The independent variable for this experiment is the enzyme concentration, and the range chosen is from 1% to 5% with the measurements of 1, 2, 4, and 5%. The dependant variable to be measured is the absorbance of the absorbance of the solution within a colorimeter,
Equipments:
Iodine solution: used to test for present of starch - Amylase solution - 1% starch solution - 1 pipette - 3 syringes -
8 test tubes – Stop clock - Water bath at 37oc - Distilled water- colorimeter
Method:
Amylase is an enzyme found in our bodies, which digest starch into simple sugars. For this investigation I am going to investigate the effect of the concentration of an enzyme, in this case is Amylase, on the time taken for the enzyme to fully breakdown the substrate, which in this case is starch. I am going to do this by planning an experiment, carrying out the experiment, recording any relevant results and plotting graphs from which I will be able to gain a strong conclusion. I will finally evaluate on the whole investigation.
To ensure that my result is correct, I will repeat the whole experiment twice for each concentration of amylase.
Step-by-step procedure:
1)- Prepare dilute iodine solution for the whole procedure by adding 3cm3 of standard iodine solution to 60cm3 of distilled water in a beaker.
2)- Place 10cm3 of the dilute iodine solution in a colorimeter tube using a 10 cm3 syringe.
3)- Insert the tube in the colorimeter and adjust the reading to zero absorbance.
4)- Dilute some 1% starch solution provided by mixing 5 cm3 of the starch solution with 10 cm3 distilled water.
5)- Using a colorimeter tubes which is optically matched to that used for the blank, place 10 cm3 of dilute iodine and 0.5cm3 of dilute starch.
6)- In between each reading, check that the colorimeter registers zero with the blank.
7)- Proceed by diluting the starch solution by a factor of 2 each time and measure the absorbance of 0.5cm3 of the diluted starch in 10cm3 of dilute iodine each time. Stop it when you have readings for 5 different starch concentrations.
8)- Plot a graph of absorbance against starch concentration.
Key variables:
In this experiment, I will use the same amylase concentration and quantity through out the experiment and the same starch concentration and quantity through out the experiment.
The temperature would be kept constant and at a reasonable temperature of 37oc to ensure that the enzymes are acting at their maximum and at the same time do not get denatured.
I will add the same drops of iodine solution
Evaluation of Method:
A)-This experiment measures how the different concentration of Amylase affects the rate of starch concentration; this is a valid measure of an enzyme digest starch and the relationship between them. The apparatus chosen is suitable because it enabled the digestion of starch to be measured by the absorbance of the solution.
B)-Possible safety problems with this experiment are shown on the risk assessment sheet.
Risk Assessment:
-I will wash away any spillage on my skin with water to avoid skin irritation.
-I will wear safety goggle through out the experiment.
-I will clear up any breakage or spillage that occurs using a hand glove to prevent
Glass cuts.
-I intend using an already made amylase solution, but if eventually I have to make
It by myself, I will avoid inhaling the powder (amylase enzyme).
Results: I have taken six sets of readings for the time taken to digest starch in each concentration. A graph would be plotted to see the relationship between rate of reaction and enzyme concentration. The anomalous results are marked and clearly shown within my tables of results.
Evaluation:
Looking at the result I obtained, I would say that they were accurate because it supports my prediction although there was an anomalous result in the graph I plotted. Due to the anomalous result, I had to draw a line of best fit instead of a line graph to show an overall pattern. This anomalous result must have been as a result of an inaccurate method or wrong data collection. The method used was not really suitable to collect the evidence required; this wasn't a suitable method, because it was quite difficult to read the exact number after every 1 minute. Also, this method was inaccurate because the number of drops of starch and amylase mixture that was added to the iodine solution was varied. In the method the pupils should be told the exact quantity of drops that should be added to the iodine solution. These changes and suggestions, could lead to a better result with no anomalies. If I were to do this experiment again, it would be done in a different way. I would repeat the experiment more than 6 times in each concentration to ensure that the results obtained are accurate. Apart from the one or two anomalies I had, I think the results were accurate because they showed the relevant pattern and supported my prediction as well as my conclusion. With the curve of average points in the middle of the both readings, I can say that my results were reliable and were enough evidence to support my conclusion.
Significance of Results:
When commenting on the trend shown, the degree of error must be taken into consideration.
Discussion:
The hypothesis is the experiment was: The amylase concentration increased. And it is supported when the results are analysed.
Conclusion:
This investigation has proved that the greatest amount of amylase in a concentration has the most positive effect on the breakdown of starch, whereas the least amount of amylase has the opposite effect.