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Core practical(Why does the colour leak out of cooked beetroot?)

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Core Practical Why does the colour leak out of cooked beetroot? Introduction:- Beetroot contains red pigment called betalain, located within the cell vacuole. Normally the pigment cannot pass through membranes but they leak out when the beetroot cooked because the cell membrane begins to breakdown. Hypothesis:- My hypothesis is that when temperature increases the proteins in the membrane will be denatured and the pigment will leak out of the cell membranes and will colour the water in the test tubes. Method:- Apparatus:- a thin cylinder of beetroot tissues, nine test tubes, beaker ,Bunsen burner, water, thermometer, colorimeter. Variables:- * Independent: Time, temperature * Dependant: Intensity of red in water Procedure * We were provided with thin cylinders of beetroot tissue, which was washed in running water overnight. ...read more.


* We reduced the temperature of the water by75?C by using cold water. This method was used by reducing temperature the water to 65?C, 55?C, 45?C, 30?C, and 25?C. * Put beetroot in to the crushed ice at 15?C and allow for 20 minutes. * We measured the intensity of red in the water by using colorimeter. We filled another curette with distilled water as a control to get 100% transmission. Safety:-_ * Hot water: heating water on a Bunsen burner means great care mast be taken to avoid scalding. * Knife: when using a knife care must be taken because you might damage your self. * Do not eat beetroot because it is not clean and it is old. . ...read more.


Colour intensities could be measured more accurately by means of a more accurate colorimeter accurately. Alternatively, a semi-quantitative method may be used: for example take 1 ml solution from the most intensely coloured tube as a colour control which can matched by pouring the next less intense solution into a second tube and adjusting the volume until the colour of the two tubes match one another when viewed from the top. The height of the solution in the second typeis an indication of the relative light intensity of the solution. It is possible that physical damage done to the beetroot cells when handling them, during the transfer from one tube to another could have affected the outcome. Some more careful handling of the beetroot would be essential. Reference:- Salters-Nuffield Advanced biology. (2005) ?? ?? ?? ?? ...read more.

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3 star(s)

This is a reasonable description of the investigation but some parts of the procedure are unclear and more A level knowledge should be evident in the conclusion and explanation.

Marked by teacher Adam Roberts 29/05/2013

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