Obtaining Evidence:
Test 1:
I will use 1ml of 0.2% starch solution and 1ml of amylase and time it first for 5 seconds and then add the iodine and record the results. I will then do the same again, but this time wait for 10 seconds before I put the iodine in and then record the results again. I will carry on doing this at 5 second intervals until I get a negative result.
Test2:
I will use 5mls of 0.2% starch solution and 1ml of amylase and time it first for 5 seconds and then add the iodine and record the results. I will then do the same as the first test except this time I will use 5mls of starch solution.
Method:
- Get 4 test tubes and place them in a test tube rack.
- Measure out 1ml of 0.2% starch solution.
- Measure out 1ml 0.1% of amylase.
- Get the iodine ready to put into the test tube.
- Put in the amylase.
- Get a stop watch and start it as soon as you put in the amylase.
- Time it for 5 seconds then add the iodine.
Do the same as what I put in my test 1 and 2.
Results Test 1:
Results Test 2:
As you can see from my table of results, the starch has been broken down after just 5 seconds so this is much too fast to record. This should not happen as it shouldn’t of been enough time for it to breakdown.
So if the starch is breaking down too quickly the enzyme could be overactive, working too well and maybe too concentrated.
Therefore, I have had to take secondary results. I have obtained some results from someone else using a different batch of amylase and their test has worked.
They have decided to change the concentration of amylase instead of the different amounts of starch. So they have done exactly the same as I did, but increased the concentration of amylase instead. They have also done 4 tests with different amounts of concentration of amylase and changed it to 10 second intervals. They have started with 0.025% and then went to 0.05% then 0.1% and then 0.2%
Prediction 2:
I predict that the more concentrated the amylase the quicker it will breakdown the starch solution and a quicker negative result when iodine is added. So therefore, I think that 0.2% will be the quickest. I believe this because when the amylase is more concentrated, it causes a higher rate of catalyse activity. There will also be more active places for a reaction to take place, which will cause more chemical reactions due to successful collisions because of the active site of the enzyme and substrate.
Results Test 1:
Results Test 2:
Results Test 3:
Results Test 4:
Overall Result in a Graph:
Analysing:
Conclusion:
The evidence from the results table and the graph I have drawn, obviously
shows that the more concentrated the amylase solution is, the quicker the starch is broken down, which will then give a negative result when iodine is added. The graph shows a steady slope downwards. It took 80 seconds for a 0.025% solution of amylase, it took 60 seconds for a 0.5% solution of amylase, it took 50 seconds for a 0.1% solution of amylase, it then took 20 seconds for a 0.2% solution. This shows that it is getting faster each time a more concentrated solution is added.
This supports my second prediction proving that the more concentrated the amylase solution is the faster there will be a reaction; this will break down the starch faster and change it into glucose. We know this because the iodine is a starch indicator showing that if starch is present then it will turn blue/black.
This has occurred this way because there is more amylase to work on the starch therefore speeding up the process and breaking down more of the starch at a time. The rate of reaction is directly proportional to the enzyme concentration when the substrate is in excess. This is due to the fact that when the enzyme concentration is raised it makes more active sites available to react with the substrate.
Information about Enzymes:
Amylase is found in 3 parts of the body: the salivary gland, the pancreas and the small intestine. Enzymes are crucial in our body otherwise we wouldn’t be able to absorb food into our blood stream: enzymes can help break down molecules which are too big to absorb to begin with. So the enzymes convert them into smaller molecules enabling them to diffuse through cell walls. When there are lots of nutrients, the molecules will diffuse into the blood with the help of active uptake because of the concentration gradient is the wrong way. They then travel to where they are needed in the body and then diffuse again.
An enzyme is a biological catalyst. They speed up the rate of a reaction however they are not affected themselves whilst doing this, this is why they are catalysts. Enzyme molecules have a very precise three-dimensional shape. This includes a 'dent', which is called the active site. It is exactly the right size and shape for enzyme's substrate to fit into (in the case of amylase this is starch). When a substrate molecule slots into the active site, the enzyme 'tweaks' the substrate molecule, pulling it out of shape and making it split into product molecules. Enzymes are made to be specific; this means that they can have only one substrate that they will work on. Each enzyme has an active site that is where their own specific substrate´s molecule will fit into. Amylase converts starch into simple sugars (glucose, maltose), proteases convert proteins into amino acids, and lipases convert fats into fatty acids and glycerol.
Enzymes all work best at an optimum temperature that is usually body temperature at 37°C. Most reactions work better at higher temperatures, this is because molecules move around much quicker. This makes the molecules have more chance to collide with the substrate. With more collisions there is more chance of a reaction taking place. This makes the rate of reaction faster. If the temperature that the enzyme has to work at gets too high, normally 40°C it will start to become denatured and therefore no longer work on its substrate as the active site has changed shape. By around 60°C the enzyme is completely destroyed. Also enzymes usually work best at an optimum pH level; this is normally 7 because enzymes are proteins which are damaged by very acidic or very alkaline conditions.
Evaluating Evidence:
This method can be inaccurate because when I first was given the amylase solution, it was warm and by the end of the experiments it had become a lot colder. This can affect the rate of reaction a great deal because a warmer temperature also will speed up the reaction process. But all in all, I still think this is sufficient evidence to show that the concentration of amylase has a big reaction on the process of breaking down the starch. It is clearly shown that the more concentrated the amylase solution is the quicker the reaction will take place. I have no anomalous results in the graph, there is a steady slope downwards.
We could have tested the temperature of the amylase with a thermometer before each experiment, making sure they were all the same.
With my first experiment it didn’t work properly because the amylase was overactive. I could have used a weaker concentration of amylase to slow the process down; this would have enabled me to get some negative results with the iodine indicator. So I would have a result for each different level of starch concentration. Then I would have been able to come to a conclusion from the results to say what affects there would be on the break down of starch with different concentration of starch solution.
To expand on my investigation I could find all the factors that affect the reaction of amylase on breaking down starch. I could do an investigation on different temperatures or the different pH affecting the rate of the reaction.
