16 Which Type Of Cell Is An Animal Cell Biology Experiments for Teachers – Enzymes: Catalase

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Biology Experiments for Teachers – Enzymes: Catalase

Security. Although the risks involved in the following experiments are negligible, you are advised to consult the latest publication of ‘Safeties in the School Laboratory’ published by the Association for Science Education (ase.org.uk ) before performing any test.

Line. Catalase is an enzyme that occurs in the cells of many organisms. Some energy-releasing reactions in the cell produce hydrogen peroxide as a by-product. This compound, which is toxic to the cell, is split into water and oxygen by the action of catalase. 2H2O2 = 2H2O + O2

Samples of liver and yeast are immersed in hydrogen peroxide. Oxygen is developed and the student is asked to extend the experiment to try and determine if the enzyme in the tissues is responsible. Tests and questions take about an hour.

Prior knowledge. The existence of inorganic catalysts; enzymes denatured on boiling; Oxygen relights a glowing splint.

Advance preparation and materials – per group

20 volumes of hydrogen peroxide 50 cm3


liver, about 1 cm cube

distilled water 20 cm3

dry yeast about 1 g

clean sand about 1 g

activated charcoal granules, about 1 g

Application – per group

test-tube rack and 4 test-tubes

force or search for pushing the liver into the test tube

4 symbols or spiritual symbols

funnel filter

Bunsen burner

paper filter

test-tube holder

mortar and pestle


The study below is a critical examination of plant and animal tissues to see if

they contain catalase.

(a) Label three-tube test 1-3.

(b) Pour about 20 mm (deep) hydrogen peroxide into each tube.

(c) Cut the liver into three pieces.

(d) To tube 1 add a small amount of liver, and to tube 2 add a pinch of dry yeast.

(e) Insert a smooth splint into tubes 1 and 2, bringing it close to the surface of the water or into the upper part of the froth.

1 Describe what you see happening and the effect on the smooth spleen.

2 How do you interpret these observations?

3 Is there any evidence from this experiment so far, to show whether the gas is coming from the hydrogen peroxide or from the solid?

4 Is there any evidence at this stage that an enzyme is involved in the production of gas in this reaction?

(f) In tube 3 place some granules of charcoal and observe the reaction.

5 Can charcoal be an enzyme? Explain your answer.

6 Assuming (i) that the gas in (f) is the same as before and (ii) that the coal is almost pure carbon, does the result with coal help you decide on the source of the gas in this and the previous experiments?

(g) Suppose the theory is advanced that there is an enzyme in the liver and yeast, which causes hydrogen peroxide to turn into oxygen and water; designed and conducted a controlled experiment to test this hypothesis.

7 Record (i) the test, (ii) reasons for doing it, (iii) observations

its results and (iv) conclusions.

(h) Wash the test tubes. Design and experiment to see if the enzyme you think is in plant and animal material can be extracted and still retain its properties. The test should include a control.

8 Briefly describe your process, your results and your conclusions.

9 Assuming that the liver and yeast each have an enzyme that splits hydrogen peroxide, is there any evidence that it is the same? What would have to be done to see this for sure?

Discussion – answer

1 Effervescence should be observed in each case but is much stronger with yeast than with liver. A bright foot should shine.

2 Oxygen is produced.

3 There is no evidence to show whether water or solids are supplying the gas. If students think that a solid is unlikely to give off a gas, they may be reminded of limestone and hydrochloric acid in which a solid produces carbon dioxide. It seems that at least, however, both yeast and liver will give oxygen when treated with hydrogen peroxide, than hydrogen peroxide should give oxygen when treated with different substances.

4 So far, there is no evidence of an enzyme involved.

5 The gas will come off but not fast enough to light a splint. Charcoal is not hard

is an enzyme because (a) it is an element and (b) it is produced by very high temperatures that will destroy enzymes.

6 Coal, as a material, cannot give oxygen. The gas must be coming from the

hydrogen peroxide.

7 (i) The test should involve boiling the tissues and then placing them in hydrogen peroxide.

(ii) If an enzyme is involved,

(iii) no gas will be produced.

8 The student should grind the samples with a little sand and distilled water, filter and test the filtrate with hydrogen peroxide. Oxygen will be developed with a strength corresponding to that witnessed when the original articles were tested.

The student must cook each half and show that he lost his activity.

9 There seems to be no special reason why yeast and liver should not have different enzymes which catalyze the digestion of hydrogen peroxide. To be sure on this point, the enzymes will have to be extracted and their chemical composition determined.

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