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To investigate the effect of Diastase on Starch

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To investigate the effect of Diastase on Starch Aim The aim of this experiment was to investigate the breakdown of starch by diastase. There where a lot of different variables that could be changed. The possible variables that could be changed were: 1. Temperature The temperature of the water that the reaction was carried out in could be changed. 2. Concentration of Starch The concentration of the starch that will be used can be changed. 3. Concentration of Diastase The concentration of the diastase that will be used can be changed. 4. pH of Solutions The pH of both the solutions could be altered. 5. Volume of Starch The amount of starch that is used could be changed. 6. Volume of Diastase The amount of diastase that is used could be changed. 7. Amount of Iodine used The amount of iodine that is used could be changed. 8. Agitation The amount of agitation the test-tube is subjected to after the solutions are mixed. The variable that I am going to change is temperature. This is because it is one of the easiest to control and is almost guaranteed to get accurate results. Research in to Enzymes Enzymes are biological catalysts made up from protein that control vital biological processes. ...read more.


Then the diastase will no longer catalyse the breakdown of starch. This is because diastase is made up of protein molecules and therefore it is easily denatured by heat, losing it's shape and no longer able to combine with the starch. I think the rate of breakdown of the starch will increase until this point because the increase in temperature will supply the molecules with more energy to react, and then it will slow down and the rate of reaction will be a lot longer. I predict the final graph will look like the one below, which clearly shows that the results are indirectly proportional to each other. This means that as one of the variables increases, temperature the other one decreases, time. But once the temperature reaches between 45oC to 55oC the time will slow down until eventually the reaction that occurs between the diastase and starch will be too slow to record. I have decided to take three readings for each temperature and then take an average. I believe that this will achieve the best results possible. Time Taken to Disappear (Seconds) Temperature (oC) Previous Work Prior to this experiment, a pilot study was carried out. ...read more.


The temperature was then changed and the whole experiment repeated again. Time Taken to Disappear (Seconds) Time Taken to Disappear (Seconds) Time Taken to Disappear (Seconds) Time Taken to Disappear (Seconds) Temperature (oC) 1 2 3 Average 35 21.84 32.24 29.01 27.69 40 14.17 11.36 11.24 12.26 45 8.41 7.78 10.65 8.94 50 3.56 4.06 3.48 3.68 55 2.23 1.82 1.92 1.99 Evaluation and Analysis of Results After drawing a line of best fit on my graph, I can quite clearly see that there are one or two anomalous results. These are at the temperatures of 35oC, 40 oC and 45 oC. Conclusion My results proved my prediction to be incorrect. My original prediction was that the breakdown of starch is quicker as the temperature increases until the optimum temperature (40oC) after which it begins to slow down. But after drawing my graph it is quite clear that this prediction is incorrect according to the peak temperature that the experiment was carried out at (55oC). This proves that at 55 oC the enzyme is not denatured, otherwise the time taken for the starch to disappear from the solution. I think my results were sufficient to support a firm conclusion, but if I had the chance to investigate further the effect of temperature on the breakdown of starch I would take more results focusing on the higher temperatures and try to pinpoint the optimum temperature. ...read more.

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Here's what a teacher thought of this essay

3 star(s)

This report contained some sound experimental data and there was some thought in the planning but it failed to analyze the data thoroughly or to carry out an evaluation.
The planned procedure would collect some valid evidence and the range of the independent variable and the number of repeats is acceptable. To improve the candidate should include a variables table to show how they are to be controlled, a thorough risk assessment and background references to inform the plan.
Obtaining Evidence:
The candidate has recorded five values of the independent variable but the range could be extended. The readings are repeated and recorded in clearly laid out tables. The headings of the tables could be more detailed.
Analysis and Evaluation:
The candidate has stated a valid conclusion and related this to the prediction. No evaluation of the experimental method has been carried out. To improve the candidate should try to explain the results using relevant background theory and try to account for the anomalous results. They should try to explain why the results do not agree with the prediction and propose further work to explain this.

Marked by teacher Stevie Fleming 29/05/2013

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