The document describes a student's lab experiment investigating the effect of temperature on the activity of the enzyme catalase. Catalase breaks down hydrogen peroxide and was tested at four temperatures (3°C, 25°C, 45°C, and 60°C) using chicken liver. The student measured gas pressure over time for each trial and found that the enzyme worked best at 45°C based on the peak average pressure. Limitations included a lack of time, materials, and temperatures tested to draw stronger conclusions.

1. Tang Chairatana
IB Biology SL
Period 8
Catalyze Lab
Defining the Problem and Selecting Variables
In this investigation, catalyze, which is an enzyme that breakdowns chemical reaction in human
bodies, is being investigated. Temperature is the area being tested with the catalyze enzyme,
which is, in this case the chicken liver. In this lab, equal amount of chicken liver is being added
to the same amount of 3% H2O2 solution that was set in four different temperatures (3°C, 25°C,
45°C, and 60°C). This is the test to see which temperature will the catalyze enzyme works best
at. The prediction would be that the enzyme reaction will work best at 45°C.
Controlling Variables
Concentration of substrate: same % of H2O2 solution was added to the same % of chicken liver or
the ratio of 1:1. In this case, 5 ml of chicken liver is added to 5 ml of H2O2 solution.
Ph level: By having the same amount of the two solutions, the pH level is the same
Concentration of enzyme: same % of chicken liver was added to the same % of H2O2 solution or
the ratio of 1:1. In this case, 5 ml of chicken liver is added to 5 ml of H2O2 solution.
Volume of Container: test tubes have to be the same size every trial and test. In this lab, open-
mouth test tubes are being used.
Describing a Method for Collection of Data
1. Set up 12 test tubes in one test tube rack for 4 racks. In each test tube rack, 6 of the test
tubes will be for the solution and another half will be for the enzyme. So be sure to know
which on is for which. Each rack will be at different temperatures.
2. Pour 3% H2O2 solution into a 250 ml beaker. Just enough to fulfill all 24 test tubes.
3. Pour the chicken liver that has been grinded into a 250 ml beaker. Just about 1/8 of the
beaker. Then added water to the beaker just enough to fulfill the rest of the 24 test tubes.
Remembered to stir the chicken liver and the water till they mixed together well.
4. Used a pipette to measure the amount of solution and the enzyme so they are the same. In
this case, an equal amount of both is 5 ml. The solution and the enzyme are being added
to different test tubes that have been set up in the beginning.

2. 5. Set up a computer to logger pro and attach the gas pressure sensor lab to it in order to
measure the gas pressure of the enzyme that will react in different temperatures.
Temperature Observations 6. After all the set up, put each of the
(°C) test tube rack that contained both 6
test tubes of 5 ml of the 3% H2O2
25(°C) Yellow, green color after solution and 6 test tubes of 5 ml of
mixing with little bubble the chicken liver in different
45(°C) The color of the mixing temperatures which are in this case,
solution was white and lots 3°C, 25°C, 45°C, and 60°C.
of bubble 7. Leave the test tubes in different
3(°C) Little bubble temperatures for 30 minutes.
60(°C) White with some bubbles 8. After 30 minutes, check the
temperature inside and outside of the
test tubes with the thermometer in order to see whether the temperatures were the same or
not. If not, wait a little more, then measured again. If yes, continued with the procedure.
9. Pour one of the chicken livers into one of the test tubes that contained the H2O2 solution.
Put the gas pressure sensor lab on top of the test tube and click ‘collect’ in logger pro.
This should be done within the temperature itself which means that do not take the test
tube racks out of the water when measure.
10. Did it for every test tube in every temperature, record data and save the graph on logger
pro
Temperature Trial 1 (kPa/ Trial 2 (kPa/ Trial 3 (kPa/ Trial 4 (kPa/ Trial 5 (kPa/
(°C) s) ±0.01 s) ±0.01 s) ±0.01 s) ±0.01 s) ±0.01
25(°C) 21.57 12.99 17.52 23.56 25.45
45(°C) 37.53 29.83 44.08 59.85 35.03
3(°C) 0.63 0.46 0.23 0.45 0.06
60(°C) 2.82 1.41 4.08 1.22 1.68
11. Used only five trails of each temperature to make the table. To have six trials is just to
have spares because one might be messed up.
Recording Raw Data
Table 1: Quantitative raw data of the enzyme reactions in different temperatures
Table 2: Qualitative raw data of the enzyme reactions in different temperatures

3. Processing Raw Data
Table 3: The average of the measurements of the enzyme reaction to different temperatures
Temperatur Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
e (°C) (kPa/s) (kPa/s) (kPa/s) (kPa/s) (kPa/s) (kPa/s)
±0.01 ±0.01 ±0.01 ±0.01 ±0.01 ±0.01
25(°C) 21.57 12.99 17.52 23.56 25.45 20.22
45(°C) 37.53 29.83 44.08 59.85 35.03 41.26
3(°C) 0.63 0.46 0.23 0.45 0.06 0.37
60(°C) 2.82 1.41 4.08 1.22 1.68 2.24
Sample Calculations:
• Average
o 45°C
 (37.53 + 29.83 + 44.08 + 59.85 + 35.03 + 41.26) / 5 = 41.26
Presenting Processed Data
Graph 1: Trail 4 of an enzyme reaction VS. 25 °C temperature

4. Graph 2: Trial 4 of an enzyme reaction VS. 45 °C temperature
Graph 3: Trial 3 of an enzyme reaction VS. 3 °C temperature
Graph 4: Trial 4 of an enzyme reaction VS. 60 °C temperature

5. Graph 5: Average kPa/s of an Enzyme reaction to four different temperatures
Caption: at 45 °C is the maximum point that an enzyme will work best at and lower than that
will cause the enzyme to denature or stop working.
Concluding
Through the investigation, the conclusion of this lab was that according to graph 5 above, the
enzyme worked best at 45 °C and the other temperatures were causing the enzyme to be
denatured or slowing down till it stopped working. This also supported the prediction that the
enzyme will work best at 45 °C because that was where the graph peaked.
Evaluating Procedure

6. There are several weaknesses of this lab. The biggest concern in this lab was time. There was not
enough time to do the lab. There should be more data in order to get accurate results. Also, the
materials in this lab were not enough for everybody because one person if he or she was doing
temperature has to use 48 test tubes at a time to complete the lab and there were like 13 students
doing a lab at once. Moreover, having more temperatures to work on would have had more data
to compare and see the results. Furthermore, 3% H2O2 solution was too strong to work with
because closing the test tubes with the stoppers; they just popped out because the reactions were
really fast.
Improving the Investigation
To improve this lab, 3-4 hours are needed to complete this lab because in order to collect more
trails of each temperature, lots of time is needed. Also, lots of materials should be prepared,
especially test tubes, to complete this lab because one person is going to need a lot to complete
the lab in a given amount of time. Additionally, at least five temperatures should be worked on in
order to see easier comparison among them. Moreover, only 1.5% of H2O2 solution is suggested
using because greater percentage than this would make the reaction goes too fast.