Results:
Conclusion:
From this investigation I can see that my prediction was correct, and so the theory behind it must also be correct.
There is room for improvement in the investigation as well as extending it. There is many places were human error may occurred, affecting the results. The water bath did not keep a constant temperature, and some parts of the water bath were at different temperatures to other parts. The other thing that may have affected the experiment was the batch of the amylase solution and starch. This is because different batches are slightly different and if it is not from the same batch, slightly different results may be obtained.
This time I think I may investigate a different aspect of the investigation and if I use a water bath I will make sure the temperature I kept constant at all times, as a slight rise in the temperature may cause the enzyme to denature or not work as it should.
Factors which could affect the investigation and Why:
Temperature:
The temperature will affect the results of this investigation because heat passes on energy to the particles giving them kinetic energy, making them collide with each other more causing the reaction to occur quicker. However, enzymes work best at body temperature, and they denature, twist out of shape, at too high a temperature, about 60°C.
Volume of amylase and starch:
In a larger volume of a substance there will be more particles and so therefore more surface area for the reaction to take place. So if there was more amylase than starch, the reaction would be much quicker than if there was more starch than amylase. If the volumes are both equal I do not think that there would be any change in the rate of reaction, whether you have 10ml of each or 100ml of each.
Whether the amylase or starch is added first:
This will affect the investigation slightly because it is the amylase that reacts on the starch and breaks it down. So if the amylase was put in first it mite take a while for the amylase to react with the starch, but if the starch is added first and the amylase on top, as it is in the mouth, then it can get to work straight away.
Shape/size of containers used:
Depending on whether boiling tubes or test tubes are used may also affect the investigation. This is because with the test tube being thinner, it may confine the particles and prevent them from mixing and moving around as freely as they might be able to in a boiling tube, which is thicker than a test tube. The starch and amylase will also heat up quicker in a boiling tube than a test tube as they are nearer the heat source.
Whether the equipment is clean:
The equipment needs to checked at the beginning of the investigation because if there have been any other chemicals in the boiling tubes or the beaker, we will not get the correct results.
Key Factor to be Investigated:
Concentration of the Amylase:
The concentration of the amylase will affect the investigation because, as with everything, it is at its strongest when it has not been diluted. In a more concentrated solution, all the particles are parts of the enzyme amylase, but in a more dilute solution some of the particles in the solution will be water molecules as this is what we diluted the amylase with.
Prediction and Theory:
I predict that as the concentration of the amylase decreases then the rate of reaction will increase. I predict this for the reason being that as the solution is getting weaker, more dilute, there are less particles of amylase in the solution. This means that for every particle of amylase there are more molecules of starch to be broken down into glucose every time the amylase solution is diluted. I have explained thins in the diagrams below:
From this prediction I can say that I think the results will be linear and the time will get faster the more concentration there is. After I have collated the results from this experiment I will also find out the rate of reaction, and be drawing a 1/t graph. I think the graph for the average time, and the graph for the rate of reaction will look like this.
A graph showing the average time. A graph showing the rate of reaction.
Rate of Rate of
Reaction Reaction
Concentration Concentration
Fair Test:
It is extremely important, as with every investigation that everything is kept fair. This means that all the things that could affect the outcome of the investigation if they were changed, needs to be kept the same and only the variable is to be altered. In this case the variable is the concentration of the amylase solution. The things that need to be kept constant are; the temperature, the volume of the two solutions, the way in which the amylase and starch are put into the third boiling tube and whether a boiling tube or test tube is used. Other things like making sure the boiling tubes are clean and they are not mixed up needs to be checked as this will make the test unfair and void.
Apparatus:
- Tripod,
- Gauze,
- 1 Glass Beaker, (250ml)
- 2 Small Glass Beakers, (100ml)
- 2 Cylinders, (scale 1ml - 10ml)
- Test tube rack,
- 3 Boiling Tubes,
- Pipette,
- Bunsen Burner,
- Heat Proof Mat,
- Goggles,
- Acid Gloves, (for sensitive skin).
Materials:
- Starch Solution, (10ml)
- Amylase Solution, (10ml)
- Iodine
- Water, (to create water bath).
Diagram:
A S
Iodine
Safety:
Safety is one of the key things in every experiment. As we are using a bunsen burner, goggles need to be worn at all times and a heat proof mat needs to be used. These will protect the bench and our eyes. Long hair must be tied back and out of the way and the safety flame needs to on when we are not using the bunsen to heat up the water bath. All the equipment should be checked to make sure there are not faults. The gas must be turned off as soon as we do not need the Bunsen any more.
Method:
- The apparatus and the materials were checked to make sure that they were all clean so that we could rule out the possibility of the apparatus producing anomalous results.
- The tripod, gauze, bunsen burner, heat proof mat and beaker were all set up as shown in the diagram.
-
The water was heated to 40°C to act like a water bath and kept at a constant temperature. The starch solution and the amylase solution were measured out, in separate measuring cylinders and put into separate boiling tubes and put in the water bath for 5 minutes.
- After 5 minutes the starch solution is poured into a clean boiling tube with the amylase solution poured on top. A couple of drops of iodine are added, making the solution turn a bluey-black and the boiling tube is returned to the water bath and the timer is started.
- When the bluey-black solution has turned clear stop the timer and record the time.
- Repeat the investigation with the different concentration of amylase recorded the time taken for the starch to turn into glucose each time. To dilute the amylase to 80%, 60%, 40% and 20%, put 8 ml, 6ml, 4ml, or 2ml of amylase solution into a measuring cylinder depending on the concentration of the amylase wanted, and then fill the cylinder up to 10ml with water.
- Repeat the whole investigation twice more, so an average can be taken.
Results:
From these results I am now going to draw a couple of graphs, one showing the average time against the concentration and the other showing the rate of reaction against the concentration. These will show the above information in a different and perhaps clearer way than the table above. The will also show whether there is any correlation between the rate of reaction and concentration and if there is any correlation between the time the reaction takes and the concentration, i.e. if concentration does affect the results in a pattern, following a rule.
Graphs:
Shown on the next few pages.
Conclusion:
From doing this experiment I have been able to come to the conclusion that the concentration of the amylase clearly does have an affect on the experiment. My prediction that I made before the experiment was carried out turned out to be correct and so I can therefore conclude that the theory behind my prediction is also correct. The graph shape that I predicted earlier is also correct, again confirming that the theory behind my prediction was accurate. I feel that this helps to show that the theory is right if I predicted the outcome before hand because there was nothing else that led me to my prediction that I made.
Evaluation of Results and Graphs:
The results that we finally achieved are pretty accurate. I can say this because we compared our results with peers from another group also doing this investigation and as each of our final set gave us more or less the same times I can again conclude that the results are accurate. The experiments that went wrong did not give us any results and so I cannot evaluate these.
The graphs show what I thought would happen. The graph showing the rate of reaction has a positive correlation and the graph showing the time taken for the reaction has a negative correlation. As they have correlation, it proves that the concentration of the amylase does affect the results of this experiment between amylase and starch. The higher the time taken, the lower the rate of reaction. This simple sentence explains the shapes of the graphs and why there is a change in correlation in the two graphs.
Evaluation of Procedures:
The investigation did not go very smoothly as first the first couple of weeks the experiment would not work out the way it should. We knew the kind of results that we were looking for and so this is how we knew that there was something wrong. It was either the amylase or the starch or the iodine was not quite right. We knew that it was not human error as our group was monitored very closely when we had not got any results after the first couple of weeks. We were advised to do it, when we had run out of time at a lunch time because the amylase and/or starch were maybe too warm to work with in the morning, so this is what we did. The experiment with many trials and errors finally worked and we got our results. To ensure that we did get them all we had to work individually, so to get all the experiments, for at least one set of results in a lunchtime.
Making our own water bath and keeping it constant was a difficult task at the beginning, as the temperature of our water bath, at the beginning kept either rising above, or falling below 40ºC. This may have caused faults in our experiment but as the temperature of the water bath never reached over 60ºC, where as we have seen in past experiments the enzyme denatures, we felt that it should have only affected our results and not the enzyme. This made us think that the amylase solution was not quite right when we were using it.
Despite this, I fell that we worked well as a team, even under pressure and we followed all the safety requirements and made sure all the tests were as fair as we could make them.
If I were to repeat this experiment there would be a few things that I would change. The water bath was one of our main fall downs and so next time I would either use a temperature probe to monitor the temperature, or use the water bath, which is maybe not as reliable as it sounds as I found out in previous experiments. I would make sure that I had enough time to do the whole experiment three times in one session, so that the amylase and starch is from the same batch and I would also do it in the afternoon when the amylase and starch had had time to settle.
