* to investigate the effect of substrate concentration on the activity of catalase * to evaluate a practical protocol
Wear eye protection and protect clothing from hydrogen peroxide. Rinse splashes of peroxide and pureed potato off the skin as quickly as possible...
Investigation * Use the large syringe to measure 20 cm3 pureed potato into the conical flask. * Put the bung securely in the flask – twist and push carefully. * Half-fill the trough, bowl or sink with water. * Fill the 50 cm3 measuring cylinder with water. Invert it over the trough of water, with the open end under the surface of the water in the bowl and with the end of the rubber tubing in the measuring cylinder. Clamp in place. * Measure 2 cm3 of hydrogen peroxide into the 2 cm3 syringe. Put the syringe in place in the bung of the flask but do not push the plunger straight away. * Check the rubber tube is safely in the measuring cylinder. Push the plunger on the syringe and immediately start the stopclock. * After 30 seconds, note the volume of oxygen in the measuring cylinder in a suitable table of results. * Empty and rinse the conical flask and measure another 20 cm3 pureed potato into it. Reassemble the apparatus, refill the measuring cylinder, and repeat from d to g with another concentration of hydrogen peroxide. Use a 100 cm3 measuring cylinder for concentrations of hydrogen peroxide over 20 vol. * Calculate the rate of oxygen production in cm3/ s. * Plot a graph of rate of oxygen production against concentration of hydrogen peroxide.
QUESTIONS 1 Apart from oxygen, what product is made when hydrogen peroxide breaks down?
2 Identify any anomalies or inconsistencies in your results.
3 Describe the shape of the graph.
4 Explain the shape of the graph in relevant biological terms.