Variables
- Independent variable: temperature of the dye (water/beetroot solution)
As the temperature will be altered it is the independent variable, as I will be changing it to see its affects on the beetroots cell membranes permeability. Therefore, I will control the temperature by placing the dyes that will go in the test tubes, into water baths; this will control the temperature as water baths will remain the same temperature throughout the experiment, thus so will the dye
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Dependent variable: the absorbance of light by the beetroot pieces
I will attempt to control this by cutting the beetroot pieces the same size as different sized surface areas would affect the amount of dye released. The volume of dye I will use is also a variable as change in volume will change the dispersion of the dye thus; the amount of light absorbed by the pigments within the beetroot will be altered. The length of time the pieces of beetroot are in the water baths also affects the absorbance of light, as different lengths of time will affect the amount of dye that is released.
Furthermore, I will attempt to control the volume of water I am using as if I were to use different volumes of water in each test tube the dispersion in all test tubes would be different even if the temperature remained the same, and therefore, the amount of light absorbed by the pigments will be affected. It is also essential that I control the mass of the beetroot pieces, as if the mass was to be altered and there were less or more cells in the piece of beetroot the amount of dye released will also be altered. All of the above affect the absorbance of light by the beetroot pieces
Method:
- Firstly gather all apparatus mentioned in the apparatus section
- Collect a tile and place it on a flat surface, also collect a strand of raw beetroot, and cut the beetroot into 4 equal sizes of 4 cm’s using a scalpel (measure slices of beetroot using a cm ruler. The beetroot strands must be the same size to make the experiment fair as different sizes will give different results even in the same temperature.
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Take a water baths and plug them in and set each one for the 4 desired temperatures.
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Place the 1 beetroot samples in a beaker of distilled water, leave them for 5 minutes to wash away any excess dye, use a stopwatch to check the time.
- In the meantime collect test tubes and fill them each with 5cm3 of distilled water and label them with a marker pen, with the temperatures that you will be testing.
- After 5 minutes insert the raw beetroot samples into separate test tubes and fill the test tube with 5cm3 of distilled water.
- Now place the labelled test tubes each in a water bath of different temperatures and leave them all for 15 minutes, also check the time with a stopwatch, you must start the timer as soon as the test tubes are in the water bath, as if you are to start the timer too early or too late there may be a variance in temperature which would cause unreliable results to appear.
- After around 14 minutes, place a thermometer in the test tube to check if the distilled water in the test tube is the desired temperature.
- After 15 minutes have finally past, take out the test tubes from the water bath.
- From each test tube take, in accurately 2cm3 of water from the test tube using a pipette and pour the dye solution into a cuvette.
- Set the colorimeter to read 0 absorbance for clear water, the setting must not be altered again during the whole experiment as this could cause inaccurate results for example if the colorimeter starts at 10 instead of zero the readings that you take will be of a absorbance of 10 more than it should be, which will give you unreliable results.
- Place the cuvette into the colorimeters slot and place the black cap on top, so that no light may enter, you must do this as if light were to enter this may cause unwanted fluctuation in your results as the light intensity will alter the absorbance.
- Now check the reading and note it down, this is the absorbency of the dye solution at that particular temperature.
- You must do all the above again for each temperature that you are experimenting.
Results
Conclusion
From the table of results that i have collected and the graph that i have drawn i can see, that as the temperature increased, the amount of light absorbed by the pigment in the beetroot also increased, this is clearly indicated by the steepness of the graph as the line of best fit’s steepness goes higher across the x-axis. Furthermore, by simply looking at my tables i can see that my results are consistent as there is not a great difference between all of my results for example in my table for the temperature of 20 degrees Celsius most results were within a 10 degrees range. The aim of my experiment was to see whether temperature affects membrane structure and my results show that it does, because as the temperature increases the transmission increases to. As the temperature increased i realised that more membrane broke down this suggests that more dye was released from the beetroot.
An increase in temperature does cause an increase in the amount of dye released from the beetroot. This is due to the increase in heat denaturing the phospholipids bilayer, so the betalain in the vacuole (the pigment) is able to diffuse out of the bilayer more readily.
n the plant, and enter through simple diffusion. Once inside the plant the nutrients can reach the stele through one of two methods. One of the methods is the use of the apoplast pathway, this involves soaking through the cell wall into the cell, once here it soaks into the next cell via the plasmadesma or pits found along the cell membrane, and continues this method until reaching the endodermis. The second methods available for use is the sinoplast pathway in which the nutrient soaks in and then out of the cytoplasm of each cell , continuing to do so until it reaches the endodermis.
Evaluation
My results are fairly accurate and this is shown by the closeness of the six sets of results. From the graph i can see that my results are accurate and reliable as i do not have any outliers in my averages, i know this as all of my points are close to the line of best fit, suggesting they are too different compared to my other results. Although it seems that a few outliers are quite a lot, it must be mentioned that i did this experiment many times, therefore, there is more chances of getting outlier results within my trials.
However, I do realise that any big differences in my results for example in the experiment trial 1, the heart rate in the distilled water group varies greatly from 62 to 89, this may have happened as I had to take each piece of beetroot out and this took me a little while. It could also be because the temperature may have fluctuated slightly over time meaning that the water bath wasn’t exactly the same temperature throughout the experiment. Additionally, in each of my tries in the tables, as you go down try 4 the transmission increases whereas on all the other tries the transmission decreases as you go down the try and thus with higher temperatures, i believe these are outliers due to
I believe the procedure in which i carried out the experiment was quite precise; however, if I were to redo the experiment again I would do it on different beetroot samples as the beetroot sample i used may have been contaminated which may have affected the transmission and thus the reliability and accuracy of my results. Furthermore if i was to redo this experiment i would also a greater variance in temperature for example the temperatures i used mainly went up by around 10 degrees, but if the temperatures went up by 5 degrees i would be able to have more precise and accurate results as i would get a better average and would make my conclusion more secure.
Moreover, as another improvement to my experiment i would leave the sample of beetroot in the beaker of distilled water for more than 5 minutes to remove any excess dye, i would do this because in 5 minutes i do not believe that all the excess dye would be removed so if i were to redo this experiment i would leave the beetroot in the dye for 1 day, it is important to wash off any dye, as any excess dye will affect the transmission thus, giving me outliers in my results. I could also do more work by seeing how pH level affects membrane structures. For me to be able to do this I would leave the beetroot in different pH’s for 30 minutes and then use a colorimeter to measure the light absorbed by the dye that has been released from the beetroot.
All in all, from this experiment i have learnt that an increase in temperature breaks down the membrane structure which in turn causes an increase in the amount of dye released from the beetroot.