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Affects of Temperature On the Digestion of Starch.

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AFFECTS OF TEMPERATURE ON THE DIGESTION OF STARCH PAUL MITCHELL SCIENCE COURSEWORK Affects of Temperature On The Digestion of Starch * Introduction For my experiment, I will be looking at enzymes; more specifically, the enzyme amylase. Amylase breaks down starch into glucose. I will be looking at how temperature affects this conversion. Enzymes exist in all living things. They are composed of polypeptide chains of amino acids and are produced in living cells. Each cell contains several hundred enzymes, which catalyse a vast number of chemical reactions. Enzymes are known as 'Biological Catalysts' as they dramatically affect the rate at which reactions occur within living organisms, without being 'used up' or effecting the reaction in any other way. Enzyme catalysis saves the need for an increase in temperature in order to speed up reactions within living things. Such an increase in temperature would be lethal to the organism. Enzymes only control the rate of one specific reaction inside the body, as only one specific substrate can fit into its active site; therefore we say the enzyme is specialized. There are two main types of enzyme: * Intracellular enzymes, which control reactions that occur inside cells. * Extracellular enzymes, which control reactions that occur outside cells All enzymes are affected by temperature and pH. They have an optimum range of the two, and anything outside this range will denature the enzymes "active site." The enzymes that are used in reactions inside our bodies have an optimum temperature of 37oC.


* Add 2 drops of iodine solution to test for the presence of starch and wait for the solution to change to a black/purple colour. * Repeat this every 30 seconds until the solution no longer changes colour; therefore indicating all the starch being converted into glucose. * Once the iodine stops indicating a black colour, stop the stopwatch. * Record the indicated time on the stopwatch into the results table below. * Then, add a few drops of Benedict's to the solution and put the boiling tube into a hot water bath. * Wait until the solution has turned a brick red colour; thus indicating all the starch being turned into glucose. The same process as above should be carried out for every experiment. (A, B, C, D, E, F and G.) When using a water bath instead of an ice bath, set this up by adding water into the bath. Light the Bunsen-burner and keep it on a safety flame until the Bunsen is being used to heat up the water. When the water reaches the correct temperature, pull the Bunsen away to keep the water from overheating. * Results: After completing my experiment, my results are given below in a table. I have also plotted my results onto scatter graph to show the variance in time against temperature. A 5 14 B 15 11 C 25 8 D 35 3 E 45 9 F 50 13 G 65 No Reaction * Conclusion: In conclusion, from the results of my experiment, I can see that the basic theory behind my prediction was proved correct.


If I had the use of an electric water bath, I could have kept the accuracy of the test better, resulting in more accurate results. Another main aspect I could improve on for my experiment is to make the results I received from my test fairer. I could achieve this by repeating each test three times and then taking the average time from the three. This would have given me a more likely result time for the digestion. I could also increase the time from which I took a sample from each boiling tube. Instead of taking a sample every 30 seconds, I could take a sample every 10 or 15 seconds. This would result in a truer reaction time. I could also take a wider range of temperatures to pinpoint the specific optimum temperature, and the specific temperature that the enzyme denatures. I could do the same experiment changing the pH of the solution, to see how that affects the enzyme and which pH is the best for the conversion of starch into glucose using amylase. One other aspect to take into account on improving my experiment is my own personal practical skills. I feel that I carried out the experiment to the best of my ability. During the experiment I could have kept a little more level headed and patient, so that I could pay more attention to the task and receive better results. If I had a little more time to complete the experiment, and things where not as rushed, then I feel I could have improved on the accuracy of my results. Biology Coursework Paul Mitchell

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