Procedure:
- Set up the device for measuring the pressure
- Assemble it
- Plug it into the computer and open Logger Pro 3
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Set up an “experiment” in the program for 60 seconds, data taken every second
- Cut 12 pieces of liver
- 3 pieces of liver with the mass of 1g, 1.5g, 2g and 2.5g
- Put a piece of liver into the pyramid-like tube
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Load the syringe with 15 mL of hydrogen peroxide
- Press “start experiment” in LogoPro and pour the hydrogen peroxide into the nalgene reaction bottle and cover it with the device measuring pressure
- Wait until the computer program finishes recording data
- Save the data on the computer
- Clean the tube
- Repeat steps 3-8 with all of the liver pieces
Safety gear:
Data Collection and Processing
Graph #1. 1g cow liver pieces
X-axis – time (s). Y-axis – pressure (kPa)
In every trial, there was a drop in the beginning, followed by a steady raise in pressure. Trial #2 and #3 were very similar, even though #3 had a bigger drop in pressure in the beginning. Average ending pressure was 92.61 kPa.
Graph #2. 1.5g liver pieces
X-axis – time (s). Y-axis – pressure (kPa)
This time only the first trial had a drop in the beginning. The other two had a rapid increase in the beginning, with a smoother raise in pressure towards the end. The average ending pressure was 95.57.
Graph #3. 2g liver pieces
X-axis – time (s). Y-axis – pressure (kPa)
This data showed a great variety. All three trials are completely different from each other. During trial #3 the pressure reached was above 105 kPa. The average result though was 95.97 kPa.
Graph #4. 2.5g liver pieces
X-axis – time (s). Y-axis – pressure (kPa)
Trials #1 and #2 had a similar ending pressure, but the raise in pressure was different over time. Trial #3 was quite lower than the two before. The average ending pressure was 102.17 kPa.
Possible Errors:
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In some of the trials, when pouring the hydrogen peroxide (H2O2) into the nalgene bottle and taking the syringe out, there was a pressure drop. It was caused by not closing the hole, through which H2O2 was poured, before taking the syringe out.
- Liver pieces were not similar enough in shape. Some were thinner and longer, while other were thicker and shorter, resulting in different surface areas and therefore uncertainty in data.
- The measuring device was not of 100% precision and accuracy. It sometimes recorded the same amount of pressure for 2-4 seconds, and the starting pressure was not always the same.
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The speed of pouring in the H2O2 was not the same, resulting into some data having large spikes in the beginning of the trial
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Timing between trials of starting recording and pouring in the H2O2 was not same. This could have affected the data received, because the trials had different reaction times
Conclusion
A raise in pressure and difference in data between treatments proves that this method is viable and can be used for such types of experiments. The data suggests that an increase in surface area results in greater enzymatic activity. However, the amount of errors prevented a solid confirmation. These errors introduced uncertainties, which greatly affected the data.