Investigation of the effect of pH on enzyme activity

Materials needed:

• Hydrogen Peroxide (substrate)
• Celery (contains enzyme catalase)
• pH buffer (vary 4,7,10,13)
• Temperature (keep temperature constant 30°C)
• Washing up liquid
• Graduated cylinders
• Plastic droppers

Method:

1. Place 10cm³ of celery, one drop of washing up liquid and 10cm³ of pH buffer 4 in a graduated cylinder.
2. Add 5cm³ of hydrogen peroxide to another graduated cylinder.
3. Place both graduated cylinders in a thermostatically controlled water bath set at 30°C for 2 minutes to allow all reagents to reach the exact temperature.
4. After 2 minutes, add the hydrogen peroxide to the graduated cylinder containing the other reagents.
5. Record the volume of foam produced after 2 minutes. The foam volume measures enzyme activity by indicating the amount of oxygen produced.
6. Repeat the experiment at pH 7, 10, 13.
7. Record results and plot a graph of results, putting temperature on the x-axis (horizontal) and volume of foam (cm³) on y-axis (vertical).

Results:

pH	4	7	10	13
Volume of foam cm³/ 2 minutes	0cm³	0cm³	13cm³	0cm³

Graph of Results: