The independent variable is the different temperatures set in the water bath, to see the effect of temperature on cell membranes. The length of the cut beetroot is controlled, they each had the same surface area, and this is to ensure that the average amount of dye that will run out of each beetroot is similar. The temperature of the water after 30 minutes cannot be controlled. The cylinder size, volume of distilled water, which was 5cm3, the time in the water bath, can all be controlled. The dependent variable will be calculated by using the colorimeter to measure the absorbancy reading from each sample of the water n the cuvette.
The systematic errors could be when using the cuvette, the cuvette could be dirty or the cuvette could be scratched, the error introduced would be the same throughout the investigation. The incorrect use of equipment could cause systematic errors. By not calibrating the colorimeter before use could cause errors. Additionally reading volumes in pipettes/measuring cylinders at the top of each menicus instead of reading at the bottom could cause faulty measurements (parallax on measuring). The water bath could be slightly out, because the temperature may not be exactly on 00C, 100C, 200C, 300C, 400C, 500C, 600C and 700C.
The random errors may be reading the volumes, or not precisely measuring out the volumes. Carelessness, like not concentrating on times that is meant to use during the experiment (30 minutes). Or likewise, not taking care when measuring the temperature of substances, it could go over the temperature needed.
The only alterations I would suggest would be to repeat the experiment 2 or 3 times to get an average.
Risk Assessment
- When cutting the beetroot into 1cm sections, take care when using the knife, these may be very sharp.
- The temperature of the water will be very hot in some of the water baths; do not let it get on the skin, as this will scold the skin. Be careful not to bump into the water baths, this could spill the water, cause injury or cause people to slip and get injured.
- When transferring the liquids from different boiling tube, use tongs or heatproof mats to prevent scolding of the hands.
- Carelessness could cause the glass to break, causing an injury.
- Ensure test tubes are kept in test tube racks, and keep all glass apparatus in the middle of the worktop.
Results
Absorbancy readings
Patterns of results
The graph shows that as the temperature increases, so does the absorbancy. At the temperature 200C - 300C, there wasn’t a big difference in the average absorbancy rate. But, from 400C – 500C, there is a huge difference, where the absorbancy jumps from 0.35 to 1.13.
Conclusion
After collecting and correlating the results, I have come to the conclusion that the hypothesis is correct, in that an increase in temperature will damage and denature the membrane and cause the substances contained within the membrane to leak out. Anthocyanin is a family of pigments that give flowers, fruits and leaves of some plants their red or blue coloring. This has been shown by a steady increase in betalains which leaked out of plant cells, which was then measured by the colorimeter light absorbance, as the temperature increased. By analyzing the results, denaturing occurs between 400C - 500C.
The breakdown of the lipids which make up the membrane which causes 'holes' to appear in the membrane, allows fluids to pass out freely, but when the temperatures begins to get higher, the proteins in the cells begin to break down as well which blocks some of the holes and therefore slowing down the release of anthocyanin.
It is safe to say that the results have been repeated reliably however it still would have been beneficial to have repeated the experiment more times to make certain that the results were not gained through chance or by an external factor. Distilled water was used, which is the clearest possible liquid, meant that even the slightest deviation in colour could be detected by the colorimeter.