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# The effect of enzyme concentration on the rate of reaction of the enzyme catalase.

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Introduction

Biology Practical Assessment: The effect of enzyme concentration on the rate of reaction of the enzyme catalase. Skill G: Interpretation of Results Table of class results to show the effect of catalase concentration on the rate at which oxygen gas is released. Catalase concentration/% Volume of oxygen gas released in 2 minutes/cm3 Mean volume of oxygen/ cm3* Rate/ cm3 min-1 1 2 3 4 5 6 7 8 9 10 20 14 15 29 18 18 16 20 16 16 15 18 9 40 27 24 56 43 39 27 29 25 38 33 34 17 60 45 50 69 59 42 36 54 55 54 52 52 26 80 60 66 77 75 68 49 61 60 79 61 66 33 100 73 70 84 86 79 66 82 79 93 66 78 39 *The mean volumes were rounded to whole figures as the measuring cylinder measured to the nearest cm3 Anomalous results Trends and Patterns The general trend of the graph shows that as the concentration of catalase increases, the rate at which the oxygen is produced increases. At a concentration of 20% catalase, the rate is 9 cm3 min-1, and this increases to 26 cm3 min-1 at 60%, before increasing further to 39 cm3 min-1 when the catalase concentration is at 100%. ...read more.

Middle

Furthermore, when 40 and 60% catalase was reacted with hydrogen peroxide, group 3's results were again higher than other group's where 56 and 69 cm3 of oxygen gas was recorded. These were especially high against the mean volumes which were calculated to be 34 and 52cm3 respectively. However, group 6 recorded volumes lower than the calculated mean and recorded 36 cm3 of oxygen gas being produced against the mean of 52 cm3 when the concentration of catalase was 60%. Again, for 80% catalase solution, the recorded value was lower than the mean of 66 cm3, with group 6 having recorded 49 cm3 of oxygen been given off. The final anomalous result highlighted in the results table comes from group 9 who recorded a volume of 93 cm3 of oxygen gas. Again, this is anomalous, as like others before it, it is significantly higher than the mean which in this case was 78 cm3. Reasons for such anomalies range from biological variation of the catalase -as the solutions consisted of a suspension of yeast cells- to variation between some group's methods, specifically differences in the time it took to remove the rubber bung. ...read more.

Conclusion

Furthermore, group 9's high anomalous result of 93 cm3 of oxygen for 100% catalase against the mean of 78 cm3 may suggest that their catalase was more pure than other groups. However, I think it is more likely that in this instance this group may not have remembered to have shaken the bottle of catalase therefore would have extracted more catalase and less solvent. A way to improve this would again be to use a magnetic stirrer to ensure that the suspension was equally distributed with those yeast cells containing a high concentration of catalase, and those containing a low concentration of catalase. Finally the least influential error would have been the number of concentrations of catalase used. Although a wide range of concentrations was used, it may have been useful to make up other, closer together concentrations such as 25, 30 and 35% to observe the effect of enzyme concentration more accurately. However, for those higher concentrations this would be difficult to do as the reactions were so rapid. The reason for ranking this as least influential is that the concentrations used had already provided evidence that as enzyme concentration increases, so does the rate of reaction. ?? ?? ?? ?? Farah Aslam 1 ...read more.

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