Results
Tube treatment of liver height of froth (cm)
A raw solid cube 10.5cm
B boiled solid cube 11cm
C boiled ground paste 9.5cm
D raw ground paste 10.4cm
Conclusion
A firm conclusion is not applicable to this experiment.
Cells can break down hydrogen peroxide because hydrogen peroxide is poisonous and is a product when the liver breaks down waste therefore enzymes (catalase) must be made in order to deal with it.
When the enzyme catalase is added to hydrogen peroxide, oxygen gas is given off.
Liver can be proven that it contains catalase with the following pieces of evidence: A) the height of the froth differs to what treatment it is given, the un-boiled liver has a higher level of froth which means the boiled liver has some catalase destroyed due to the heat. B)There would be no reaction if catalase wasn’t present.
The height of the froth in test tubes A and D is more or less the same with the raw solid cube having a slightly higher level of 10.5cm whereas the paste has 10.4cm. This suggests that the surface area has no affect on the catalase although the boiled results suggest otherwise.
To collect the gas and measure the volume of the gas accurately you would use a delivery tube. You could test the oxygen collect a sample of the gas and place a glowing splint in the gas - it should relight.
If drops of acid were added to tube D then I would expect the acid would denature the enzymes further. If tube C was to be kept at 35c rather than room temperature 20c I would expect the increased temp to denature the enzymes further.
Evaluation
Experimental errors:
The accuracy of the experiment is poor for a number of reasons.
Boiling for 2 minutes was not enough to denature the enzymes.
Make sure to denature enzymes a series of experiments to gain adequate results.
Liver is hard to grind use sand to aid in the liver grinding.
The test tube diameter varies which in turn cause faulty results when froth bubbles obtain test tubes with same diameter.
Froth constantly changing measure froth at the exact same time.
Cubes different sizes – surface area is very different on each cube also are roughly weighed not all exactly 5g measure weight to exactly 5g. Use food processor to convert cubes to paste in doing this you will have the same surface area.
The reliability of the evidence:
The evidence in this experiment is not very reliable e.g. not having the same size cube can make a lot of difference to the experiment, the test tube diameter being different widths will dramatically affect the height of the froth which will make the results faulty.
The boiled liver results are anomalous because there should be no froth as all the enzymes are supposed to be denatured, obviously boiling for 2min is not enough.
Extension material (more experiments):
-Firm conclusion was not possible in this experiment.
-Series of experiments to gain adequate conclusion.
-Boiling for 2 minutes was not enough to denature the enzymes.
-Make sure to denature enzymes – a series of experiments to find at what temperature the enzymes become de-natured.
Experiments for both of the above could prove useful in gaining an adequate conclusion and a more accurate set of results.