Risk Assessment:
In this experiment there were not a lot of risk assessment that was dangerous to both my lab partner and I. The main risk assessments were to tie our hair back, we had to make sure that we didn’t spill any of the chemical on the floor has this could be dangerous.
Apparatus
To carry out this experiment, the following apparatus are needed:
- Trypsin
- Milk powder
- Standard laboratory glassware and apparatus
- Stop clock
- Colorimeter
- Thermometer
Reliability
To be reliable, measurements should also be accurate. To be accurate a measurement should be close to the true value. Precision involves the choice of apparatus and the skill with which it is used.
I had to also be aware of the different types of error that could occur in my experiment, systematic, random, and human errors. To overcome systematic problems I will need to know how to use apparatus correctly, to avoid human error I will have to give my full attention and concentration towards the experiment. To avoid random errors, I have to control changes in the material used or the conditions in which they are carried out in, as this will all affect the final result we produce.
Method
In this experiment, the rate of reaction is determined by the time taken for a given quantity of substrate to be used up:
1. Prepare trypsin solutions of different concentrations by mixing trypsin and distilled water together. Two syringes are used to measure and transfer different volumes of trypsin and distilled water separately. Label the test tubes:
2. Tap the bases of the test tubes to mix the enzyme-water solutions.
3. Use another syringe to measure 2cm3milk and transfer into each of the 5 test tubes. Start each stopwatch once milk is added into each test tube.
4. Tap the bases of the test tubes to mix the solutions.
5. Measure the time needed for the milk to turn clear in each test tube.
Variables
- The independent variable within this experiment is the concentration of the trypsin.
- The dependent variable within this experiment is the time taken for the milk to become clear
- The control variables of this experiment are the substrate (milk) concentration.
Conclusion
From my results I can see that the increase in concentration actually has a faster reaction of the enzyme and the casein so the more of this enzyme there is the faster this can be broken down and so the rate of digestion is directly proportional to the amount of concentration of enzyme there is i.e. the higher the concentration the faster the reaction and then the lower the concentration the slower the reactions are. In this case I can say that my hypothesis was right as I predicted that this would happen.
On the other hand, I could see an anomalous result that may not be that accurate. I can identify that there is a significant difference between some of the results, for example the 0.25% and 0.125% enzyme solution. The variance of this suggests that there is an error within the results. The reason for this error may be identified as error systematic error and random error. An example of systematic error is if the solution was made up incorrectly. For example too much enzyme may have been added and too water. Also, at 0 it took a longer time but the solution did not change.
Random error can also been the reason for the error within the result. An example of this is tiredness of the determining the end point of the solution. Also, as time was limited many of the recorded results may have been rushed. As a result of this, the accuracy of the results may have been affected.
To gain a more reliable result, more repeats should have been done and an overall average should have been worked out. Also other variable such as the concentration of the substrate i.e. the milk is to be kept constant and the temperature is also to be kept constant.
