Enzymes
Q1.
Catalase is an enzyme.
Catalase controls the following reaction:
hydrogen peroxide      water  +  oxygen
A student did an investigation on catalase activity.
This is the method used.
1.      Put 1 cm3 hydrogen peroxide solution in a test tube.
2.      Add 1 cm3 of catalase solution.
•        Bubbles of oxygen are produced.
•        Bubbles cause foam to rise up the tube.
3.     Measure the maximum height of the foam.
The diagram below shows the experiment.
 
The experiment is carried out at 20 °C.
The table below shows some results from the investigation.
 
Temperature in °C	Maximum height of foam in cm	
	Test 1	Test 2	Test 3	Mean	
10	1.3	1.1	0.9	1.1	
20	0.0	3.3	3.1	3.2	
30	5.2	5.0	5.3	5.2	
40	4.2	3.5	4.4	4.0	
50	2.1	1.9	2.3	2.1	
60	0.0	0.0	0.0	0.0	
(a)     Why did the student carry out the experiment three times at each temperature?
 
Tick one box.	 	
To make the experiment more accurate		
To prove the experiment was correct		
To show the experiment was more repeatable		
(1)
(b)     The student thought one result was an anomaly.
Circle the anomaly in the table above.
(1)
(c)     What did the student do with the anomalous result?
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(1)
(d)     Look at the table above.
What conclusion can be made as the temperature increases?
 
Tick one box.	 	
Decreases the rate of reaction up to 30 °C		
Decreases the rate of reaction up to 40 °C		
Increases the rate of reaction up to 30 °C		
Increases the rate of reaction up to 40 °C		
(1)
(e)     At which temperature was catalase denatured?
 
Tick one box.	 	
10 °C		
30 °C		
40 °C		
60 °C		
(1)
(f)     The student thought the optimum temperature for catalase activity was between 30 °C and 40 °C.
How could the investigation be improved to find a more precise value for the optimum temperature?
 
Tick one box.	 	
Do the experiment at 70 °C and 80 °C		
Do the experiment at 30 °C, 35 °C and 40 °C		
Use less hydrogen peroxide solution		
Use more catalase solution		
(1)
(g)     Amylase is the enzyme that controls the breakdown of starch to glucose.
Describe how the student could investigate the effect of pH on the breakdown of starch by amylase.
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(4)
(Total 10 marks)