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Investigating Enzymes and the effects of different variables such as temperature on how they work

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Investigating Enzymes and the effects of different variables such as temperature on how they work By Luke Warner Contents Introduction Chapter 1 - Preliminary experiment Chapter 2 - Method Chapter 3 - Equipment Chapter 4 - Results tables Chapter 5 - Graphs of results Chapter 6 - Rate of reactions with averages Chapter 7 - Rate of reactions (averages) graph Conclusion Evaluation Introduction The aim of this experiment is to study how different variables can affect enzymes. We will be investigating catalase, an enzyme present in peroxisome, which is found in most cells. Catalase is an enzyme that converts hydrogen peroxide into water and oxygen. The word and symbol equations for this are: Hydrogen Peroxide Water + Oxygen 2H2 O � 2H2O + O2 Catalase is essential for organisms because it eliminates harmful hydrogen peroxide, a by-product of many metabolic processes. Catalase also oxidises some toxins, namely formic acid, formaldehyde, alcohols and phenols. Chapter 1 - Preliminary experiment The experiment Originally, we performed the experiment by dicing up potatoes, placing them in a test tube, adding a drop of detergent and then finally 10cm3 Hydrogen Peroxide (H2O2). To measure the rate of reaction, we measured the height of the bubbles. However this was not very accurate because the bubbles popped often, and kept on changing in height. The results also contained lots of variation, and two outliers. Temperature Rate of Reaction (Vol. ...read more.


Chapter 3 - Equipment Here is a list of the equipment we used in our experiment: * Measuring Tube: This shall aid us in measuring the H2O2 that we add to yeast. * Conical flask: the neck allows the bong to fit perfectly without losing any gas given off, although some may be if we do not act quick enough. * Water bath: Water sustains heat more, so it is more efficient and helps maintain the needed temperature without losing heat. However the time spent walking towards the experiment will cause heat loss. * Gas Syringe: This allows for more accurate reading of the O2 given off. Some gas syringes may however get stuck. * Clamp: Holds the gas syringe. Too tight could cause it to break. * Clamp Stand: Holds the clamp in place. Chapter 4 - Results Tables OS: Off Scale 1. Volume of Oxygen (cm3) at each interval (s) Temperature (�C) 0 10 20 30 40 50 60 70 0 10 25 35 45 50 55 60 65 20 15 30 40 60 70 90 OS OS 40 10 20 35 50 60 70 75 80 60 5 25 45 65 85 95 OS OS 80 0 10 10 10 10 10 10 11 2. 10 20 30 40 50 60 70 0 20 30 40 50 60 70 80 20 30 40 45 60 80 90 95 40 45 65 82 OS OS OS OS 60 20 40 55 70 85 100 OS 80 6 7 8 10 10 10 10 3. ...read more.


Another problem is how our apparatus may not have been 100% accurate. As I explained earlier my error bars varied a lot, and this may have been a result of anything I have previously mentioned. Our results had 3 outliers that were all too high. These were at 80, 60 and 0�C. This may have been that with the other set of results we repeatedly made errors, or we read the gas syringe wrong for the results with outliers. Our results, as I said before may not have been particularly accurate. The error margins that may have been present in our experiment was +/-0.5cm3. If we take the results for 60�C (0.9cm3/s), then we can do the following: 0.5 X 100 = 55.55% 0.9 Unfortunately I am not perfectly confident with my results as a due course of the varying error bar size, and possible faults in our method. Next time I perform the experiment, I will do the following: * Do more than 3 experiments to get a more accurate average. I believe that a reasonable amount of repeats would be 5 times. Outliers would then have a smaller effect on our results. * Thoroughly clean the apparatus to stop possible problems as results of previous experiments. We could do this by using water to clean out certain apparatus (e.g. measuring cylinder or conical flask) * Vary the temperatures more. I could experiment with using sub-zero temperatures to see just how much of an effect they may have on our results. * Use different concentrations of hydrogen peroxide for the same reasons as above. ...read more.

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Here's what a teacher thought of this essay

4 star(s)

An excellent GCSE level experiment report, containing a clear method based on a relevant trial experiment. Results tables, conclusions and data interpretations are clear, and the evaluation is adequate. To improve:
1)Identify the dependent variable, independent variable and control variables clearly
2)Clearly explain why the sources of error that are identified will reduce the reliability of results (eg inadequately cleaned equipment) or the accuracy of readings (eg some oxygen escaping)
3)Think through the method improvements that are proposed more thoroughly. Think about how the sources of error identified could be eliminated and how a more precise conclusion about optimum temperature could be reached

Marked by teacher Kerry jackson 15/02/2012

Here's what a star student thought of this essay

4 star(s)

Response to the question

An excellent response to a coursework expected of a GCSE student. Well structured and explains basic science behind the investigation (what catalase is) well and data from table is referred well throughout. To improve briefly explain what is meant by ...

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Response to the question

An excellent response to a coursework expected of a GCSE student. Well structured and explains basic science behind the investigation (what catalase is) well and data from table is referred well throughout. To improve briefly explain what is meant by accurate,reliable and outlier. Clearly state different variables using key words (independent, control etc).

Level of analysis

Data is used within coursework to relate to the question although level of analysis is too basic at some parts. For instance when referred to denatured, the student could improve his mark by explaining in detail why enzyme is denatured (referring to optimum temp) to ensure clarity of his point. To further improve, student could create a list of factors affecting experiment (incomplete cleaning of equipment for eg).

Quality of writing

Key words are used well to show students' understanding of topic. Align the text so its easier to follow and understand. Spelling and grammar is good.

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Reviewed by nilabkebab 10/08/2012

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