About Lesson
Practical Activity: To demonstrate the action of enzyme catalase
Enzyme catalase is found in most living cells.
It breaks down toxic hydrogen peroxide, a by-product of cell metabolism, into no-toxic oxygen and water.
Requirements
- liver
- Hydrogen peroxide
- Scalpel
- Measuring cylinder
- Test-tube
- Wooden splint
- Means of heating
Procedure
- Put about 10 cm3 Hydrogen peroxide into a test-tube.
- Cut small pieces of liver and place them into the test-tube.
- Record your observation.
- Hold a wooden glowing splint inside the mouth of the test-tube.
Results and explanation
- When pieces of liver are placed into hydrogen peroxide, there is very fast fizzing and a gas is given off.
- When the glowing splint is introduced at the mouth of the test-tube, it relights suggesting that oxygen is given off from the reaction taking place.
- It was necessary to use small pieces of liver instead of one big to increase the surface area hence exposing more enzymes that come into contact and react with hydrogen peroxide.
- If boiled liver was used instead of a living one, there would be no effervescence due to no evolution of oxygen. This is because boiling denatured the enzyme catalase in the liver cells.
- If some chopped raw potato was used instead of liver there would be less fizzing since potato tissue contains less enzyme catalase.
- If concentrated hydrochloric acid could have been boiled with the liver pieces there would be no fizzing hence no evolution of oxygen. This is because high acidity denatures enzyme catalase in the liver cells.
- Potatoes which are about to germinate and liver cells contain a lot of catalase enzymes.