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To investigate the effect of enzyme concentration on digestion of starch by amylase

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Aneela Sirfraz 18/11/02 Investigation in to the effect of enzyme concentration on digestion of starch by amylase Aim To investigate the effect of enzyme concentration on digestion of starch by amylase Hypothesis The greater the concentration of amylase the bigger the circle produced due to greater digestion of starch. Apparatus 2 petri dishes containing starch agar jelly Bunsen burner Mountain needles Cork borers Micropipette 7 test tubes Test tube rack 0.5% amylase solution Distilled water Iodine solution Felt tip pen Ruler Safety Due to the use of the Bunsen burner I shall wear safety glasses and when not using it I shall put it on to the safety flame. Also whilst carrying out the experiment I shall be careful when using the mountain needles as they are very sharp. Method * Firstly on the back of the two petri dishes I shall divide each petri dish in to 4 parts and label each one with a concentration percentage. * Then I shall light the Bunsen burner a pass a cork borer and a mountain needle through the blue flame. ...read more.


* Distilled water was used as a control because it should have no effect have no effect on the starch agar jelly. * The concentrations will be placed into the appropriate holes in the starch agar jelly using a micropipette. A micropipette will be used as it is more accurate that a normal pipette. However each time a different solution will be used a different head will be placed on the micropipette. This is to ensure accuracy and fairness and so that no drops of a different concentration should go in to another concentration. Again, when adding the concentrations, the lid will only be lift slightly from one side. * Then after leaving the petri dishes for 1 week iodine solution will be added to show the effect of the amylase. Iodine solution turns starch black / blue. So the activity of the enzyme will be estimated from the diameter of the clear circle where no starch is present. To make sure that the experiment is fair each clear circle will be measured 3 times in the way shown below: * Then to produce a table of results the average of the 3 measurements will be taken to give the average diameter of the circle. ...read more.


Evaluation I felt that the procedure carried out was as fair and accurate as it could be. However accuracy could be improved by not having to lift the lid of the petri dishes. This is because although great care was taken to ensure no microbes came in to contact with the starch agar jelly, inevitably by lifting the lid some may have. Also the cork borer used was not thoroughly sterilised. Although we passed it through it through the Bunsen burner flame that did not mean we managed to remove all the germs present. One problem that I did encounter was measuring the diameter of the clear circle where the starch had been digested. It was difficult to see clearly where one cycle ended and another started. So the effect of this is that the measurement may not be completely accurate as I would have liked. I think to overcome this problem instead of placing 4 concentrations in one petri dish it would be better and therefore more accurate to have 4 petri dishes with one concentration in each one. By doing this the diameter can then be measured in millimetres rather than centimetres. I think the effect of this problem may have led to the one anomalous result as shown in the graph. ...read more.

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