Investigating Cellular Reactions

Investigating the effect of different environmental factors on the reaction of liver and hydrogen peroxide

Table of Contents

1 Design 3
1.1 Variables 3
1.2 Safety and Environment 3
2 Data Collection and Analysis 3
2.1 Collected Raw Data 3
2.2 Qualitative data 5
2.3 Processed Data 5
2.4 Graph on test tube 2 5
2.5 Graph on test tube 3 6
2.6 Errors 6
3. Conclusion and Evaluation 6
3.1. Conclusion 6
3.2. Evaluation 7
3.2.1. Random Errors 7
3.2.2. Systematic Errors 7
3.3. Improvements 7
1 Design

Look to sheet titled: 'Investigating the action of the enzyme catalase'

1 1.1 Variables

The independent variables are the acids used, the dependant variables the height of the bubbles formed and the control variables the test
tubes used.

2 1.2 Safety and Environment

The safety and environmental precautions for this lab are quite strict.
Wear safety goggles and a lab coat to avoid getting any acid on your person, and dispose of the acids in a sink with plenty of water. Collect the used liver samples and dispose of accordingly.

2 Data Collection and Analysis

1 2.1 Collected Raw Data

|Test tube |Height of bubbles (cm) | |
| | |pH |
| |30s |

|30s |60s |90s |120s |150s |180s |210s |240s |270s |300s | |1 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 | |2 |12,9 |13 |14,1 |13,3 |11,7 |10,4 |9,3 |6,7 |5,5 |5 | |3 |14,2 |10,8 |8,4 |6,9 |5,5 |7,5 |3,3 |3 |2,8 |2,7 | |4 |1,9 |1,9 |1,8 |1,4 |1,3 |1,3 |0,4 |0,2 |0,1 |0,1 | |5 |0,2 |0,2 |0,2 |0,1 |0,1 |0,1 |0,1 |0,1 |0,1 |0,1 | |6 |0,5 |0,6 |0,9 |1 |1,4 |1,6 |1,8 |2 |1,3 |1,4 | |

2 2.4 Graph on test tube 2

3

4 2.5 Graph on test tube
3

As can be seen from the two above graphs, test tube 3, which had the exact same conditions as test tueb 2 except for the surface area of the liver, had a much more vigourous reaction, due to the increased surface area of the crushed liver.

2.6 Errors

The only piece of equipment that is to be considered in error calculations is the ruler used which had an uncertainty of approx. ±0,2 cm.

3. Conclusion and Evaluation

3.1. Conclusion

The experiment was meant to create an artificial catalase reaction between the enzymes in the liver sample and hydrogen peroxide. The sample in test tube 2 reacted with the hydrogen peroxide and produced oxygen bubbles at a somewhat steady pace, while the sample in test tube 3 reacted vigorously at first and then slowed down as most of the enzyme had been used up.

3.2. Evaluation

3.2.1. Random Errors

The liver was quite hard to get into perfect ½cm3 cubes, as it tended to get squished when the knife was pressed down, making the sample larger lengthwise, but smaller height-wise. Also when the reaction was very rigorous, the oxygen bubbles sometimes lifted the liver out of the hydrogen peroxide, causing it to stop reacting with the hydrogen peroxide. While not a major issue, sometimes the time at which the results were checked were not exactly at the designated 30 second intervals, due to many things going on at once.

3.2.2. Systematic Errors

The ruler we were using was quite old and dirty, with some of the finer millimeter markings rubbed off or obscured, leading to readings that were not as accurate as they could have been. The molarity of the chemicals used can also be put into question.

3.3. Improvements

The liver could be frozen or in some other way petrified to make the cutting easier and more precise. The liver should be checked constantly and adjusted back down with a glass rod if necessary. Enough time should be allocated to ensure that the experiment can be done in a calm and orderly fashion to avoid any oversights in the time taking. Clean and clear rulers should be used to measure the bubbles. The molarity of the chemicals should be checked with titration or some other form of double checking the molarity.