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beetroot experiment

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Introduction

Why does the colour leak out of cooked Beetroot? Introduction: The purpose of this experiment is to investigate the effect of temperature on membrane structure and highlight experimental and investigative skills. Background Knowledge: Beetroot appears as a dark/red purple colour caused by 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 different membranes, the membrane bounding the vacuole and membrane enclosing the cell. Beetroot cells are quite unstable and will leak out when cut, heated, cooked, or when in contact with air or sunlight. This can also be showed and done by adding detergents and solvents as part of solution with the beetroot. Beta lain pigments are named after "beet" family of plants. Plant cells are quite different from other eukaryotic kingdom's organisms. Their distinctive features are: large central vacuole that maintains the cell's turgid and controls movements of molecules' cytosol and sap, of course chloroplast that contain chlorophyll which is the pigment that allows photosynthesis and more importantly the nucleus which controls the whole activity of the cell, also a wall made up of cellulose and protein deposited by protoplast on the outside of cell membrane. The plasma membrane is the inner layer of protection surrounded by rigid cell wall. The purpose of a cell membrane is to control the transport of substances moving into and out of the cell. The cell membrane is partially permeable due to its thin layer (7-10 nanometres) thick. It consists mostly of lipids and proteins the lipids found in cell membranes are triglycerides, have one molecule of glycerol chemically linked to 3 molecules of fatty acids, the majority being phospholipids. ...read more.

Middle

Place the cuvette into the colorimeter making sure that the light is shining through smooth glides. 8. Adjust the colorimeter to read 0 absorbance for clear water. Do not alter the setting again during the experiment. 9. Place 2 cm3 of the dye solution into a colorimeter cuvette and take reading for absorbency. Repeat readings for all the temperature. 10. Present your results in appropriate way. 11. Identify any trends or patterns in your results. 12. Explain any trends or patterns supporting your statements with evidence from your data and scientific knowledge. 13. Describe how you could have improved this experiment to give more reliable results. Results: A table of results to show Average light percentage absorbency of the dye solution in responds to the temperature and time taken. Temperature/�C Bath Temperature/�C Light Absorbency/% Average light Absorbency/% Time/minutes 1 2 0 1 0.33 0.28 0.31 34:55:5 10 20 0.06 0.03 0.05 33:33:6 20 19 0.03 0.02 0.03 32:51:6 30 31 0.04 0.03 0.07 30:48:4 40 40 0.08 0.08 0.08 29:14:6 50 49 0.48 0.26 0.37 28:03:7 60 60 1.85 1.75 1.80 27:14:3 70 68 2.00 1.80 1.90 25:32:3 A GRAPH TO SHOW THE AVERAGE LIGHT ABSORBENCY IN RESPOND TO THE TEMPERATURE INDICATED. Analysis: From the graph, the overall trend seems to be that as temperature increases, the percentage absorbency of the light absorbed increases gradually although there were points in the graph that didn't lie on the line of best fit. This is suggesting that membrane permeability decreases with temperature and gradually pigment leaks out. The darker the colour means more pigments have leaked out and higher percentage of absorbency is. As expected, the hottest temperatures were the deepest colour. ...read more.

Conclusion

To prevent this from happening, one good respond is to use more sensitive equipment or to get colorimeter checked because it could be broken and will result to equipment failure and false reading. Human error can be the biggest source of error as well. Because on some occasions, we didn't shake the boiling tubes with the equal efforts before we took the beetroot out and so could have been one of the reasons why the solution is darker or lighter than it should be. On inaccuracy that can be account to human error is the size of the beetroot. This could be explained by free hand sectioning because this would affect the surface area to volume ratio which in turn affects the diffusion. If the size was slightly smaller, it would have reduced the surface area therefore decreasing the amount of pigment leaked from the sample and makes the solution normal in respond to temperature. Another reason for the anomalies appearing could be due to the preparation sample. Many of the cells could have been damaged causing the pigment to leak during the experiment. A way of overcoming the inaccuracy of the measuring equipment used is to have rulers which are graded more accurately which may help to prevent inaccuracies occurring in the future. Possible additional work that can be done to rectify errors and would make the experiment much improved than it was before and could make findings more accurate are the following: using digital thermometers which can feed information on temperature continuously to a computer system would be ideal also, the experiment should be repeated more than two or three times and by doing so, it would be easier for me to work out clear average from wide numbers of range values in between results. ...read more.

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