Investigate the effect of temperature on enzymes, by calculating the amount of gas produced in the reaction at different temperatures.
* Independent variable: temperature
* Dependant variable: amount of gas produced
* Variables not changed: amount of potato, pH, volume of H2O2, same time, type of potato and preparation of specimen.
Aspect 2 – Controlling variables
1. Collect necessary equipment and materials.
2. Set up apparatus for the experiment as shown.
3. Weigh 2g of minced potato using a scale up 1/100 of a gram.
4. Put the potato in the conical flask and add 5cm3 of buffer solution at 70C. Swirl gently to mix. Temperature must be stable while reaction is taking place.
5. Replace the bung in the flask, ensuring that it is at right seal.
6. Fill the burette with water and introduce into it the tube that comes from the flask bung. Invert carefully into the beaker that contains water.
7. Measure 5cm3 of hydrogen peroxide into the syringe and connect it to the flask. The H202 has to be at the same temperature as the water in the container, if the water is at 70C, the H2O2 ha to be at 70C as well.
8. Inject the H2O2. Immediately, start counting time with a stopwatch and record measures of the level of water in the burette every 30 seconds.
9. Repeat the experiment but now at 60C, 50C, 40C and 30C.
Aspect 3 – Developing a method for collection of data
* Use a suitable range of temperatures that will show how the enzymatic activity is affected by temperature.
* List of equipment and materials: minced potato, beaker bung, burette, grater, syringe, electronic scale, measuring cylinder, conical flask, kettle, plastic tube, water container, thermometer, buffer solution, H2O2, water, stopwatch.
DATA COLLECTION AND PROCESSING
Aspect 1 – Recording raw data
Aspect 2 – Processing raw data
Aspect 3 – Presenting processed data
Rate of reaction
CONCLUSION AND EVALUATION
Aspect 1 – Concluding
I can conclude that the temperature affects the enzymatic activity as expected. If the temperature it is too high, the enzymes cannot work properly, however if their environment is not warm enough, their rate of reaction is lower. In this experiment, the ideal temperature at which the enzymes work the best is around 60C, as it is shown, were the highest point in the Rate of reaction graph is at 60C. Below this temperature, the enzymes work less efficiently than they do at 60 and it can also be seen on the graph, where all temperatures higher or lower than 60C are below the highest point. Also, if the temperature is above 60C the graph shows us a decrease in the rate of reaction indicating that at that temperature, enzymes start to denaturate so their rate of reaction decreases.
So, my hypothesis has been proved. Enzymes are affected by temperature by increasing or decreasing their rate of reaction. Enzymatic activity then, has its best performance at around 60C, since at lower or higher temperatures; the rate of reaction is lower.
Aspect 2 – Evaluating procedures
As it can be seen on the graph, there is an anomaly, which is the point standing out of the other points. The factors that could have been affecting the results are that the temperature was higher than it should have been or because the H202 was not measured so accurately. The results however, are very good in general it was a good practical.
Aspect 3 – Improving investigation
There are some aspects of the experiment that could be improved to get more accurately results and to avoid anomalies such as:
* Be more accurate with preparation of specimen, with the starting mass and size of it, use a machine to cute and grate it more accurately.
* Making sure the scale is exact.
* Potato affected by oxidation. It was not used immediately so a good improvement would be to prepare specimen and use it immediately.
* Use a wider range of temperatures such as 30oC, 35 o, 40 o, 45 o, 50 o, 55 o, 60 o, 65 o, 70oC to see closer how enzymes are working.
* Repeat the experiment two or three times to get more reliable results.
* Make sure that temperature is always steady while reaction is happening.
* Try the same experiment but with a different specimen, using carrots, apples or something else instead of potatoes.