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Potato Discs - investigate how the number of potato discs and therefore the surface area of the potatoes affect the amount of oxygen produced when in a reaction with hydrogen peroxide,

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Introduction

Biology - Potato discs experiment Aim: To investigate how the number of potato discs and therefore the surface area of the potatoes affect the amount of oxygen produced when in a reaction with hydrogen peroxide, Apparatus: * 1 Measuring Cylinder, 25cm3 (to measure out hydrogen peroxide in) * 1 Boiling tube (to place potato discs and hydrogen peroxide into) * Cork borer (to cut out a piece of potato from the whole potato) * 1 Timer (to count to 3 minutes to see how much oxygen and water goes through to the delivery tube) * Beaker (to put water into) * 1 30cm ruler (to measure length of potato discs) * 1 Potato (used instead of catalase to see difference in volume) * 1 M Hydrogen Peroxide Solution (used as the solution to react the enzyme catalase as it acts as substrate for the potato to react with) * Scalpel (to cut potato discs) * Delivery Tube (to transfer oxygen and waste produced to boiling tube) * Bung (to ensure that no water or oxygen escape from the delivery tube) * Tile (to cut potato discs on with a scalpel) Safety In this experiment it is essential that you wear safety goggles as goggles will prevent any chemicals or solution from entering your eyes, this is a precaution in case something goes wrong in the experiment and the solutions splash towards your eyes. ...read more.

Middle

Control Variables: Hydrogen Peroxide volume and concentration These affect the rate of reaction as when there is more substrate concentration (Hydrogen Peroxide) there is an increase in the rate of reaction. For this reason I aim to control the substrate concentration by using the same quantities and concentration of the substrate Hydrogen Peroxide for each different experiment with different amounts of discs. pH level: It is essential to control the pH level as a change in pH would affect the ionic and hydrogen bonding in an enzyme and so it would alters its shape and its active site so the reaction may not be catalysed. Every enzyme has an optimum pH at which its active site best fits the substrate and the reaction is catalysed. Difference either side of the optimum pH, results in unwanted conditions of the enzyme and a slower rate of reaction, which would make my results unreliable if this was different in every reaction, for this reason it is essential that I control this variable. To control this in my experiment I will use potato discs from the same potato this means the pH level will be controlled as the same potato throughout on average will have the same pH, also the same quantity of Hydrogen Peroxide was used for each experiment. ...read more.

Conclusion

Moreover, If I was to do the experiment again I would measure the potato pieces using a micrometer, this would provide a more accurate sized piece of potato and this would mean a much more accurate set of results. Additionally, if I was to redo this experiment I would also repeat each experiment, as I only did one experiment for each number of potato discs however, if I was to do more repeats I would have a better average as I would have more results and therefore my results would be more reliable. Despite these minor mistakes I am confident in my conclusion as most of my results follow a pattern and the procedure in which the experiment was taken out, is pretty accurate. Finally, the potato discs may have stuck to each other, blocking one of the ends from releasing enzymes, this means that a full reaction may not occur and I will not get accurate results due to this, so if I was to redo this experiment I would ensure that the potatoes are touching each other as little as possible. All in all, from this experiment I have learnt that an increase in the number of potato's, and therefore an increase in surface area (an increase in the enzyme catalase) there is more gas and water produced ?? ?? ?? ?? Kastriot Jonuzi ...read more.

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