2 bcelc0050000019 si tom carried out an experiment to

2
|!|BCELC0050000019|!|
SI
Tom carried out an experiment to investigate the action of an enzyme. The following
diagram shows the procedure and the results of the experiment.
At the beginning 3 minutes later 30 minutes later
cloudy cloudy clear
(a) Name the enzyme added to the egg white solution. (1 mark)
(b) Explain why the solution becomes clear. (1 mark)
(c) Suggest one method to speed up the action. (1 mark)
2 cm 3 of
enzyme
solution was
added and
stirred
10 cm 3 of
egg white
solution
incubation
in 40 o
water bath
© 2019 Aristo Educational Press Ltd.
C
36

HKDSE BIOLOGY: Connecting Concepts Chapter 5
Question bank Structured questions
(d) Predict and explain the result if the test tube is placed in a water bath at
(i) 80 °C. (2 marks)
(ii) 2 °C. (2 marks)
##
(a) Protease (1)
(b) Protease breaks down the proteins of egg white into amino acids. (1)
(c) Increase the concentration of the enzyme / other reasonable answer (1)
(d) (i) The solution will remain cloudy because (1)
the enzyme will be denatured and cannot catalyse the breakdown reaction at
such a high temperature. (1)
(ii) The solution will remain cloudy because (1)
the enzyme will become inactive and lead to a low reaction rate at low
temperature. (1)
________
(7 marks)
##
Skills assessed Marks
(a) Analysing data 1
(b) Understanding basic concepts 1
(c) Understanding basic concepts 1
(d)(i) Applying concepts 2
(d)(ii) Applying concepts 2
© 2019 Aristo Educational Press Ltd.
37

HKDSE BIOLOGY: Connecting Concepts Chapter 5
Question bank Structured questions
|!|BCELB0050000020|!|
 SI
The following shows an experimental set-up used to investigate the action of amylase
on starch.
The following table shows the contents and the pH in each boiling tube.
Boiling tube
Contents inside the dialysis
tubing
pH of the contents
A starch + amylase 2
B starch + amylase 7.5
C starch + amylase 11
(a) State the action of amylase on starch. (2 marks)
(b) State the tube in which the action of amylase on starch is the fastest. Explain your
answer. (2 marks)
(c) Design a control for this experiment. (1 mark)
Boiling tube A Boiling tube B
dialysis
tubing
distilled
water
water bath
at 20 ºC
Boiling tube C
© 2019 Aristo Educational Press Ltd.
38

HKDSE BIOLOGY: Connecting Concepts Chapter 5
Question bank Structured questions
(d) Suggest and explain a method to speed up the reaction. (2 marks)
(e) Predict, if the amylase can act on starch to form the end product, whether the
distilled water surrounding the dialysis tubing contains the end product. Explain
your answer. (2 marks)
##
________
(9 marks)
##
Skills assessed Marks
(a)