NB: this is an ‘outline method’ intended to ensure that reasonably consistent and useful results are obtained. However, some instructions are deliberately vague (these are underlined): you are expected to adapt the method as you go along: to clarify details that were omitted, take sensible precautions, and work around any problems you encounter. Outline RQ: “How does temperature affect the amount of dye released from beetroot cubes?” Hypothesis & brief explanation: “Up to a critical temperature, there will be little release of dye. Above this, there will be a sudden increase in dye release, until all has been released and a plateau is reached. Because beetroots grow from around 5-25°C, there is no cause for a release of dye at these temperatures. Above this, heat will damage the cell membranes and release the dye.”
Take a slice, approx 5mm thick, from the beetroot provided. Cut off and discard the skin. 2.
Use the remainder of the slice to cut a supply of at least 50 small cubes (approx 5x5x5mm). Hint: this step can be done ‘by eye’, as long as your cubes are all about the same size. 3.
Place the cubes in the sieve, and leave them to rinse under cold running water for at least 3 minutes, while you perform steps 4 and 5.
Using a permanent marker, label 5 test-tubes with your initials and the 5 most appropriate temperatures from the range available. 5.
Pippette 5cm3 of deionised water into each of the tubes. Place each tube in the appropriate temperature, to equilibrate. 6.
If no further colour is released from the cubes in cold water, rinsing is complete. Start your stop-clock, and immediately place a suitable sample of cubes in one of the tubes. Hint: you may wish to practise this with a spare tube to define a suitable sample. 7.
Set up each of the remaining tubes with a sample of beetroot cubes at one-minute intervals. 8.
Leave each tube to incubate for 20 minutes.
NB: the fluid inside each tube should not be higher than the level of the...
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