Why does the colour leak out of beetroot? Procedure to investigate the effect of temperature Hypothesis- The higher the temperature while cooking the beetroot, the more pigments well leak out from the cell membrane, hence the absorbance would increase. My hypothesis was concluded by the facts that beetroot contains red pigments called betalians which are located in the cell vacuole. Normally the pigments cannot leak out; however cooking the beetroot allows the movement. This is because the cell membrane selectively controls the movement of substances into and out of the cell.The membrane is made of 40% lipids, 0-10% carbohydrate and 50- 60% protein. Lipids tend to liquefy at high temperatures causing ruptures in the plasma membrane.
This means when beetroot is cooked the cell membrane will liquefy; therefore my hypothesis is the higher the temperature the more pigments will leak out. Equipment used: Beetroot Cork borer White tile Knife Ruler Water baths (temperatures ranging from OOC to 700C with 1 OOC intervals) Crushed Ice Plastic beaker 250 cm3 8 boiling tubes 2 boiling tube racks Thermometer (one for each water baths) Colorimeter Cuvettes StopcocksDistilled Water Pipettes Small measuring cylinder Independent variable: Temperature (oc) – this will be controlled by the water baths and each water bath will have a thermometer placed inside. The temperature will range from OOC to 700C and will go up in 10. Dependent variable: % of Absorbance- the absorbance will be measured by the colorimeter which will have 2cm3 of the dye solution to make it a fair test. Control variable: Length of beetroot used- Controlled by cutting each of the beetroot pieces to 1 cm and using a cork borer so that the diameter will be the same.
Amount of water-Controlled by adding 5cm3 of distilled water, measured by a pipette, into each of the test tubes. Time in the water baths – Controlled by using a stop clock to measure the amount of time. Amount of dye solution put into the colorimeter- Controlled by measuring 2 cm3 of solution using a pipette Risk assessment Hazard Likelihood (1-5) Severity Risk LXS (1-25) Control Measures Stains from beetroot 3 Wear lab coats, gloves and goggles Knife- cuts 2 6 Cut away from the body and cut on the white tile Glassware can break Handle glass equipment with care. If it breaks notify staff.
erson must compulsory stay with the broken glass while another notifies the staff. Put the broken glass into the white glass bin. Hot and cold water baths 4 Be careful when putting the test tubes in and when taking them out.
Tripping over in classroom Stools must be tucked away so that someone does not trip over. Belonging must be under the desks and Jackets/ Jumpers hung on the pegs. Accidents caused by minor things No eating or drinking Hair must be tied back Must be alert and standing while doing the experiment. Likelihood- Is the chance of the hazard occurring.
Rating from 1 to 5, 5 being the highest Severity- how sever the damaged done by the hazard can be. Rating from 1 to 5, 5 being the highest. Risk- Likelihood x Severity, can range from 1 to 25.
25 is the highest *Note any of the risks was higher than 10 the experiment would not be carried out in school. The wellbeing of the class environment and living organisms has been taken into account. That is why the experiment has little risk and none of the hazards have a risk above 10. There are also no ethical issues that can arise from this experiment.
Raw Results Temperature (oc) Absorbency (%) 0. 09 10 0. 0 20 0. 19 0. 29 0. 27 50 0.
48 0. 93 70 1. 49 Collective Results from class: Temperature of water ( ???C) Absorbance (%) Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 0. 24 0.
12 0. 28 0. 11 0. 14 0. 83 0. 22 1. 16 0.
13 0. 16 0. 31 0. 76 0.
18 0. 88 2. 0 1 . 65 0.
78 1. 33 1. 57 2. 00 Three best trials- Results: Average of the three trials (2d.
p) 0. 51 1. 12 1. 69 Trends and Conclusion: The graph has a positive collation. From the graph I can deduct that as the temperature increases; the percentage of absorbance also increases. This trend is rue for most of the differences, expect for 200C and 300C.
The averages for these two temperatures are the same. From OOC to 400C the increase in absorbance is low however after that there is a sudden increase. Furthermore the increase from 500C to 600C is a Just a bit more than double (0. 5% to about 1. 15%), and this again happens from 600C to 700C.
The reason behind the slow increase in absorbance till 400C and then the sudden increase after 400C is due to the properties of the cell membrane and the kinetic energy. During temperatures up to 400C the cell membrane is not ffected much because cells are capable of functioning well with temperatures that high.Therefore the cell membrane is not so weak that the pigments pass out. However after 400C the lipids gain a lot of kinetic energy and start to become more fluid like and allow more movement. This affects the permeability of the cell which may allow the pigments to pass out. Also the proteins that make the cell wall start to denature.
This damages the cell membrane and the leakage of pigments increases at a quicker pace after 400C. This is because the two main components of the cell embrane change properties. The results therefore prove my hypothesis right up to a high extent.
My prediction that the absorbance would increase as the temperature increases was right. However I had thought that the results on the graph would take a more liner shape. I was not aware that the increase would be slow at the start and then after 400C it would increase by nearly doubling. Evaluation Validly/ Limitations/ Improvements Results- The results that I gathered were not very precise. I know this as the even though the control measures were kept the same, the results were not accurate as I educted them from the best three trials in the class.As different people had done the experiment it did not give precise or accurate results. There were also many anomalies in the results.
Trial 2 and 3 had the most anomalies therefore I have not used those results. This might have come because the water baths were not always exactly the temperature we wanted, but rather it was +- by 2 degrees. The limitation of the results is that we do not know what would happen to the absorbance if the temperature when above 700C. It can be predicted by extending the line of best fit however we can not be sure.The results can be improved by increasing the temperature by 50C each time rather than 100C. This would have made the results more accurate. Method- The method used to prove the hypothesis was a valid method.
This is because it is repeatable. The accuracy of the method is good because the control measures are kept tightly firm and they are monitored for example thermometers are kept inside the water baths. The method is also quite precise as we have tried to keep it as fair as possible. The method limited the results in the since that we do not know for sure what would happen above 700C.
This happened because of the changes in the method. The change of leaving the test tubes with the beetroot in the water baths for 20 minutes instead of 30 minutes may not have made a big difference but then not repeating the experience in the small individual groups would have made the most difference. The time constrain didn’t allow for the experiment to be repeated. This would have made a difference on the results. To make the experiment better I think each group should have done all 5 trials and chose the best 3 from their own experiment.
This is because getting a collective esult from the class does not make it a fair test as people may Judge things such as the temperature on the thermometer or the meniscus on the pipette differently to others. Furthermore having proper stable test tube racks inside the water baths would have helped. On one of the trials the test tubes from the 200C water bath all fell into the water. This not only delayed the experiment but caused everyone an inconvenience as they had to do that part of the experiment again.
Digital thermometers inside the water baths would also be useful as it would reduce the chance of human error.Systematic Errors: Cutting the beetroot into exactly 1 cm. as the beetroot was wet and quite slippery it was difficult to cut up pieces of lcm. Measuring the temperature- as people can read it wrong and they could be + or – by h degree. Other human errors such as reading the colorimeter could have happened.
Random errors: One piece of the beetroot may have more red pigments than another. This is beyond out control but it could affect the results. The water baths were not exactly the right temperature. For example the OOC water bath was actually 30C when we carried the experiment. out