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B2: Quiz 4 – Answers
B2: Quiz 4 – Answers
1)
a)
i) Brown/ orange
ii) Blue/ black
b) We fill all of the depressions in the spotting tile with a little bit of iodine. We heat the water in the beaker using a Bunsen burner and use a thermometer to get the water to the temperature that we are testing. We have the amylase solution and the starch solution in separate test tubes in the beaker containing water. When they are the desired temperature, we pour one of the test tubes into the other and the amylase enzymes will start breaking down the starch. As soon as the two test tubes are poured together, we start a stopwatch. Every 30 seconds, we use a pipette to transfer a small sample from the mixture to the depressions that are filled with iodine on the spotting tile. We continue to take samples every 30 seconds for a certain period of time (e.g. 5 or 10 minutes). We then note the colour of the depressions in the spotting tiles.
We repeat the same process for quite a few different temperatures. When we undertake the experiment for different temperatures, we need to keep the concentrations and volumes of the amylase solution and starch solution the same. We also need to keep the pH of all of the solutions the same as well
c)
i) The rate of reaction for amylase was the greatest at 40°C. We know that this is the case because the samples in the spotting tile stayed brown-orange at an earlier time; they stay brown-orange at 2 minutes
ii) A 60°C temperature is too high for amylase, which resulted in the enzyme denaturing. Denaturing is where the excessive temperature causes the bonds that make up the enzyme to break which changes the shape of the active site. As the shape of the active site has changed, the substrate (starch) can no longer enter the active site of the enzyme (amylase), which means that fewer reactions happen and the rate of reaction decreases
d)
i) We would set up the experiment in exactly the same way. We would then use a few different pHs for the solutions of amylase and starch, such as a pH of 4, 5, 6, 7, 8, 9 etc.
ii) We would need to keep:
a)
i) Brown/ orange
ii) Blue/ black
b) We fill all of the depressions in the spotting tile with a little bit of iodine. We heat the water in the beaker using a Bunsen burner and use a thermometer to get the water to the temperature that we are testing. We have the amylase solution and the starch solution in separate test tubes in the beaker containing water. When they are the desired temperature, we pour one of the test tubes into the other and the amylase enzymes will start breaking down the starch. As soon as the two test tubes are poured together, we start a stopwatch. Every 30 seconds, we use a pipette to transfer a small sample from the mixture to the depressions that are filled with iodine on the spotting tile. We continue to take samples every 30 seconds for a certain period of time (e.g. 5 or 10 minutes). We then note the colour of the depressions in the spotting tiles.
We repeat the same process for quite a few different temperatures. When we undertake the experiment for different temperatures, we need to keep the concentrations and volumes of the amylase solution and starch solution the same. We also need to keep the pH of all of the solutions the same as well
c)
i) The rate of reaction for amylase was the greatest at 40°C. We know that this is the case because the samples in the spotting tile stayed brown-orange at an earlier time; they stay brown-orange at 2 minutes
ii) A 60°C temperature is too high for amylase, which resulted in the enzyme denaturing. Denaturing is where the excessive temperature causes the bonds that make up the enzyme to break which changes the shape of the active site. As the shape of the active site has changed, the substrate (starch) can no longer enter the active site of the enzyme (amylase), which means that fewer reactions happen and the rate of reaction decreases
d)
i) We would set up the experiment in exactly the same way. We would then use a few different pHs for the solutions of amylase and starch, such as a pH of 4, 5, 6, 7, 8, 9 etc.
ii) We would need to keep:
- the temperature the same
- the volumes and concentrations of the amylase and starch solution the same
Questions
1) We are going to be investigating how the rate of reaction for the enzyme amylase is affected by temperature. The enzyme amylase breaks down starch into maltose.
a) We are able to use iodine to test for the presence of starch.
i) What colour is iodine when no starch is present?
ii) What colour does iodine when iodine is present?
We carry out the experiment using the equipment below.
1) We are going to be investigating how the rate of reaction for the enzyme amylase is affected by temperature. The enzyme amylase breaks down starch into maltose.
a) We are able to use iodine to test for the presence of starch.
i) What colour is iodine when no starch is present?
ii) What colour does iodine when iodine is present?
We carry out the experiment using the equipment below.
b) Explain how we can use the equipment above to investigate the effect that temperature has on the rate of reaction of amylase. Write quite a lot for this answer.
c) The student completes the experiment and their results are shown in the table below.
c) The student completes the experiment and their results are shown in the table below.
i) For which temperature was the rate of reaction of amylase the greatest? Explain your answer.
ii) When amylase was at 60°C, it did not break down all of the starch by the end of the 5 minutes. Explain why.
d)
i) Explain how we could modify the experiment to investigate the effect that pH has on the rate of reaction for an enzyme. You only need to give the variable that you would change.
ii) Give a few variables that you would need to keep constant when investigating the effect that pH has on the rate of reaction of an enzyme.
ii) When amylase was at 60°C, it did not break down all of the starch by the end of the 5 minutes. Explain why.
d)
i) Explain how we could modify the experiment to investigate the effect that pH has on the rate of reaction for an enzyme. You only need to give the variable that you would change.
ii) Give a few variables that you would need to keep constant when investigating the effect that pH has on the rate of reaction of an enzyme.