Enzymes at Work – Testing Catalase and Hydrogen Peroxide
Enzymes are biological catalysts that speed up reactions in living organisms without being used up. One of the best ways to see this in action is with catalase — an enzyme found in most cells, especially in the liver, that breaks down hydrogen peroxide into water and oxygen.
The Reaction
Hydrogen peroxide is toxic to cells, so catalase breaks it down quickly:
This reaction produces visible bubbles of oxygen gas, which makes it perfect for classroom investigation.
The Experiment
Students add small pieces of potato or liver (both rich in catalase) to hydrogen peroxide and observe how quickly bubbles form. The faster the bubbles appear, the faster the enzyme is working.
Variables to explore:
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Temperature – warming speeds up the reaction until the enzyme denatures.
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pH – catalase works best around neutral pH.
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Surface area – smaller pieces or blended samples react faster.
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Concentration of hydrogen peroxide – higher concentration gives faster reaction rates.
The rate can be measured by:
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Collecting oxygen in a gas syringe, or
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Measuring foam height in a test tube, or
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Timing how long it takes to produce a set volume of gas.
Typical Results
| Temperature (°C) | Volume of O₂ in 30 s (cm³) |
|---|---|
| 0 | 2 |
| 20 | 18 |
| 40 | 25 |
| 60 | 10 |
| 80 | 0 |
The results show enzyme activity increasing with temperature up to an optimum (around 40°C) before falling rapidly as the enzyme denatures.
Why It Works in Teaching
This investigation shows students how enzymes depend on structure and conditions. They can see and measure the reaction, test different variables, and link results to the lock-and-key theory.
It is hands-on biology that reinforces both experimental design and molecular understanding.
Conclusion
Catalase offers a clear, visible, and measurable way to study enzymes. Students not only observe oxygen being released but also understand how factors like temperature and pH control enzyme activity — and why enzymes are vital in every living cell.
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