Equipment needed:
Procedure:
Safety: goggles must be worn during the whole process
1, cut the beetroot up in to 1x1cm cubes using the razor blade and the ruler on the whit tile (need at least 15 cubes).
2, put each piece in to one test tube and label the tubes No.1 to No.15
3, use the cylinder to measure 50ml of distilled water and put the thermometer in
4, heat the water to 40ºC then pour into the cylinder to measure 5ml quickly pour in test tube No.1
5, start the stop watch and wait for 1 minute
6, gently pour a sample of the liquid in the colorimeter cuvette and measure the colour intensity.
(using the colorimeter: Switch on the instrument for at least 5 minutes before use.Place the reagent blank solution or water in the curvette and zero the instrument. To avoid impurities that might affect a colour reading, we must only touch the non-clear side when handling it and make sure the clear sides are in the light path when it is inside the instrument. The aperture used must stay the same.)
7,write down the results of the colorimeter in the table prepared before
8, heat the water temperature up another 10 ºC and repeat process for 50ºC, 60ºC, 70ºC, and 80ºC . each temperature must have 3 or more results to insure the accuracy.
Data collection:
Size of the piece of beetroot 1cm cube
Amount of water 5ml
Time the beetroot is in the water 1min
Precautions:
If the beetroot is in the air too long then the surface may dry out and effect our experiment results. So the beetroot must not be exposed in the air for too long.
Experiment results:
Size of the piece of beetroot 1cm cube
Amount of water 5ml
Time the beetroot is in the water 1min
Two ambiguous results (*) found during the experiment:
50 ºC experiment No.2 -0.52
80 ºC experiment No.1 -0.42
The results of repeat experiment 50 ºC and80 ºC
Reasons that might have caused the ambiguous results:
The time the water heated up the beetroot might have been mistaken
The amount of water put in to the test tubes been too much.
Final results:
Graph :
Conclusion
My results show that as the temperature increases the colour intensity increases too. But the graph also shows that after 70 degrees the colour intensity starts to “slow down”, this is because there is a limited amount of substance in a cell, so that the influence of temperature on membrane stability is not unlimited. Therefore I accept m hypothesis and reject my null hypothesis.
The membrane becomes more permeable at higher temperatures. This is explained by the fact of the structure of plasma membranes that is composed of phospholipids bailer and protein. With high temperatures, the proteins denature and the phospholipids structure changes, and becomes less stable.
Beetroot cells are eukaryotic cells and have many types of cell organelle present. Some of these organelles are bounded by a single membrane, such as lysosomes, Golgi apparatus, vacuoles; some are bounded by two membranes (an envelope), e.g. nucleus, mitochondrion. Beetroot appears as a dark red or purple colour becaused of the betalain pigment, which is contained within the vacuole of beetroot cells. In order for the betalain to leave the cell it needs to pass through 2 different membranes: the membrane bounding the vacuole and the membrane enclosing the cell. A biological membrane is made of a phospholipid bilayer. These are formed because the phospholipids that make it up have a polar "water-loving" hydrophyllic head and a “water-hating” hydrophobic tail. The tails pack together, exposing only the polar heads to the water. In a cell they form sacks. One goes all around the cell (the plasma membrane), others may form vacuoles. Yet others may be like stacks of half empty bags.
In physics we know when you heat the temperature of something you give it energy, in this case the molecules start to spin and vibrate faster, the water will expand too. This will have a disruptive effect on any membrane in its way. Not to mention the lipids become more fluid as temperature goes up, so the membranes become more fragile.
Proteins are formed of coiled and folded strings of amino-acids, held together by hydrogen bonds and disulphide bridges. If you heat them too much, they will untangle and break apart, mostly caused by the vibration of molecules. When this happens to the proteins spanning a lipid membrane, they will form holes that will destroy the structure, making pigments even in the innermost compartment to spill out.
Evaluation
The equipment for the experiment is limited. The thermometer may not always be accurate; sometimes the thermometer may be slightly higher or lower than the real temperature. This will interfere with the results by influencing the beetroot membrane to become more or less permeable than it is supposed to and making the colour intensity to not be accurate. It’s effect on the results can not be Predicted. But we used the same thermometer throughout the experiment therefore it will not influence the final conclusion. This problem may be solved by using a more reliable digital thermometer or by using two or more thermometers at once and taking the average temperature.
The piece of beetroot is crucial to the experiment results. The beetroot pieces of beetroot can’t be guaranteed to have the same quality. Some pieces of beetroot may not have the same amount of water in them due to their growth, this will make the beetroot colour intensity higher or lower than the other pieces of beetroot would have been. They may not have the same freshness to influence the results. Its influence on my data would depend on the quality of the beetroot, if it is fresh and juicy, colour could be darker than a dry, old piece of beetroot, this can only be observed at the time of experiment. To prevent this from influencing the final result, the quality of unusual pieces of beetroot should be noted down during the experiment, and used to explain if the result is higher or lower than it should be. To avoid in-accurate results it would have been best to use beetroot samples from the same beetroot and not take the bits that have been exposed in the air for a long time.
The deficiency of my experiment is the narrow range of temperatures; I should have done the experiments of 90 and 100 degrees to prove that the influence of temperature is not unlimited.
