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Find out if different concentrations of catalase (in this case yeast suspension) change the rate of reaction.

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Introduction

Seb Jenner 10A Catalase Investigation The aim of this investigation is to find out if different concentrations of catalase (in this case yeast suspension) change the rate of reaction. We are using yeast suspension as the catalase because it is very easy to use and it is the most reactive out of the ones that we tested. Enzymes are made up of protein molecules, they are also catalysts, this means that they speed up biological reactions. Each type of enzyme can only speed up one kind of reaction, this is because each enzyme's active site is a different shape and so it can only speed up the reaction of the molecule with the complementary shape. (AQA GCSE Science) Catalase is found in every cell, it is needed because hydrogen peroxide is poisonous, the catalase reacts with it to divide it into water and oxygen. This is a diagram of catalase: Catalase increases the reaction rate of the decomposition of Hydrogen Peroxide into water and oxygen. This equation shows this: Catalase Hydrogen Peroxide---------------------->Water + Oxygen Catalase 2H2O2 ------------------->2H2O+O2 This is a diagram showing how substrates fit together with enzymes into the active site (borrowed from John Grantham) ...read more.

Middle

Apparatus * 1 boiling tube * 1 measuring cylinder * 1 delivery tube * 2 syringes (1cm3) * 1 beaker * yeast solution (5 %) * hydrogen peroxide (10%) * Bung * Needle My preliminary experiment showed me that I should use 1cm3 of yeast and 1cm of hydrogen peroxide, this was because they were very reactive and also because if I used more than 1cm3too much oxygen would be displaced. It also showed me that yeast solution was the best catalase to use because it produced the most froth, meaning it had a higher reaction rate. The preliminary experiment also gave me a chance to get accustomed to the equipment that I would be using in our investigation. I plan on recording the increase in oxygen by recording the decrease in water in the measuring cylinder. I will record my results every five seconds up to thirty seconds. Method * Put 1cm3 of hydrogen peroxide in test tube. * Put the bung (attached to the delivery tube) on the test tube. * Place the delivery tube in a beaker of water. * Place a measuring cylinder filled with water over the delivery tube. ...read more.

Conclusion

of yeast % 5 seconds 10 Seconds 15 seconds 20 seconds 5 3 5.5 7.5 10 4 1.5 3 5 7.25 3 1 1.75 4 5.5 2 1 1 2.5 4 1 0.25 0.75 1 2 0 0 0 0 0 The Graph on the next page and the results above show that the greater the concentration of catalase, the more oxygen is produced in a shorter space of time. This is because there are more catalase molecules and so more collisions, therefore the Hydrogen Peroxide molecules can be broken down faster too Oxygen and water. One thing that I would have expected to see was a limit in the speed that the reaction occurred with the different concentrations. I obviously should have continued my experiment to achieve these results. I believe that my results were fairly accurate, however to improve them I could have repeated the experiment, and continued for more than 20 seconds. A problem that I could not overcome was the reliability of the human eye. I may have misread the volume on the measuring cylinder, however without expensive machinery I could not achieve perfection. ...read more.

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