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GCSE Biology Coursework- The effects of a named variable on the action of the enzyme trypsin

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GCSE Biology Coursework- The effects of a named variable on the action of the enzyme trypsin Background Knowledge: Enzymes are biological catalysts that speed up the rate of reaction without themselves being used up. These reactions do not change the catalyst and so, even small amounts of enzyme can do a big job. Enzymes are composed of polymers of amino acids. Enzymes also are: * Protein- whose chemical shape is special to the substance it works on. * Specific- starch alone fits into the special shape of the enzyme salivary gland, not protein or anything else, so starch alone is digested by it. * Temperature Sensitive- boiling destroys enzymes (by altering their shape); cooling only slows down their action. * PH Sensitive- each enzyme has its own optimum PH e.g. optimum pH for pepsin is pH2 (acid); for salivary amylase pH6.8 (almost neutral); and for lipase pH9 (alkaline). Collision Theory Chemical reactions take place by chance. Particles need to collide with enough velocity so that they react. As the temperature is increased the particles move faster since they have more energy. This means that they are colliding more often and more of the collisions have enough velocity to cause a reaction. Since there are more collisions the chemical reaction takes place faster. ...read more.


The opposite is true if the temperature is lowered. Apparatus/Equipment: Apparatus List: The apparatus list is as follows: a beaker to hold the water in; photographic film to be experimented on; a splint to hold the photographic film; a kettle to boil the water; trypsin to react with the photographic film; a thermometer to measure the temperature of the solvent; a test tube to do the experiment in; and a stop watch to see how long it took for the photographic film to clear. Fair Testing: to make it a fair test, I will state what variables will be controlled and how. The size of the photographic film will be controlled as I will cut it to size 1cm ? 1cm by using a ruler. The temperature of the trypsin will be made sure as it will always have a thermometer in it and it will be constantly monitored throughout the experiment. The amount of the trypsin used in each experiment will be the same as will the amount of water in the beaker. The size of each beaker and each test tube will be the same for each experiment conducted. The dependant variable in this experiment is "how long it takes for the photographic film to go clear." ...read more.


As we have to move splint (holding the photographic film) up and down in the trypsin solution, this may have also affected the results, as the speed was inconsistent and not monitored. This inaccuracy at 40?C is also seen in Graph 2, which shows the average Rate of Reaction of the enzyme trypsin at a range of different temperatures. However, I do believe that the results are sufficient enough to support a firm conclusion. This is because the results and the graphs clearly show that the higher the temperature the faster the rate of reaction between the enzyme trypsin and gelatine layer in the photographic film. This conclusion had been reached throughout each separate experiment. There are many improvements I could make to this experiment that would give me more accurate results. Instead of using of using a thermometer, I could have used a Loggit or an electronic water-bath, which would have ensured that the temperature remained constant and would have given me an accurate reading. Also, I could have used a wider range of temperatures, which would have given me a greater idea of what temperature it would have taken for the enzymes to be completely denatured. I should have also taken more sets of results as this would have made identifying any anomalous results easier and it would have also made my experiment more precise. Sources of Information: Internet sources GCSE Biology books A level Biology books SHAMIMA SHALLY 11TI ...read more.

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