Beetroot Experiment

Total words: 1257

I predict that as the temperature is raised the number of molecules that are able to leave the cell and come into the solution will increase, however I think that there will be appoint at which the amount of molecules coming out will remain constant.

Red beet tissue contains large amounts of betacyanin, a red pigment, located in the large internal membrane vacuoles. When the membrane is damaged, the pigment can cross the vacuole membrane and cell membrane. Since pigment is water soluble and not lipid soluble, it remains in the vacuole when the cells are healthy. If the integrity of a membrane is disrupted, however, the contents of the vacuole will spill out into the surrounding environment. This usually means the cell that made the vacuole is dead.

Variables.

Age of beetroot.
The age of the beetroot needs to be controlled as to prevent inaccuracies. The older the beetroot the more betacyanin and anthocyanins molecules present. This will therefore make the experiment unfair, because the more pigment molecules present the more pigment molecules that can move out of the cell. Therefore the beetroot used should be freshly cut.

pH
The pH is also an important factor, as pH can have an effect on the weak interactions and bonds that bound the membrane together. To keep the pH constant it is important to make sure that the same surrounding are used for the experiment.

Surface area.
The surface area of the beta vulgaris is another important factor as the greater the surface area of the beta vulgaris, the greater the concentration of pigment molecules the beta vulgaris will hold. It is therefore important that all the pieces of beta vulgaris used be of the same length and diameter

Light intensity.
It is important that the investigation is carried out in the same light intensity because the absorption will be different for different intensities.

Colorimeter.
The same colorimeter should be used throughout the experiment to make sure that the accurarcy to which the results are given are of the same degree. Also, it is important to use the blue filter at all times as this gives the % light transmission of 0.

The solution into which the pigment molecules diffuse.

This is also a variable that needs to be controlled, organic solutions such as ethanol are also disruptive for the plant membrane, and therefore it is best to use a neutral kind of solution, such as water. I will use distilled water throughout the experiment so that the investigation is kept fair.
The variables that I will control are the ones listed above, the one that I am going to investigate is temperature I will increase the temperature in 5OC intervals.

Even though there is a link between my prediction and that of the data collected, it is difficult to say whether my hypothesis is correct, this can only be found out by further experimentation. Further experimentation would include repeating this experiment with the modifications suggested and a look at further factors that should affect the permeability of plant cells. One example would be to look at other plant cells apart from Beta vulgaris, or to loo at how factors such as surface area and age of Beta vulgaris affect the permeability of their cells.

The main source of error was the colorimeter itself, firstly, it was unable to remain on a constant percentage for very long. At times it would give the % transmission of water as 98 or 101%. Which shows that it had tendencies to give inaccurate results. Also I think that as many people were using the same colorimeter and spillages did take place it is possible that water went into the colorimeter which would raise an obvious source of error.

Also, as there were errors in the investigation, this is what led to anomalies, so even though the equipment used such as the stopwatch, measuring cylinders and ruler read to a good accuracy, they are still able to cause a considerable amount of error in our results.

The reliability of data and its accuracy are dependant on the apparatus used, and its accuracy. Readings were taken as accurately as possible, using the apparatus at hand. For example when using the measuring cylinder, or filling up the beakers with water, I made sure that the bottom of the meniscus touched the line marked 250ml, or 6ml.

Also, by looking at this point from several different angles, i.e. the use of parallax, to give me the most accurate measurements possible.

Also I waited until the colorimeter balanced at one particular % before writing down the reading.
The beetroot was cut against a ruler which reads to the nearest 0.5mm, also, when cutting two pieces of beetroot I cut the two pieces simultaneously so that less error would be brought to the experiment.

In these ways I tried to gain the most amount of precision from the apparatus available.
I will begin the experiment by cutting up the beetroot into 6 equal pieces. This will be done using a cork borer to ensure they are of an equal size, and the beetroot cut from the cork borer will be cut into six 2mm strips. These will then be rinsed under the tap to wash off all the excess pigment released from cutting the beetroot, so that this pigment does not affect the results. When I have all the beetroot pieces I will measure out the different solutions which they will be placed in, and set up the test tubes. The first one will be a control experiment, where the beetroot is placed in 10ml of water, with no alcohol, so that the results can be compared to this control result. I will use the measuring cylinder to measure out 10ml of water and put this in test tube 1. The next tube, 2, will have 2ml of alcohol and 8ml of water, giving it a 20% alcohol concentration. I will then measure out the solution for test tube 3, which will have 40% alcohol concentration, with 4ml alcohol and 6ml water. Test tube 4 will have 60% alcohol concentration with 6ml of alcohol and 4ml of water. Test tube 5 will have 80% concentration of alcohol with 8ml of alcohol and 2ml of water, and the final tube will have 10ml of alcohol and no water. When each of these 6 tubes have been set up, I will place a piece of beetroot in each of the tubes and begin timing using the stopwatch. I will then leave the experiment for 30 minutes.

When the 30 minutes is up, I will take the beetroot pieces out of each of the tubes, and I will then begin to measure how much pigment has come out. There are two ways in which this can be done. The first is a very subjective method, in which you give each tube an arbitrary value for the redness of the solution, with the darkest red being 10, and the lightest red being 1. The second method is more scientific and will give more accurate results to work from. Using a colorimeter I will measure the amount of light which will be transmitted through each solution. This is done by putting a sample of the solution into the colorimeter, and sending a beam of light through the solution, then reading off the value showing the amount transmitted through. The more light which transmits through, the less pigment present in the solution. After I have done the whole experiment once, I will repeat the experiment a further two times, so that I will have three sets of results. This will help to improve the validity of the results.

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