Two drops of starch solution are put into the first
dimple as a control.
10ml of starch solution and 1ml of amylase is measured using the syringe. The Starch is put into a test tube, and then the amylase is added, and the stop clock is
immediately started. With a pipette, 3 drops of the starch and amylase solution are added to each dimple every thirty seconds. When the solution has turned back to the original colour of the iodine solution the stop clock is stopped. I will take 8 results and repeat all of them once and any results I think are abnormal, to make sure my results are accurate. I will start at 10 degrees, and then increase the temperature by 10 degrees more every time till 80 degrees. To get accurate temperatures needed for the experiment I am using a water bath, Bunsen burner and thermometer. I will keep the same person to decide whether the starch has been broken down as everyone has different eyes and what we see is different. I could look at other students results in this field to confirm my results.
I want to keep the starch solution, iodine and amylase solution constant through out the experiment, I will only change the temperature to make the experiment a fair test.
Prediction-
Using scientific knoledge I can predict that the enzyme will work best around 30.c – 40.c as this is around body temperature, and amylase works best around body temperature. At high or low temperatures I think that the amylase will work more slowly than at 30.c. At 70- 80.c I think that the enzyme will be denatured, we can tell this by the Iodine solution showing us that the starch has not broken down.
Obtaining evidence.
I have recorded my results in a table, then a graph.
Temperature (.c) time took to break down starch
Of starch solution minutes and seconds
1. 2. Average
10 15.30 24.00 19.45
20 16.30 19.00 17.45
30 9.00 16.30 12.45
40 6.30 6.00 6.15
50 2.00 2.00 2.00
60 4.30 4.00 4.15
70 4.30 5.30 5.00
80 1.30 denatured
I have put my results in a graph, and have drawn a best-fit line. I circled any anomaly results in red. This result I will ignore when making my conclusion. I repeated the experiment at 80.c as the result I got from the first try did not fit in with the pattern. When I repeated I this, I carried the experiment on for 10 minutes, and the colour did not change from black, the same colour as the control, so I decided that it had denatured.
Conclusion
Most of my results fit a regular pattern, as the temperature increases from 10.c- 50.c the time decreases. As the temperature increases from 50.c – 80.c the time increases.
This means that amylase breaks up starch best at around 50.c. In cold temperatures
Amylase works slowly, and the nearer to 50.c amylase works more quickly. In hotter temperatures, the amylase either denatures or begins to work slowly again.
From the table and graph I can see that from 20.c when you increase the temperature by 10 degrees, you decrease the time by 5-6 minutes, down to 2 minutes.
My prediction was wrong as I said that the amylase would work best at 30- 40.c, where as my results show me that it works best at 50.c. I did predict correctly that the reaction would be slowest at either low or high temperature, and would denature around 70- 80.c.
Evaluation.
I found it difficult to keep the temperature of the starch constant when doing the experiment. If I did this experiment again I would keep the solution of starch and amylase in a water-bath of the right temperature. I think that because the temperature cooled down as time went by my experiment wasn’t totally accurate.
I decided that the experiment at 80.c did not fit the correct pattern, so I repeated it. The second time it gave me the results I predicted.
The timing might not have been exactly accurate and this could have effected my results.
If I did this experiment again I would want to use a water-bath for more accuracy in controlling the temperatures. Also I would have liked to repeat all of the experiment one more time, so that my average would be more precise, with 1 or 2 results, they can not be that reliable.
