Cambridge International A Level Biology Revision Guide

Cambridge International AS Level Biology
Answers to end-of-chapter questions
h
24
20
16
Diameter /mm
12
8
4
0
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time at 60˚C /minutes
x-axis (horizontal axis) is labelled ‘Time
(heated) at 60 °C’, y-axis (vertical axis) is
labelled ‘Diameter’;
units given on axes, min / minutes and mm;
regular intervals on both axes (check that
0, 1, 5, 10, 30 are not regularly spaced on
x-axis);
points plotted accurately;
points joined with straight lines or
smooth curve;[5]
i enzyme was completely denatured after
30 minutes;
rate of denaturation was rapid at first and
then gradually slowed down;
data quoted;
enzyme loses tertiary structure;
substrate no longer fits into active site
/ active site loses its (specific) shape so
substrate does not fit;
AVP e.g. hydrogen bonds broken / increased
vibration of enzyme molecule; [max. 4]
j heat samples of mammalian, fungal and
bacterial amylases at different temperatures;
suitable range, e.g. between 40 °C and 120 °C;
40 °C is a control (for reference to find out size
of halo with no denaturation);
at least five temperatures, e.g. 40, 60, 80, 100,
120 °C;
heat for suitable length of time (e.g. one
hour, at least ten min);
cool to room temp / 40 °C, add equal volumes
to wells in starch–agar plates, replicate wells
in each plate (e.g. four), leave 24 hours,
test for starch, measure diameters of halos;
[max. 5]
Background information: amylase enzymes
from the bacterium Bacillus licheniformis and
the fungus Aspergillus have been developed by
biotechnology companies for use in industrial
processes. For example, a bacterial amylase
that functions in the range 90–110 °C has
been developed and is used in beer brewing
and other processes, and a fungal amylase
that operates in the range 50–60 °C is used for
pastry baking and maltose syrup production.
k pH;
substrate concentration;
enzyme concentration;[3]
[Total: 30]
Cambridge International AS and A Level Biology © Cambridge University Press 2014