The Variables
Controlled
The controlled variables are the things that I must keep the same to keep the experiment fair. In this experiment I will have to keep the amount of substrate the same, amount of amylase the same, my timing apparatus and heating apparatus. Even though the last two wouldn’t seem to matter, for a fair test they must be kept the same.
Independent
This is the one thing in an experiment that I can allow to change to keep the experiment a fair test. In this experiment it will be the temperature. I will measure in minutes. Ill be measuring how long it takes for the starch to be broken down be the enzyme.
In this experiment I will take readings at 6 different temperatures. I can then look at the class results to use as repeats, use to average my results and to see if any of my results were too far out, possibly meaning an anomaly. I will be using 3 sets of results to improve reliability. After I have got my results I can then look back and see if I can prove my prediction.
Method
Apparatus:
- Thermometer
- Glass rod
- Test-tube rack
- Spotting tile
- Stop watch
- Beaker
- Tripod
- Measuring cylinder
- Tripod
- Gauze
- Bunsen burner
- Boiling tube X 2
Safety
During all experiment you should try to be as safe as possible and not fool around. In this experiment you should wear goggles to protect you eyes and you should not allow the water bath to boil over as is dangerous as this could cause burns.
Course of action
- Collect apparatus
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Heat 200cm3 of water to the first temperature, or use a water bath. The water has to be at the constant temperature or this could alter your results.
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Measure 5cm3 of starch using burette or measuring cylinder.
- Put the starch in a boiling tube
-
Measure out 5cm3 of amylase and add to separate boiling tube
- Place both boiling tubes in the water bath for 1 minute
- While waiting place a drop of iodine to each spot on the spotting tile
- As soon as a minute is up mix the amylase with the starch in one of the boiling tubes then place back in the water bath.
- Take a sample using a glass rod by dipping it in the mixture then into a spot with a drop of iodine. The iodine should change to black/blue, showing that starch is present.
- Keep taking a sample every minute until the iodine doesn’t change colour or there is no breakdown as the amylase have become denatured.
- Record time on a table of results
- Repeat all for each temperature
Results
From my results I can see that the optimum temperature was around 50oC. I will also use my classes results to act as retests and average 3 tests for a average table and graph.
The table will include my results with 3 retests and an average.
These are my results with my three retests. For my first graph I will plot my results, but before I do I will need to change them by putting the time under 1 then multiplying by a factor of ten as this will allow me to get Arbitrary Units. This will help me see the relation between rate of reaction and the time.
Conclusion and Evaluation
In conclusion I can see that when temperature is increased to the optimum temperature for an enzyme the rate of reaction increases but after the threshold of the optimum temperature has been passed the rate decreases as time increases. This supports my hypothesis that enzyme activity will peak at a point (optimum temperature) then decrease, although the temperature range that I showed didn’t seem to be hot enough for the enzyme to become denatured. Since the optimum temperature of this enzyme was around 500C I can say that this isn’t an enzyme in the human body as the human enzymes would have an optimum temperature of around 370C because that is the temperature the human body stays. There for the enzyme I test wouldn’t be effective in the human body.
If I was to do the experiment again I would try to use a more accurate way of keeping the water at the exact temperature as this could be a factor that could cause anomalies.
I believe that my results turned out very well, I don’t believe my results were out to much and they seemed to co-incite with the rest of the classes results which I used some for retests.
