Preliminary work
For the experiment to investigate the effect of the enzyme catalse on hydrogen peroxide. First I tried an experiment to see what I would use, I tried carrot, potato and liver and found that liver was the most reactive but was too vigorous for this experiment, Carrot was the lest reactive and so wouldn’t be ideal for this experiment, so I chose to use potato which was reactive but not too much or too little. I also decided how much of the substances I would use I decided on 1cm³ of potato and 25cm³ of hydrogen Peroxide. I chose to leave each of the test tubes containing the potato and Hydrogen peroxide for 2mins.
Apparatus
For this experiment I will need:
15 cubes of potato
125cm³ of Hydrogen Peroxide
5 test tubes
5 pins
Test tube rack
Timer
Goggles
Measuring cylinder
Diagram
Method
Place 25cm³ of hydrogen Peroxide in each of the 5 test tubes.
Place 1 cube of potato on a pin and place into one of the test tubes
Start the timer as soon as you put it in the test tube
Record your result into a table and onto a graph
Place two cubes of potato on a pin and place into one of the test tubes
Start the timer
Record results
Place three cubes of potato onto a pin and place into one of the test tubes
Start timer
Record results
Place three cubes of potato onto a pin and place into one of the test tubes
Star timer
Record results
Place four cubes of potato onto a pin and place into one of the test tubes
Start timer
Record results
Place five cubes of potato onto a pin and put in one of the test tubes
Start timer
Record results
Make sure that all your cubes of potato come from the same potato or same kind of potato. Make sure that all of your Hydrogen peroxide is of the same concentration and that the room is at the same temperature for each one of it won’t be a fair test.
Obtain Evidence
Results table
Re-done results
I repeated my results to check that they were correct and that it was a fair test.
Analysis
From my graph I can see that I was correct with my predictions because the more potato added the larger the reaction until there was no longer any substrate to bind with the enzyme.
As the potato (enzyme) was added to the Hydrogen Peroxide (substrate) one or more polypeptide chains twisted and folded bringing together a small number of amino acids to form the active site (this is the location on the enzyme where the substrate binds and the reaction takes place). So when the products had been released the enzyme was then ready to bind with a new substrate until there was none left to bind with. The products produced when the enzyme and substrate bind so in this case potato and Hydrogen Peroxide bind together they produce water and oxygen this is what causes the bubbles.
Evaluation
My results weren’t accurate the first time but when I repeated them I had accurate results and had no anomalous results the second time. My results might not have been accurate the first time and I might have gotten anomalous results for a number of reasons. One of the reasons could have been the temperature because enzymes are made of protein and proteins denature in high temperatures. The enzyme activity speeds up due to the rise in temperature until an optimum temperature then when it rises above that temperature it denatures. Another reason for my results not being accurate could be due to the fact that a special cutter cut the potato and some of the corners would have been missing. It could have also been the fact that the Hydrogen Peroxide in one bottle was of a different concentrate to another one and that because the Hydrogen was left in the test tubes while we did each one separately it could have evaporated or heated up.
We could have made it a fairer test if we had cut the potato more accurately and so each piece would have been equal. We could have also made sure that the potato cubes were all from the same potato or the same kind of potato. We could have also made it fairer if the room temperature would have stayed the same this was difficult due to the fact we had a large number of people in our class at the time of the experiment. Also it would have been fairer if the Hydrogen Peroxide was of the same concentrate. It would have also been fairer if we would have had more time because it is easier to do if you aren’t rushing.
