consists of hydrophilic phosphate heads and hydrophobic fatty acid tails. So the phosphate heads form the two outer parts of the plasma membrane as they are attracted to water whilst the fatty acid tails form bonds with each other in the inner part of the membrane as they repel from water. It also consists of integral proteins which could act as enzymes,as the temperature rises to 85°c,they were denatured thus creating holes for the anthocyanin to diffuse easily.

Therefore, to a certain extent, temperature has an effect on the movement of pigment through the cell membranes. The higher the temperature,the more integral proteins are denatured,as a result more holes are created thus speeding up diffusion.

EVALUATION

WEAKNESSES

SOLUTION

1.the beetroot roots were not precisely of the same size. This could have affected the rate of diffusion and the amount of anthocyanin released in the distilled water. If one of the roots were larger, there would be a higher area for diffusion,thus speeding it up and more pigment would be released as it would have more cells and vacuoles containing the pigment. This would defy the rule of keeping all but one variable constant and the experiment wouldn’t be fair.

1. this problem could be solved by using special sharp cutting tools like scalpels for cutting the beetroot roots and using a microgauge to accurately measure the sizes of the beetroot samples. So there should be special time allocated for the measuring of all the beetroot discs that will be part of the samples.

2.the volume of distilled water in the different test tubes was not equal. This would have affected the correct concentration of the solute. If there was more water in a test tube, the concentration would have been less than it should be thus disrupting the whole experiment as the variable is not held constant.

2.a pipette could be used for accurate and precise measurement of the distilled water in the test tubes and for measuring the solutions measured on the colorimeter.

3. when the test tubes were being shaken so that the settled anthocyanin spreads evenly, there was no standard for shaking, so some test tubes must have been shaken more than others, resulting in inconsistency of variables again, thus giving inaccurate results.

3. a centrifuge like the one shown in Fig.2 could be used to shake all the solutions evenly so that the variables are constant for all the solutions.

4. sometimes the cuvettes would get wet and disturb the readings of the colorimeter,the cuvettes could have also been scratched thus disrupting the transmission of light and giving wrong readings.

4.an automated colorimeter could be used to tackle this problem as one does not need to insert and remove cuvettes by hand,thus greatly reducing the problem of scratching and wetting the cuvettes. A flowcell is fitted through which the solution flows continuously.

5. it was difficult to remove the beetroot cylinders from the test tubes on time because the circumference of the discs was almost equal to that of the test tube,so the discs would get stuck inside whilst trying to retrieve them with a mounted needle.this added to the time the disc should have stayed in the test tube, thus giving wrong results as the variable was not constant

5. discs with a smaller equal circumference could be used so that the disc is easily retrieved on time.

6. there was no control experiment against which i could compare my results to establish that temperature increase was responsible for increased diffusion of anthocyanin out of the cells.

6.a control could be provided. A beetroot disc in the distilled water without heating it for 30 minutes could be used as control.

7. Pooling the data caused high standard deviations as each student might have carried out the experiment in a slightly different way,thus making the mean unreliable

7.this could be solved if each student conducted a particular number of trials themselves so that the data obtained can be consistent thus giving a more reliable mean with low standard deviation.

Figure 2 showing a centrifuge for shaking solutions

References

www.ga.gov.au/…/hydrogeochemistry-laboratory,

Wikipedia.

http://www. en.wikipedia.org ,www.micro-ox.com