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Effects of Surface Area on Catalase Activity in Potato.

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Effects of Surface Area on Catalase Activity in Potato Aim To investigate the effect of surface area on the activity of Catalase in potato. Hypothesis I predict that the potato which has been cut into more pieces will have the largest surface area. A larger surface area means that there will be more catalase molecules coming in contact with the reacting substrate, hydrogen peroxide. Enzymes react when particles come into contact with their active sites; if more of the enzyme is exposed (larger surface area) a greater number of active sites will be available to react with the hydrogen peroxide. The surface area of a 5cm tube with a diameter of 2cm equals 37.0 cms� ( 2 rh+2 r� ), but a 5 cm tube cut into five 1cm segments has a surface area of 62.83 cms�. Every time another segment is cut from the 5cm tube two more areas have to taken into account, this means each time the 5cm tube is cut into a piece the surface area will increase. As a larger surface area produces a higher rate of reaction, my results should show a higher volume of gas released when using a potato with a larger surface area. Background Knowledge Enzymes are proteins which can be referred to as biological catalysts. Catalysts are molecules which increase the rate of chemical reactions and remain unchanged at the end of the reaction. ...read more.


Temperature increases the kinetic energy of the reacting particles, this extra energy creates more successful collisions between the reacting particles thus increasing the rate of reaction. But as the enzyme holds a specific three-dimensional shape, too much heat can distort the hydrogen bonds in the enzyme particle structure and cause the enzyme to become denatured; when an enzyme becomes denatured it no longer possesses its catalytic abilities. When performing the experiment the reactions of the different surface areas are to be performed in the same temperature to avoid anomalous results. I will use the room temperature for all the reactions; preliminary experiments show reactions occurring under room temperature conditions, this means room temperature will not denature the enzyme and will contribute into providing a reliable set of results. pH - an increase or decrease of the pH level of hydrogen peroxide will also denature the enzyme Catalase. A decrease of pH will cause the H+ ions in the enzyme particle to become attracted to the abundant negatively charged ions in the enzyme; this will change the shape of the enzyme causing it to become denatured. There will be no change of the pH level of hydrogen peroxide throughout the experiment as changing the pH level will disrupt the rate of reaction and cause anomalous readings. Concentration of catalase - the concentration of the catalase will be kept the same for all the reactions. ...read more.


3. Using the syringe, measure out 20 cm� of 0.1M hydrogen peroxide into the boiling tube. 4. Fill the water container and measuring cylinder with water. The measuring cylinder should be held upside down, with the end of the delivery tube positioned in the open end of the cylinder. 5. Place the potato into the boiling tube, then quickly, holding the delivery tube push the bung into the top of the boiling tube. 6. Start the stop watch and collect oxygen for five minutes. Record the amount of oxygen released at the end of the 5minute timing. 7. Discard the contents of the boiling tube. 8. Repeat the experiment using the other potato's with surface area variations. 9. When results for all of these combinations of cylinders have been obtained, repeat procedures 1-8 again to obtain a second set of results; to be used in obtaining an average set of results. Number and Range Potato cylinders to be used Concentration of H2O2 to be used 1 5cm 0.1 M 2 2.5cm 0.1 M 5 1cm 0.1 M Health and Safety Regulations Hydrogen peroxide is corrosive and can cause damage if it enters the eye, to eliminate this risk occurring when performing the investigation safety goggles should be worn throughout the experiment. The cork borer being used can also cause damage to the body. When using the cork borer remember to keep hands away from the area of exit of the cork borer. The scalpel must be used carefully on the white tile. Also all glassware used in the experiment should be handled with care. ...read more.

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This is an outstanding introduction to a practical.
1 - The language used is concise and demonstrates a good scientific vocabulary.
2 - The information is well researched and only relevant information has been included.
3 - There are very few errors in structure or language.
4 - The range of the practical needs to be revisited as the interval is not standardized.
5 - Any information that has been included needs to be referenced.
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Marked by teacher Luke Smithen 24/04/2013

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