Diagram:
Method:
- Measure off 10mm of hydrogen peroxide.
- Place 10mm of hydrogen peroxide into each 3 sets of 2 test tubes.
- Cut potato, carrot and apple up using cork and borer.
- Measure 1cm³ of potato, apple and carrot using a ruler and cut to appropriate level.
- Place 1cm³ potato into test tube and time for three minutes.
- After three minutes, measure the level of froth at the top of the first test tube( using a ruler), and do the same again in another test tube.
- Repeat the last two steps for each carrot and apple.
- Write down results and compare.
Results:
Analysis:
As you can see in both the graph and the table, potato has the fastest rate of reaction. We are now going to use the potato in the main experiment because its rate of reaction is ideal for measuring because the other two substances would be too small to measure. We were going to use liver in this experiment. However, we saw a video last week and we saw that the liver produces too much froth. It would produce so much froth that it would overflow the measuring cylinder that we are using. If it would overflow that would mean that we would not get a proper reading as we cannot measure it when it is on the work surface or over the edge. We then decided to use the potato because its level of reaction is one below that and is ideal. We could have done another trial to make sure that we eliminated any rogue results.
Conclusion
As we can see from our results, potato is the ideal substance for my main experiment. Its reactions were reactive enough to measure with ease. The amylase present in the potato reactions with hydrogen peroxide was far more than the carrots or the apples. Therefore, I am going to use potato in my main experiment.
Factors affecting the rate of enzyme action (main)
In my coursework I am investigating the rate of an enzyme action and what factors affect it. Enzymes are biological catalysts. They speed up the chemical reactions which go on inside living things. Without them the reactions would be so slow that life would grind life to a halt. The enzyme that we are going to use in the main experiment is called amylase. It is present in the following substances we used in the preliminary experiment:
- Carrots
- Pork( we didn’t use this substance due to the fact we already know its capabilities).
- Potato
- Liver. ( We didn’t use this substance due to the fact we already know its capabilities).
We saw these substances react with a certain level of pH of hydrogen peroxide. To see the results see “preliminary experiment”. However, in this experiment we are going to see the concentration of hydrogen peroxide. This is because we tested what kind of substance was added and we thought that it would be interesting to change the variable of pH.
Key Variables:
As I have already explained above, I am going to changes the variable of concentration. However, I will keep all of the other variables at a constant level:
- Temperature
- Stirring ( I will not stir any of the substance because it will be impossible to measure the amount of stirring, and so therefore will give rogue results)
- Substance (I will use the potato because it gave a level of froth that was at good level I could measure).
- Amount of substance (cm²)
- pH.
Prediction:
I predict that because hydrogen peroxide is being added to each test it will excite the catalase and make a faster rate of reaction.
Scientific Knowledge:
I know that the hydrogen peroxide will excite the catalase molecules further, therefore giving them more energy to have random collisions. The more random collisions there are, the faster the reaction will be. This will mean that there will be more oxygen produced which means more frothing (which is what I want to measure). Here is a graph below to explain my theory:
How I will carry out my investigation:
The enzyme I will use is catalase because it is present in all of the preliminary substances. I will measure the amount of frothing at the top of the measuring cylinder because that shows how much it has reacted.
Equipment:
- measuring cylinder
- potato
- hydrogen peroxide (20%-100%)
- Stop clock
- Measuring beaker
- Ruler
- Scalpel
- White tile
- Cork and borer.
The equipment I will need is set out as a diagram below (all labeled):
I will get my results by using a ruler to measure the amount of frothing at the top of the measuring cylinder (in cm’s). I will take three observations of each level of concentration of hydrogen peroxide (20%, 40%, 60%, 80%, and 100%).This rule out any rogue results. I will use the same amount of hydrogen peroxide as well. This makes sure that there is a balanced ratio between the amylase and the hydrogen peroxide. I will time each observation by 3 minutes. This will give adequate time for reactions to take place. To make sure that the reactions are fairly balanced I will use the same amount of potato. I will measure the potato in 1cm³, as this will be fair. I will have to work safely in this experiment because we are using hydrogen peroxide (an irritant to the eyes and the skin) I will use goggles. To make sure I am safe from harm I will:
- Stand up.
- Tuck in my chair.
- Remove loose clothing (i.e. blazer).
- Tuck in my shirt and tie.
To make sure that my investigation is a fair test I will not change of the variables only the one which I want to, which is to change the concentration of hydrogen peroxide.
Results
Analysis
In my experiment I could have done five trials to make sure that ach of the results we got weren’t rogue one’s. I could have made better time keeping in the level of froth. I should have kept strict time keeping. Also, my potato could have been cut better. The potato wasn’t cut exactly 1cm³. I should have done this because if I had done this, my results would be exact.
Conclusion
As we can see from my results the higher the concentration of hydrogen peroxide, the more froth is produced. This is because the amylase present in the potato reacts with hydrogen peroxide and reacts with the oxygen (which, in turn, causes frothing). The level of amylase present in potato is ideal because we can measure it with ease. The hydrogen peroxide gives energy to amylase molecules which makes them vibrate and get more collisions. This is what happens in a reaction.
Barrett Downing 4CP Miss Pascal, 4S2 Miss Noone
