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investigate how temperature and surface area affects the rate of reaction of the enzyme catalyse on its substrate hydrogen peroxide.

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Investigation Aim To investigate how temperature and surface area affects the rate of reaction of the enzyme catalyse on its substrate hydrogen peroxide. Planning and investigational procedures Background information Enzymes are biological catalysts, which increase the rates of reactions. Enzymes increase the rate of reactions by lowering the activation energy needed for the reaction to start. The activation energy is the amount of energy needed, for molecules to react. Activation energy is required to break bonds and this causes molecules to react. When molecules collide they need a certain amount of energy to react and sometimes if enough activation energy is not present the molecules will collide but not react. The collisions theory is when molecules collide with each other to start a reaction. The molecules will only bounce off each other if the activation energy is not reached. The active site of an enzyme is where the reactions will take place or break down a substance. Only a certain enzyme will work on any substance this is called the substrate. The substrate of lipase is fats and for amylase it is starch. Only one substrate can be broken down by an enzyme, because the active site is different for each enzyme which means only one substance can fit. The 'lock and key theory' states that enzymes are like a lock where only one key can fit. Reactions in which large molecules are built up from smaller molecules are called anabolic. The opposite of anabolic reactions are called catabolic. These reactions are drawn below. . These reactions are drawn below. ...read more.


Place goggles on face gather together 2 beakers and 2 test tubes. Put tap water in one beaker and get the temperature of water that you are going to use in the other. Use a borer to get a strip of potato and cut the potato strip into the desired length and put the capacity of hydrogen peroxide into a test tube. Fill the other test tube with water and place your thumb over the top to prevent gas escaping. Place the potato in the same test tube as the hydrogen peroxide and place a bung over this test tube. Place this test tube in the beaker with the water to your selected temperature and place a delivery in the other test tube while it is in the other beaker upside down start the stopwatch and read the amount of bubbles that come out. Repeat the experiment twice for reliability and to find an average. Do the experiment at various different temperatures at least 6 to see the difference that temperature makes. Make sure the temperature of the substrate has reached the temperature of the water that has been modified before adding the potato and as soon as the potato has been added start the timer. There are also other methods which can be used these include measuring the mass of the gas lost but this type of specialist equipment is not readily available. I will make sure that a fair test is conducted by: * Using the same length of potato * Using the same volume of Hydrogen Peroxide * ...read more.


My results are reliable enough to draw a conclusion, as there was a reasonable pattern even though it did not follow the Q10 factor. The line graph showed some sort of pattern however; it was not a very distinct pattern but you could see that at up to 45�c the pattern rose slowly upwards but after it is not all a decrease and there is some increase especially 50�c and 70�c. I might have improved my method to obtain more evidence to support my conclusion by leaving the experiments for a longer time. This may have had an effect because if it was left for three minutes some temperatures may have stopped reacting at 2 minutes and 10 seconds while some may have gone all the way through to 3 minutes that may have made the graph and the results more accurate producing a more valid conclusion. If I also used more potato or a more or higher concentration of hydrogen peroxide I also may have got more accurate results. I think that I used more temperatures in between E.g. 15 and 25�c there might have been more accurate results as I could see the exact difference that say 3�c would make on the amount of bubbles produced. Some better investigations that could be carried out to extend this investigation are if I measured the mass of gas lost, as digital equipment is used. Also if more electrical equipment were use human error would be eliminated. By Daniel McIntosh ...read more.

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