An investigation into the effects of temperature on membrane structure

-fixed variables

1. size of the beetroot
2. amount of water used with beetroot
3. the same beetroot would be used to obtain the strips
4. Surface Area of the Beetroot

These variables are fixed variables which would not change during the investigation to ensure accuracy and realiablity of the results

-the independent variable

1. the temperature of the water

The independent variable would be the variable I’d have no control over as it is essential for the accuracy of the investigation.

As the investigation is ongoing the temperature of the different amounts of water should remain the same and kept at a constant temperature which would then support my hypothesis.

 

The dependant variable:

The dependant variable in this investigation is the variable in which I’d depend on to support my hypothesis the variable we’d consider in this investigation would be

• the percentage (%) absorbance of the water

The percentage abundance of the water is what we’d be able to determine whether or not hypothesis was correct.

Apparatus list:

• raw beetroot
• size 4 borer
• white tile
• scalpel
• ruler
• water baths : control(room temp) 70,50,25,8°C,
• 4 test tubes
• 4 test tube racks
• Colorimeter
• 4 Cuvettes
• Stop clock
• Distilled water
• Pipette
• Measuring cylinder
• A roll of tissue

Safety:

• Refrain from spilling beetroot juice onto skin or clothing as it will stain with potential difficult washing out.
• toying with scalpels are extremely dangerous care should be taken and    

     Awareness of individuals if working in a crowded environment

• great care should be taken when placing test tubes into water baths as high    

     Temperatures can induce burns on skin

- Care should be taking when using a cork borer.

 Method:

1.  Cut sections from a single beetroot using a size 4 borer. Cut four, 1cm length slices from these sections using the scalpel/knife to make sure each strip is exactly 1cm.

2.  Wash slices under a tap to remove excess dye from beetroot.

3. Using the roll of tissue dry the beetroot carefully to make sure the beetroot isn’t crushed during the process.

4. put a test tube rack into each of the four temperatures

5. now place each of the four strips of beetroot into the four test tubes each containing 5cm³ distilled water into the four test tube racks inside the water baths of control,70°C,50°C,25°C and 8°C

6. Using the stopwatch time 30 minutes after the test tubes have been placed into the test tube racks inside the water baths.

7. After 30 minutes remove the beetroot sections and shake the solution formed in each of the four test tubes to disperse the dye.

8. Switch on the colorimeter and set it to read percentage (%) absorbance

9. now set the filter dial to the blue/green filter

10. Accurately using the pipette measure 2 cm³ of distilled water into a cuvette. Place cuvette into the colorimeter, making sure that the light is shining through the smooth sides.

11. Adjust the colorimeter to read 100% for clear water remove the cuvette with clear water. Do not adjust or change the settings of the colorimeter

12.  Using the pipette place 2 cm³ of the dye solution of your first temperature in a cuvette and then into the colorimeter and take a reading for the absorbency.

13.  Pour out the solution in the cuvette and repeat step 12 for all four other temperatures  

Results:

Temperature:

These are the temperature of each of the water baths.

Absorbency:

These display the amount of light that was able to pass through the Cuvette in percentage

Opaqueness (%)

This suggests how “dense” the solution was and so how thick the dye coloured the solution which would mean a lower percentage of absorbency a higher the percentage of opaqueness

From the table we see that the higher temperatures had the lowest percentage absorbency which means that the dye that where in the beetroot strips would have leaked into the water at a faster rate which would colour the water and these solutions would have a greater thickness than the other temperatures.

The results gathered that shows that lower temperatures had a higher percentage absorbency meaning not as much of the beetroots pigment (or dye) would have leaked into the water because of the lower temperatures resulting in higher percentage absorbency.

Conclusion:

From the results gathered it is safe to say that my hypothesis was correct and that as the temperature surrounding that beetroot increased the rate at which the dye leaked out of the beetroot also increased.

Evaluation:

-The investigation yielded reasonable results there where no anomalies however the method used was different from the original method. Considering I was not aware of the size of borer and at one point I used a different borer for the 50°C which affected the reliability of my results and answers why the 50°C and 70°C Percentage absorbency are very close.

In the original procedure we where told to leave the beetroot overnight to wash off excess dye however our method was different as we did not leave the beetroot overnight but washed it and tested it straight away. Considering we didn’t wash the beetroot overnight it may or may not affect the overall outcome of results.

Also with regards to the apparatus when using the Cuvette we only used one throughout the duration of the practical. This would mean it would contain previous traces of the dye solution at different temperatures which then would cause and error associated with my results. By either washing the cuvettes with distilled water or using different

The beetroot strips where washed under tap water instead of distilled water and each of the strips where washed at different times which would mean one strip may have been washed the water for a longer period of time than the other strips which again would affected the overall reliability of my results.

In the original procedure we where told to use eight strips of beetroot however in this investigation we only used four likewise we where told to use eight water baths again we used four. However it didn’t affect the results of the experiment as we could see a correlation between the temperatures and the percentage absorbency.

Also we are unaware of the age of the beetroot whether if the beetroot where fresh or have kept out of soil for a long time. The amount of dye a beetroot may contain may different with “age” fresh beetroot may contain a larger amount of dye than beetroot that may have been out of soil for along period of time.

If I where to redo the experiment, I’d have to consider using the same size borer as it would affect the overall result of the investigation therefore making my results fairer and more accurate. Perhaps sticking to the original procedure and leaving the beetroot to dry overnight to see if there would any potential differences to this investigation.

Bibblography

http://wikipedia.org                                                         Cell membrane,  2007