Paper 4 H - SAMPLE SET 1 Q3
3) Amylase catalyses the breakdown of starch into sugars.
A student investigated the effect of amylase on the reaction at different temperatures.
Figure 4 shows the apparatus the student used.
A student investigated the effect of amylase on the reaction at different temperatures.
Figure 4 shows the apparatus the student used.
This is the method used.
Table 2 shows the student’s results.
- Put starch suspension into a test tube.
- Add amylase solution.
- Put the test tube in a beaker of water at 15 °C.
- Remove a small sample of the mixture every 30 seconds and put in a spotting tile.
- Test the sample for starch.
- Time how long it takes to break down all of the starch in the mixture.
- Repeat steps 1–5 at 20 °C, 25 °C and 30 °C. 8. Repeat for each temperature twice more.
Table 2 shows the student’s results.
3.1) One of the results in Table 2 is anomalous.
Draw a ring around the anomalous result. [1 mark]
3.2) Calculate the mean for 30 °C. [1 mark]
Figure 5 shows a graph of the student’s results.
Draw a ring around the anomalous result. [1 mark]
3.2) Calculate the mean for 30 °C. [1 mark]
Figure 5 shows a graph of the student’s results.
3.3) Use the graph to predict how long it would take to break down all of the starch at 10 °C. [1 mark]
Time = __________ minutes
3.4) The student tested samples of the mixture for starch every 30 seconds.
In each test she added one drop of iodine to the sample in the spotting tile.
Predict the colour of the samples from the 20 °C test at 4.0 minutes and 7.0 minutes. [2 marks]
Colour at 4.0 minutes ______________________________
Colour at 7.0 minutes ______________________________
3.5) The student did a fourth test at 30 °C.
In this test the starch did not break down, even after 45 minutes.
Why did the amylase not break down the starch in this test? [1 mark]
Tick one box.
In each test she added one drop of iodine to the sample in the spotting tile.
Predict the colour of the samples from the 20 °C test at 4.0 minutes and 7.0 minutes. [2 marks]
Colour at 4.0 minutes ______________________________
Colour at 7.0 minutes ______________________________
3.5) The student did a fourth test at 30 °C.
In this test the starch did not break down, even after 45 minutes.
Why did the amylase not break down the starch in this test? [1 mark]
Tick one box.
3.6) The student made the following conclusion about the optimum temperature for amylase to work at.
‘Amylase works fastest at 40 °C’
Her teacher said that this is not a valid conclusion from her results.
Describe how the student could change her method to give results that would improve the validity of her conclusion. [6 marks]
(Total for Question 1 = 12 marks)