Likewise, the variable affects the reaction in the exact same as that with the starch concentration. (I will be using 1ml amylase enzyme)
To identify how this variable affects the rate of the amylase-starch reaction, knowledge of the states of matter must be incorporated.
A liquid would react faster then a solid, this is because there are fewer bonds in the liquid than the solid and so the particles would be more be more free particles and so will be moving more frequently than a solid. If the particles are moving more frequently than the chances of collision are increased. If the chance of a collision increases, then the chances of an effective collision increase, hence, a greater rate of reaction. (I will be using starch in a liquid form)
Obviously this is a variable that is common to all reactions; this variable must be kept the same in order to sustain a fair test.
Safety Precautions:
For both Preliminary and Official experiments
When I carry out my investigation I will have to take under consideration some safety precautions. These safety precautions are very vital, because if I don’t take these simple measures in mind then there would be serious danger, not only to my self but also to my other classmates.
- I must wear safety goggles to protect my eyes from irritant chemicals such as Iodine.
- I must also ensure that I handle the enzyme with care as they are biologically active proteins which may show some affects.
- I must keep my stool under the bench at all times. The stool will obstruct the pathway and this can prove to be fatal. If this is not carried out, a person passing by may trip over the stool whilst he is holding a piece of equipment or a substance, which may endanger him.
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I must put maximum effort into assuring that care will be taken with the hot water at all times and in making sure I do not spill it. This is such as the kettle boils the water and I have no other choice but to collect it from there. It’s therefore advised to wear gloves even though the beaker has insulation as some hot water could possibly spill in the event of an accident. Thus I must be careful when handling it and not to endanger any individual.
- I must not communicate with any other classmate except from the colleagues of whom I’m working with;
- I must keep my bag in the cupboard, so that it is not a potential hazard in the pathway.
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I must always concentrate in the job I’m doing. Carelessness will occur when trying to carry out more than one activity.
- I must be careful when I’m working and not put any ones life at risk.
Fair Testing:
This is when the result is only related to the variable being tested.
For example, if there are 7 variables, six variables must be kept identically the same and only one is changed/tested to see how this affects the outcome. This is ensuring that this investigation shall only be testing one variable (Key Variable). I have listed the variables below and the key variable.
Fair Testing: (This applies for both Preliminary and the official experiments)
A variable is something, which can be measured or controlled. A dependant variable is the variable you must keep identically the same. I must only test one variable at a time. The independent variable is the one I alter/test. These are my variables:
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Temperature [Independent Variable] (As this is the Variable I’m testing. I will therefore change the temperature accordingly with my experiment);
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Ph of solution [Dependant Variable] (This is a variable which I am not altering. Thus, I must not make any amends to the Ph when repeating the experiment);
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Concentration of Enzyme [Dependent Variable] (This as well is not a variable that I’m testing. Though I must put special effort into assuring that the concentration of enzyme remains uniform throughput the experiment i.e. using the correct quantity of Enzyme. As this can indeed affect the outcome greatly);
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Concentration of Starch [Dependant Variable]
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Starch and the state of Starch [solid/liquid] [Dependant Variable] (This is a very significant variable. Obviously if the starch was at a liquid state then the reaction will be faster then that of which if the starch was in a solid state. Therefore, to obtain a fair test when repeating the experiment more then once it is essential to keep the type of starch the same and more importantly at the same state;
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Time [Dependant Variable] (time is crucial in this reaction. When doing the experiment more then once, the amount of time before each test must be uniform to obtain fair results);
- Key variable (Independent Variable)
This is the variable, which is the most important to the activities outcome. This will always be that changes. My key variable is Temperature.
In order to obtain the best results, it’s essential to acquire the most accurate results possible. Therefore, in both the preliminary and official experiments the practical was repeated at least twice and then averaged. If by chance the two results are very different then it must be done a third time to confirm which is a human error. Then merely ignore the faulty value and average the two, which are similar. Nevertheless, I have chosen to repeat it three times to be on the safe side and to attain the best possible results.
Apparatus Required:
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Test Tube: I will need a Test tube to mix together the starch and amylase solution.
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Kettle: I’ll be using a kettle to boil the water I need. (Care must be taken when handling this)
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Beakers (X3): One of the beakers will have a polystyrene layer of insulation; this will be the beaker where the starch-amylase (solution mixed in a test tube) is put in. It is wrapped with a layer of insulation which is necessary to help the allocated temperature maintain and not decline. One other beaker will have cold water and the last will contain hot water. This is simply needed to maintain the temperature and so If it was to decline then hot water would be added to restore back the temperature and vice versa. It is for this reason that the beaker is filled with ¼ of its capacity and so when adding more hot or cold water to either increase or decrease the temperature it will not overflow.
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1 Spotting Tile plate: (12 hollow spots) Contained in each of the hollow spots is one drop of iodine which is essential for the testing of the amylase-starch.
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Glass Rod: This will be used for the purposes of testing. The glass rod will be first dipped into the test tube (which is in the beaker set at the allocated temperature) and then will be touched on a drop of iodine (in the hollow spot).
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Thermometer: This is placed inside the water beaker to make sure the temperature is maintained.
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Stopwatch: A stopwatch is needed to time a repeated interval between every 15 seconds. This is because I will be testing the amylase-starch solution every 15 seconds. I must therefore use a stopwatch for the purpose of good accuracy.
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5ml Starch Solution (1%): 5ml of this solution will be needed, before I mix this with the amylase in the test tube I must heat it up in the beaker to attain the same temperature.
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100ml Measuring Cylinder: This piece of apparatus will be used to measure the 5ml of starch. I will ensure that each measurement will be at eye level to ensure a fair test throughout.
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1ml Bacterial Amylase (3%): This will be measured using a syringe. It will be sealed with blue tack for fair testing purposes.
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Iodine: This will be needed for the testing of the amylase-starch. One drop should be put into each hollow spot. No more and no less, again for the purposes of fair testing.
Method:
Procedure to conduct the Amylase-Starch Experiment
- 1.) Firstly I will be required to read-through and understand the safety procedures, needed to be implemented throughout the experiment.
- 2.) I will then gather all equipment necessary for the experiment.
- 3.) I will measure out 5ml of starch solution using a measuring cylinder and place into a test tube in a test tube rack. (The measuring will be done at eye level throughout each of the three tests to ensure a fair test)
- 4.) I will then measure out 1ml of Amylase solution using a syringe, then seal the syringe with a blue tack to prevent loss of starch. (As with the starch, this will also be done at eye level for the same key reason)
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5.) My next step will be to prepare the site for testing i.e. the spotting tile. I will be adding one drop of iodine solution to each of 12 hollows in the spotting tile. (I must make sure this one drop is to equal proportion throughout, for the purposes of fair testing)
- 6.) I will then prepare to boil water using a kettle (I must ensure to apply all safety procedures as this can result in some accidents). I shall then fill ¼ of an insulated beaker with the boiling water. With the second beaker I shall add some spare boiling water and with the last beaker I shall fill with cold water. The need to only fill ¼ of the insulated beaker was explained in the apparatus.
- 7.) When the desired temperature of the water is reached I will insert the amylase enzyme into the starch (in the test tube). I will Fit on a rubber bang and shake carefully for a few moments.
- 8.) Following that I will Place the amylase/starch test tube into beaker (which has been maintained with the allocated temperature) and allow 15 seconds for the mixture to reach the temperature of water (in the beaker).
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9.) After that, I will begin the time and test process. I will time a repeated duration of 15 seconds and test during each interval. Testing requires the procedure “DIP-TEST-RINSE-WIPE” i.e. using a glass rod to dip into the test tube then touch the iodine on the spotting tiles. Finally rinse in some water and wipe with a paper towel.
- 10.) Repeat step 9 every 15 seconds until the colour of the iodine in the hollow does NOT change colour. The colour will be brown when no starch is present (the colour of the iodine is blue/black)
- I will finally note down the time it takes. This is will be the time taken for the reaction to be completed.
This method is applied to each individual temperature, and for the purposes of very good accuracy, I have decided to repeat each temperature 3 times and average the values.
Diagram:
In the above method I described how to conduct the experiment step by step. Here are just some diagrams to reinforce understanding of conducting the experiment successfully.
Obviously these diagrams are of the essentials in the practical. The remaining Apparatus must be used either as minor peripherals, or in setting up.
Once my equipment was set up, I used it in a safe way to obtain my results. I carried out the safety procedures, which I stated before.
When I carried out the investigation I made sure that I had enough results, so I would be able to conclude my findings. As I stated in my ‘Reliability of Evidence’ to obtain accurate results I took three readings and averaged the results. If one of the results proved to be very different from the other two, this can be identified as human error and so will be eliminated before taking the average of the remaining two.
The main instrument/measuring utility used to obtain precise evidence was a thermometer. It was used to maintain the temperature of the water in the beaker. A stopwatch was used to identify the times for testing i.e. every 15-seconds. Care was taken to ensure that it did not elapse the 15-second mark and so was called out to test at 14s and so to give time for the movement from the test tube to the spotting tile for testing.
Results:
These are my results I obtained for my preliminary experiment (first trial run):
[(Test 1 + Test 2 + Test 3) / 3 = AVERAGE]
As mentioned before, for the purposes of good accuracy I repeated the experiment three times, and took an average as my final result. Thus, I will only be analyzing the Average results.
Results #1:
Results #2:
Results #3:
I compiled the following graph from the average results:
My results were declared faulty after the temperature of 75°C as can be seen from the table of results and the graph. The results below and including 75°C are said to be ‘okay’.
Analysis:
Even though my results were declared faulty, I will analyse the results that I achieved successfully.
I predicted in my hypothesis that the optimum temperature would be at around 45°C. Though from only looking at the correct results I have, it shows that the as the temperature increases from 45°C - 75°C the time taken for the starch to be broken down by the amylase decreases from 535s (8.92 minutes) – 100s (1.6 minutes). The time of 100s was the fastest observed and so the 45°C temperature proves to be the Optimum Temperature (column in the table highlighted GREEN)
The Optimum Temperature is the temperature where the amylase functions most rapidly.
My Prediction of 45°C for the optimum temperature was due to my knowledge of enzyme and particularly the amylase enzyme. In school and dependably elsewhere I learned that most enzyme function between 30-50°C and denature at about 60-70°C. Though I did not realise that a BACTERIAL amylase enzyme acts differently to the amylase enzyme present in the human body. And so I wasn’t aware that it would have a different optimum temperature.
Beyond the temperature of 75°C I did not achieve correct results of which I gave the possible reason in the evaluation.
At a temperature of 80°C - 90°C my results show a time of 0s, simply meaning that the enzyme must be denatured (ceased to function) (the brown iodine turns blue/black at the start of testing and does not turn the iodine brown).
I do know that this is not correct as an enzyme apparently does not denature that fast i.e. 5°C above the optimum temperature. An enzyme goes through a series of changing before it is completely denatured. The structure of its active site jostles and reforms and gradually reaches a point where its active site has changed so much that the ‘key and lock theory’ does not apply i.e. the substrate ‘key’ no longer fits into the structure of the active site ‘lock’.
I have made a graph showing the rate of reaction in the experiment (this is only done for the correct temperatures between 45°C-75°C. The remaining temperatures between 80°C-90°C are incorrect and so I have not included them in.
The rate of reaction graph is simply done as a 1/Time graph.
1/Time Results: (Answers taken to four decimal places)
Conclusion:
I stated in my prediction the following:
“Increasing the temperature will increase the rate of reaction between the enzyme and the substrate accordingly. However, I am aware that the temperature can only be increased or decreased to a certain point before the reaction corrupts as the enzyme will cease to function. I believe that this will occur above 45°C.”
As I explained before, my prediction of 45°C optimum temperature did not turn out as expected. Likewise, I explained that my prediction was based on my understanding from school research on the amylase enzymes and did not bear in my mind that a BACTERIAL Amylase enzyme functions differently.
Though I did make some progress in my preliminary experiment as I achieved the results in the range of 40°C-75°C correct. Unfortunately, I do not think I can base a conclusion on this alone as I do not know what could have happen after this temperature. For example from the correct results I achieved, 75°C proves to be the optimum temperature with the starch being completely digested at 100s. However, I do not know what it would be like after 75°C, as 78°C or 80°C could prove to digest the starch much faster and so be the optimum temperature.
Though in the more general view, in the correct section of my results it evidently proves that when increasing the temperature, the rate of reaction between the amylase enzyme and starch increases. The reaction will increase to an optimum before declining again. Though, I cannot prove this to be correct as my investigation does not to reach that stage whilst results are valid.
Using scientific knowledge to back up the conclusion achieved from the results:
When temperature or thermal energy is transferred to a substance it will cause more movement (In a solid will cause more vibration until enough bonds broken to form a liquid. In a liquid will cause much for movements and the remaining few bonds will be broken eventually forming a gas. In a gas this will cause faster random movement). When the thermal energy is transferred to the starch and amylase molecules (liquid state) it will cause much more collisions. Reactants need collisions to react. Hence, more collision will ultimately cause a faster rate of reaction. The optimum temperature (when looking so far at the correct results shows its 75°C) is a point that identifies where the enzyme works most rapidly. Where the enzyme works most rapidly then the rate of reaction will be greater.
I hope to achieve a successful outcome in my official experiment and to examine if 75°C proves to be the optimum or not. I will also need to obtain the correct decline in rate of reaction after the optimum to prove the theory correct.
Evaluating:
As already stated above, I am not pleased with my results as they were proven faulty above the temperature of 75°C.
When testing with the brown iodine at the temperatures of 80°C, 85°C and 90°C, the colour of the iodine turned blue/black and so meaning that the enzyme must not be functioning (starch is still present; it’s not being digested)–and so must be denatured. This proves that starch is present. If the starch was not present then the colour of the iodine would be brown. Gradually as the starch is digested the colour of the iodine when testing progresses from blue/black to brown. I believe that there must have been a fault in the iodine as the tests repeatedly showed no change in colour.
I also believe I need rid the use of water beakers and the need to constantly add hot or cold water just to maintain the wanted temperature. This is very annoying and time consuming and deprives me of concentrating on the precision of my testing and conducting the experiment on the whole.
For my official experiment I must think of ways to encounter this problem as I do not believe I will succeed in obtaining a successful outcome when using this unreliable method of using water beakers. I must think of ways to improve my technique and apparatus to obtain precise and reliable results.
I have begun to prepare for my official experiment, and my initial idea in changing the apparatus is replacing the water beaker method with using a water bath. This apparatus can dispose of the constant tendency to mind the temperature; and will make the experiment a lot easier. It will rid of all the complications such as overflows and the increase/decrease of the temperature in the beaker. The water bath will be reliable in keeping the temperature constant automatically and so put me very close to achieving correct results and hopefully a good conclusion. This essential apparatus will also benefit me in putting more concentration on the precise timing of each necessary test.
On the whole, I believe my method was acceptable even though my apparatus was extremely poor. Nothing dangerous or disastrous occurred because I carried out my investigation according to my safety procedures. I will make the above alteration in my apparatus and more generally in my method to ensure I will gain successful results in the official experiment.
Aim: ‘Investigating how temperature affects the rate action of the amylase enzyme on starch.’
Having done my Preliminary experiment, I will be now doing the Official experiment. I have identified the major areas to be improved in the preliminary experiment mainly as the results were declared faulty. In this second part of the write-up I have only written about the major areas with differences and left out work that was not changed.
Official Prediction due to results from the Preliminary:
Having done the preliminary experiment (where the results where declared faulty) I have noticed that as the temperature is increased the rate of the amylase-starch reaction increases. However, the temperature increases the rate of reaction only up to a certain point whilst still proving to be beneficial. Above the temperature of 75°C I believe the rate of reaction will begin to decrease until the enzyme denatures.
Explaining Prediction:
This was something I picked up from the preliminary experiment. In the preliminary hypothesis I stated “I am aware that the temperature can only be increased or decreased to a certain point before the reaction corrupts as the enzyme will cease to function. I believe that this will occur at about 45°C.”
This hypothesise that I stated in the prelim was due to my knowledge on general enzymes. In the essential background reading I researched about the amylase enzyme and found out that the optimum temperature was ranging from 30-50 where 45°C proved to be the best optimum temperature. Though the enzyme we investigated was a bacterial amylase enzyme and so I found out that it acted differently in the prelim. My preliminary results were correct enough to observe this optimum temperature.
I will significantly change my apparatus and the method of conducting the experiment to obtain more precise results.
In this official investigation, I will look to see if I can observe a more accurate optimum temperature and the correct downfall of the rate of reaction after the optimum (unlike the preliminary results).
Apparatus required:
(Due to the poor result outcome I have changed a piece of apparatus that will enable me to obtain accurate results)
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Test Tube: I will need a Test tube to mix together the starch and amylase solution.
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Water Bath: A water bath to this investigation is an essential piece of apparatus, of which I chose to use due to the faults in the preliminary experiment. The water bath works by pouring water into the water bath and manually adjusting to a temperature between the ranges of 30°C - 100°C. The Temperature is automatically maintained.
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1 Spotting Tile plate: (12 hollow spots) Contained in each of the hollow spots there is one drop of iodine which is essential for the testing of the amylase-starch.
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Glass Rod: This will be used for the purposes of testing. The glass rod will be first dipped into the test tube (which is in the water bath) and then will be touched on a drop of iodine (in the hollow spot).
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Thermometer: The thermometer is not necessary as the water bath can automatically adjust to a desired temperature. Though I will keep the thermometer in the water bath to be on the safe side.
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Stopwatch: A stopwatch is needed to time a repeated interval between every 15 seconds. This is because I will be testing the amylase-starch solution every 15 seconds. I must therefore use a stopwatch for the purpose of good accuracy.
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5ml Starch Solution (1%): 5ml of this solution will be needed, before I mix this with the amylase in the test tube I must heat it up in the beaker to attain the same temperature.
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100ml Measuring Cylinder: This piece of apparatus will be used to measure the 5ml of starch. I will ensure that each measurement will be at eye level to ensure a fair test throughout.
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1ml Bacterial Amylase (3%): This will be measured using a syringe. It will be sealed with blue tack for fair testing purposes.
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Iodine: This will be needed for the testing of the amylase-starch. One drop should be put into each hollow spot. No more and no less, again for the purposes of fair testing.
Method:
Having done the preliminary experiment, I identified the major problems and so changed the method (e.g. use of water bath)
- 1.) Firstly I will be required to read-through and understand the safety procedures, needed to be implemented throughout the experiment.
- 2.) I will then gather all equipment necessary for the experiment.
- 3.) I will measure out 5ml of starch solution using a measuring cylinder and place into a test tube in a test tube rack. (The measuring will be done at eye level throughout each of the three tests to ensure a fair test)
- 6.) I will then measure out 1ml of Amylase solution using a syringe, then seal the syringe with a blue tack to prevent loss of starch. (As with the starch, this will also be done at eye level for the same key reason)
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4.) My next step will be to prepare the site for testing i.e. the spotting tile. I will be adding one drop of iodine solution to each of 12 hollows in the spotting tile. (I must make sure this one drop is to equal proportion throughout, for the purposes of fair testing)
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3.) I will then fill a water bath with water and set it to the temperature I require (Instead of the ‘absurd’ way of trying to maintain a temperature with beakers of water [which is highly destined for errors] I have decided to use a water bath which is a very accurate and reliable apparatus.
- 7.) When the desired temperature of the water is reached insert amylase enzyme into the starch (in the test tube). Fit on a rubber bang and shake carefully for a few moments.
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8.) Following that I will Place the amylase/starch test tube into the water bath (which is maintained at the desired temperature) and allow 15 seconds for the mixture to reach the temperature of water in the water bath.
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9.) After that, I will begin the time and test process. I will time a repeated duration of 15 seconds and test during each interval. Testing requires the procedure “DIP-TEST-RINSE-WIPE” i.e. using a glass rod to dip into the test tube then touch the iodine on the spotting tiles. Finally rinse in some water and wipe with a paper towel.
- 10.) Repeat step 9 every 15 seconds until the colour of the iodine in the hollow does NOT change colour. The colour will be brown when no starch is present (the colour of the iodine is blue/black)
- I will finally note down the time it takes. This is will be the time taken for the reaction to be completed. I will be doing each
This method is applied to each individual temperature, and for the purposes of very good accuracy, I have decided to repeat each temperature 3 times and average the values.
Diagram:
In the above method I described how to conduct the experiment step by step. Here are just some diagrams to reinforce understanding of conducting the experiment successfully.
Obviously these diagrams are of the essentials in the practical. The remaining Apparatus must be used either as minor peripherals, or in setting up.
>Why my plan is a good way of carrying out the investigation:
Using my scientific knowledge, I think my plan is a good way of carrying out the investigation because I have taken into account all the important factors. I have made sure that I have made my investigation as fair as possible. By controlling my variables I have made sure that I have kept all the variables identically the same except for the independent variable which is tested/changed (this independent variable is temperature)
I have made sure that the experiment is as safe as possible. This is very crucial because safety comes first. I would be putting the lives of my colleagues at great risk and danger if I were to be working in conditions, which were not safe. I have taken into account reliability of evidence by repeating the task. I will test my key variable 3 times and then average the values. This will rule out any possible chance of human error, and give me much more accurate results.
>Describing how earlier work helped my planning:
I learnt that accuracy was a key issue in my investigation and so had to change my apparatus and method significantly. Unlike the preliminary experiment I will be using a water bath. This will always keep the temperature of the water at one allocated temperature and will greatly increase accuracy.
Beforehand, in the preliminary experiment it was extremely difficult (seemed impossible!) to keep the temperature steady at one value. As the temperature decreased I had to add more hot water into the beaker, but almost always after doing so, the temperature would increase beyond the temperature I was testing. Therefore I had to add cold water to decrease it back! This often resulted in the beaker overflowing. The temperature continuously was either going above or below the wanted temperature. It was surely a very bad and unreliable way to conduct the experiment-and the results proved it so!
Due to the preliminary experiment I have altered my planning and believe it to be successful. By using the Water path, I believe I have increased the chances of obtaining better and more reliable accurate results. I have also but a lot of hassle off. I will not require a constant reserve of hot and cold water as the water bath will keep the temperature constant. I will therefore put maximum effort in assuring that the experiment runs smoothly and keep my concentration on the timing and taking results.
Once my equipment was set up, I used it in a safe way to obtain my results. I carried out the safety procedures, which I stated before.
When I carried out the investigation I made sure that I had enough results, so I would be able to conclude my findings. As I stated in my ‘Reliability of Evidence’ (this was written in the preliminary section) to obtain accurate results I took three readings and averaged the results. If one of the results proved to be very different from the other two, I identified it as human error and so I eliminated it before taking the average of the remaining two.
=>Instruments that helped to obtain precise Evidence
As I am now using a water-bath, it was no longer necessary to have a thermometer, though I did pop it into the water just to be on the safe side. A stopwatch was used to identify the times for testing i.e. every 15-seconds. Care was taken to ensure that it did not elapse the 15-second mark and so was called out to test at 14s and so to give time for the movement from the test tube to the spotting tile for testing.
Results:
I will now list all 3 results I carried out, followed by the most important average. I will be examining the average only in the follow-up analysis and conclusion.
[(Test 1 + Test 2 + Test 3) / 3 = AVERAGE]
Results #1:
Results #2:
Results #3:
I compiled the following graph from the average results:
1/Time Results: (Answers taken to four decimal places)
As mentioned before, for the purposes of good accuracy I repeated the experiment three times, and took an average as my final result. Thus, I will only be analyzing the Average results.
Analysis:
I feel that my investigation did work out well because I achieved a good range of results which I saw after I drew my graph. My results evidently prove that, as the temperature of the reactants increase the rate of reaction increases. Though only up to a certain temperature, beyond the optimum temperature the rate of reaction begins to decline until the enzyme denatures.
The optimum temperature of 75°C may seem extremely high for an amylase enzyme, however from my preliminary experiment I found out that a BACTERIAL amylase enzyme acts differently and has a much greater optimum. Thus, I was not surprised to find the optimum of 75°C in this official experiment. (Surprisingly, this was the optimum temperature out of the correct results I obtained in my preliminary experiment)
From the experiment I found out that temperature is a beneficial variable that increase the rate of reaction. It speeds the reaction of amylase enzyme and so digests the starch molecules into simpler maltose molecules.
From looking at my results I notice that as the temperature increases from 40°C - 75°C the time taken for the starch to be broken down by the amylase decreases from 735s (12.25 minutes) – 135s (2.25 minutes). The time of 135s was the fastest observed and so the 75°C temperature proves to be the Optimum Temperature (column in the table highlighted GREEN)
The Optimum Temperature is the temperature where the amylase functions most rapidly.
My Prediction of 75°C for the optimum temperature was in reply to the results achieved in the preliminary experiment. Though the preliminary results above the temperature above 75°C were declared faulty, a time of 100s for starch to be digested by amylase at a temperature of 75°C seemed remarkably fast compared to the remaining results. Thus, I predicted it to be the optimum temperature in this official experiment and is validated to be the optimum temperature.
The downfall of the reaction was also successfully achieved, unlike with the preliminary. It can be seen that as the reaction progressively decreases from 80°C - 90°C and the time taken for the reaction increases from 223s (3.71 minutes) – 1440 (24 minutes). The rate of reaction has been proved to decrease after the optimum temperature, and so surely validates the experiment to be successful one.
Conclusion:
As stated in my prediction, “as the temperature is increased the rate of reaction between the amylase and the starch increases. However, the temperature increases the rate of reaction only up to a certain point whilst still proving to be beneficial.” This point is the 75°C mark i.e. the optimum temperature. After this temperature the rate of reaction declines progressively until it reaches its denatured mark which as can seen from the graph and table- above the temperature of 90°C.
Using scientific knowledge to back up the conclusion achieved from the results:
When temperature or thermal energy is transferred to a substance it will cause more movement (In a solid will cause more vibration until enough bonds broken to forma liquid. In a liquid will cause much for movements and the remaining few bonds will be broken eventually forming a gas. In a gas this will cause faster random movement). When the thermal energy is transferred to the starch and amylase molecules (liquid state) it will cause much more collisions. Reactants need collisions to react. Hence, more collision will ultimately cause a faster rate of reaction. The optimum temperature (when looking at the results shows its 75°C) is a point that identifies where the enzyme works most rapidly. Obviously the enzyme essential, where the enzyme works most rapidly then the rate of reaction will be greater. However, the enzyme has a unique shape called an active site (an active site is the area where a substrate fits in and reacts).
At a temperature above this optimum temperature the site progressively changes up to a point where it has jostled and reformed so much that it can no longer act as a ‘lock’ and the substrate ‘key’ can no longer fit in and react with it. This point is were the enzyme is said to be denatured. From my results I notice that the enzyme must be denatured shortly above the 90°C mark (as can be seen by such a long length of time [1440s]).
The preliminary results are very faulty as they show that the enzyme is denatured straight after the optimum temperature-only a temperature of 80°C (5°C up, and so is very unlikely).
Successfully my conclusion does agree with my prediction and theoretical prediction (can be found in the preliminary section).
Evaluating:
On the whole, I feel that my official investigation worked out well. My method gave results that were reliable and so could always be counted on to be correct this is because I achieved accurate results by choosing particular apparatus such as the essential water bath. I choose to use the water bath because of its accuracy and that it rules out the possibility of human error. The mistakes which I learned from my preliminary experiment led my to me to make the decision that I must improve my technique by using a very accurate piece of apparatus of which I think I have made an intelligent choice.
I am sure that my experiment would not have succeeded if I was to repeat the experiment simply using beakers of water and then ‘trying’ to maintain that constant temperature.
Most things in my investigation turned out the way I predicted. Also nothing dangerous or disastrous occurred because I carried out my investigation according to my safety procedures.
All of my results seemed to fit with the main pattern as the comparisons of the graphs show. The graph has a similar shape and all the points fit well.
I also felt that I had enough correct results to show a conclusion as the results match with my prediction and my background reading.
- This successful experiment was due to recognising the mistakes in the preliminary experiment, such as the way the method was conducted, the use of some inappropriate apparatus and lack of concentration. I changed all these, and successfully obtained accurate results of which I am pleased about.
[Note: can I please be awarded a mark out of 8-8-8-6 i.e. planning-obtaining evidence-analysis and conclusion-evaluation]
Thanks ☺