Results
With the results I got I was able to draw a table, which displays the resembling colours of the starch and amylase solution reacting with the iodine and also displaying the times and any other relevant information.
Conclusion
From my preliminary work I was able to identify any problems I might have encountered and also I gained an insight into how amylase breaks down starch.. I noticed that the method I used in my preliminary work was not very reliable, accurate and would not be useful to use in the main experiment, as it would not give me accurate and reliable results. The main problems I identified were as follows;
- I was not able to get reliable and accurate results as I was adding drops of the amylase/starch solution every 30 seconds which means that the reaction turning the solution back to the original iodine solution could have taken place anywhere between 3 minutes and 3 minutes and thirty seconds.
- I was not able to control the temperature variable at all using the spotting tiles and this is important as the temperature affects the rate of reaction.
- I was not able to add precise drops using the graduated pipette at all times so the amount of liquid in each well might not have been the same as other wells.
However I did learn that the enzyme amylase was breaking down the substrate starch into maltose as the blue/black colour caused by the reaction between starch and iodine turned colourless as time progressed and the amylase began taking effect.
To overcome the problems I encountered during the preliminary experiment I will be using boiling tubes instead of spotting tiles as I will be able to clearly see the reaction take place as the tube is transparent, I will also be using a manual water bath to control the temperature of the amylase so that I have a fair and reliable set of results. I will also change the method I used in my preliminary experiment when I conduct my real experiment, as it was not very reliable or accurate.
Main Experiment
Prediction
By analysing my preliminary work and also using my own scientific knowledge I hypothesize that the starch concentration will definitely affect the rate of reaction and the time taken for the amylase to break down starch into products. I think that as the starch concentration is increased the time taken for the amylase to break down the starch will decrease as amylase acts as a catalyst. I predict this because as the concentration of starch is increased there are less water molecules so the chances of reactions are much higher than they would at low starch concentration. I also predict that as the starch concentration is increased so will the rate of reaction. This means that it will take the enzyme amylase less time to break down the substrate starch into sugar maltose.
By reviewing and analysing my prediction I can generate 2 graphs to show how
Apparatus
The apparatus that I will use to aid me in my experiment will be a;
Method
In order for me to be able to investigate the effect of starch concentration on an amylase controlled reaction I will follow a method for me to be able to efficiently and effectively conduct my investigation.
- Firstly I will measure 5 ml of 1% amylase into my 10ml measuring cylinder
- Secondly I will pour the measured amylase into one of my boiling tubes
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I will then place the boiling tube into a hot water bath and add a thermometer to the boiling tube to check whether the temperature is 30°C (to resemble body temperature).
- Fourthly I will measure 2 ml of 1% starch into my cleansed 10ml-measuring cylinder and then pour the starch into another one of my boiling tubes.
- I will then measure 8 ml of water using my washed 10ml measuring cylinder and add it to the boiling tube with the starch in it, making a starch concentration of 1%
- I will then add a few drops of iodine into the starch mixture, which will turn the solution to a blue/black colour.
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When the temperature of the amylase reaches 30°C I will take the boiling tube out of the hot water bath.
- Then I will place the blue/black starch solution into the test tube rack for ease and safety when adding the amylase to it.
- I will then add the amylase to the 1% starch concentration, and immediately start my digital stopwatch. I will stop the digital stopwatch when the amylase turns the starch colourless.
- I will then record my results in a table.
I will then wash my equipment thoroughly and repeat each concentration twice for accurate and reliable results.
I have made a dilution table, which I will follow to help me make the different concentrations.
Dilution Table
Fair Test
I will make sure that the experiment I conduct will be accurate and reliable by checking and modifying certain variables before I start my experiment.
Accuracy
In order to make sure that the experiment I conduct is accurate I will take certain things into account. I will make sure that I wash all of the used equipment thoroughly after each time I use it to ensure that the apparatus is clean and will not affect my final results. I will also check the temperature of the water bath regularly to check whether it is constant and not fluctuating. When timing the experiment I will use a digital stopwatch, which will give me extremely accurate results, which will help improve the accuracy of my experiment. Also when taking the measurements of the liquids I will read from the lower meniscus and also ensure that my eye is level with the reading. This will help to cut down on the margin of human error. I will make sure that I do not leave my experiment or any apparatus unattended at any time. All of these factors will ensure that my experiment is as accurate as it can be.
Reliability
I will make sure that my results are reliable by taking many things into account. As I have 6 different concentrations my results will be reliable, as they will spread out equally over a large range. The 6 concentrations will also help me to plot a better and more varied graph, which will help me in many ways. Also I will be repeating each concentration twice and working out an average time taken for the enzyme starch to break down the substrate starch. This will make my results even more reliable. Also as I have conducted preliminary work I will have an insight into the apparatus and how the reaction takes place so I will know what to expect and hopefully will not encounter any problems during my experiment.
Safety
During my investigation I will be using certain apparatus that may cause injuries to me or people around me so I will make sure that I am very cautious and safe. I will take certain precautions, for example I will make sure that I clear the work area so nothing is obstructing me, I will also remove any obstructions that are on the floor for example bags, I will make sure that I wear safety goggles at all times as the iodine solution is irritant. Also I will be very cautious when handling the hot water so I do not suffer from burns. As I will be using water to clean the used apparatus after I test each concentration twice, I will make sure not to spill any water on the floor as it could create a slipping hazard to myself and those around me. All of these precautions will ensure safety to me and those surrounding me throughout my investigation.
Results
By following my method and taking certain variables into consideration I was able to conduct my experiment successfully without any flaws or errors. The results of my experiment are as follows;
Analysis of Results
By analysing my table I can see that I have acquired a wide range of results for me to be able to analyse and also to draw 2 sufficient graphs. By repeating each concentration twice it has enabled me to spot out any anomalous results straight away. I have not encountered any anomalous results. I think this is due to the fact that I followed my method very well and also I had a sufficient amount of information of how amylase breaks down starch from my preliminary work.
By analysing my results I can also see that both of my predictions were correct. My prediction that - as the starch concentration increases the time taken for the enzyme amylase to break the substrate down into the simple sugar maltose, decreases is correct and also my prediction that - as the starch concentration increases so does the rate of reaction is correct. All of these factors evidently prove my prediction right. Also my graph predictions were also correct as visible by looking at my graphs.
I have attached 2 sheets of graphs; “Graph to show rate of reaction in comparison with starch concentration” and “Graph to show the relationship between starch concentration and time taken for amylase to break the starch down”. I will be able to analyse my results further by looking at my graphs.
Reliability of Results
By analysing my results I am able to judge whether the results I got from my main experiment are reliable or not.
As you can see my results from my 1st attempt and 2nd attempt are quite close to each other showing that they are reliable and are viable to be used.
Evaluation
To evaluate I believe that my experiment was conducted very well and the outcome was reliable and accurate results. However there is still room for improvement as my results can always be more accurate and reliable. I think if I were to repeat the experiment again I would definitely change certain factors so my results would benefit and be more accurate and reliable. The changes I would make are as follows;
- I would add a third attempt as well to get a wider range of data which will allow me to spot any anomalous results and improve the reliability of my results.
- I would increase the amount of starch concentrations I use and go up in 0.5’s till 5. This would definitely improve my results as I would have a wider range and also this would allow me to plot better graph as the more intervals I have the better the results are
- I would use an electronic thermometer instead of a manual one when I measure the temperature of the hot water bath. This would make my results more accurate and reliable because when I used the manual thermometer there was obviously a slight margin of human error.
- I would also ask a second person to assist me at times. For example when I am adding the amylase to the starch and starting the stopwatch. A second person would be able to start the stopwatch immediately whereas I had to try and pour the amylase into the starch and also at the same time try and start the stopwatch.
All of these improvements would increase the reliability and accuracy of my results ensuring a better outcome
Also I did not have any anomalous results as visible by looking at my graph.
Conclusion
In conclusion I personally think that the investigation was very successful. The predictions that I made proved to be right. I think that the reason my predictions proved to be right were partly because of the insight information I had received from the preliminary work I conducted, this helped me very much. Also my Introduction (see above) also led me to my prediction as I based it on the collision and lock and key theory. Also knowing about the properties of enzymes helped me to formulate a prediction. My results proved that as the concentration of starch increases the time taken for the amylase to brake down that starch decreases. It also proved that as the starch concentration increases the rate of reaction increases too
I also noticed that there is a positive correlation between the starch concentration and the rate of reaction. This is because as the starch concentration increases there are more successful collisions between the enzyme’s active sites and the starch particles creating more products. Enzymes are biological catalyst that speed up reaction.
I think that the graphs I drew were quite good as well as they displayed correlation of some sort which backs up the prediction of what my graphs would look like. I think that my graph would have been better if I would have had more points to plot.
To conclude I believe that the overall investigation was successful and I was able to investigate how starch concentration affects an amylase-controlled reaction. However I think that the experiment would have been better if the changes I pointed out in my Evaluation (see above) would be carried out.