Multiple Choice Questions (MCQ) topic quiz
Enzymes
Instructions and answers for teachers
These instructions cover the learner activity section which can be found on page 11.
This Lesson Element supports OCR AS and A Level Biology A (H020/H420) and Biology B
(Advancing Biology) (H022/H422).
When distributing the activity section to the learners either as a printed copy or as a
Word file you will need to remove the teacher instructions section.
The Activity
This Lesson Element is a teaching and learning resource containing 20 multiple choice
questions (MCQs) on the theme of enzymes. Some questions might require synoptic
thinking, using knowledge and ideas from various topics across the full A Level content.
This resource can be used to test and consolidate understanding at the end of a topic or to
revisit and refresh knowledge at a later point in the course.
Introduction
Multiple choice questions allow rapid coverage of a wide range of sub-topics.
Contrary to a widespread belief among students, multiple choice questions are not
necessarily easy – they can be easy, moderate or difficult.
The questions are written so that the incorrect answers are plausible distractors based on
common errors or misconceptions.
The questions in this quiz cover topics mainly from specification sections:
Biology A
2.1.4 Enzymes
Biology B (Advancing Biology)
2.1.3 Proteins and enzymes.
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1
© OCR 2016
Multiple Choice Questions (MCQ) topic quiz - answers
1
Which of the diagrams illustrates the way in which the rate of an enzyme-controlled
reaction depends on substrate concentration?
A
Your answer
2
When starch and amylase are mixed in the presence of iodine solution, the blue-black
colour rapidly disappears. This is due to the formation of which molecule?
A
glucose
B
glycogen
C
sucrose
D
maltose
Your answer
3
D
Which of the following enzyme groups can catalyse oxidation reactions?
A
phosphorylases
B
isomerases
C
hydrolases
D
dehydrogenases
Your answer
Version 1
2
D
© OCR 2016
4
The graph below shows an enzyme-controlled reaction. The enzyme concentration is
kept constant.
At concentrations of substrate greater than X, which of the following statements is
true?
A
The rate of reaction is limited by enzyme concentration.
B
The rate of reaction tends towards zero.
C
The substrate has an inhibitory effect.
D
The products have an inhibitory effect.
Your answer
5
Enzymes differ from inorganic catalysts in that they are highly specific.
Which property of an enzyme is responsible for this specificity?
A
The insoluble nature of enzymes.
B
The high molecular mass of enzymes.
C
The surface configuration of enzymes.
D
The absence of metallic ions in an enzyme.
Your answer
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A
3
C
© OCR 2016
6
7
What is the approximate temperature coefficient (Q10) of an enzyme-controlled reaction?
A
50
B
10
C
2
D
1
Your answer
C
Your answer
C
Which of the enzymes below catalyses the following reaction?
triglyceride → glycerol + 3 fatty acids
8
A
decarboxylase
B
dehydrogenase
C
hydrolase
D
oxidase
Succinic acid dehydrogenase is the enzyme which catalyses the oxidation of succinic
acid during cell respiration. If malonic acid is added to the system, the rate of reaction
is reduced. An increase in the substrate concentration, succinic acid, increases the
rate of reaction again.
Using this information what might be deduced about the action of malonic acid?
A
It decreases the pH of the system.
B
It forms a permanent attachment to the active site of the enzyme.
C
It has a similar molecular configuration to that of succinic acid.
D
It acts as a coenzyme.
Your answer
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4
C
© OCR 2016
9
In the following diagram, each of the curves P, Q and R represents an enzymecontrolled reaction in one of the following situations:

with the enzyme uninhibited

with a non-competitive inhibitor

with a competitive inhibitor.
Which curve, P, Q or R, represents each situation?
uninhibited
enzyme
competitive
inhibitor added
noncompetitive
inhibitor added
A
P
Q
R
B
P
R
Q
C
R
Q
P
D
R
P
Q
Your answer
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5
A
© OCR 2016
10
Which of the following is an extracellular enzyme?
A
catalase
B
DNA polymerase
C
keratin
D
trypsin
Note: Keratin is not on the Biology B
specification. Please replace with Fibrin.
Your answer
11
If other conditions were to remain constant, which one of the following changes would
explain a reduced rate of activity in an enzyme-controlled reaction?
A
increase in concentration of end-product
B
increase in substrate concentration
C
increase in enzyme concentration
D
increase in temperature towards the optimum
Your answer
12
A
a high temperature
B
an extreme pH
C
heavy metal ions
D
a low temperature
D
Which type of enzyme catalyses the conversion of a dipeptide into two separate amino
acids?
A
decarboxylase
B
dehydrogenase
C
hydrolase
D
oxidoreductase
Your answer
Version 1
A
Which one of the following conditions is least likely to denature an enzyme?
Your answer
13
D
6
C
© OCR 2016
14
The action of an enzyme depends on the specific structure of its active site.
Which of these bonds are not important in maintaining the shape of the active site?
A
ionic
B
hydrogen
C
disulfide
D
phosphodiester
Your answer
15
D
The diagram below represents reactions taking place in a bacterium in which amino
acids are produced from other amino acids by the action of specific enzymes.
The numbers 1-3 refer to different amino acids and the letters V and X refer to
different enzymes.
When an excess of amino acid 3 is added into the bacterium the rate of the
reactions is reduced. What is the cause of this?
A
end product inhibition
B
enzyme denaturation
C
excess substrate inhibiting the enzyme
D
positive feedback
Your answer
Version 1
7
A
© OCR 2016
16
A sample of a starch suspension was tested with iodine solution and the result was a
blue-black colour. A second sample of the starch suspension was tested with
Benedict’s reagent and the result was a blue colour. A third sample of the starch
suspension was mixed with amylase and incubated at 30 oC for 10 minutes and then
tested with Biuret reagent.
What was the resulting colour of the third sample?
A
blue
B
blue-black
C
brick red
D
purple
Your answer
Version 1
8
D
© OCR 2016
Questions 17 and 18 refer to the following graph.
Curve X represents the relationship between an enzyme and the concentration of its
substrate under optimal conditions and without an inhibitor.
17
Which one of the curves A, B, C or D represents the result when the same
experiment is conducted in the presence of a fixed, low concentration of a
reversible, competitive inhibitor?
Your answer
18
A
Which one of the curves A, B, C or D represents the result when the same
experiment is conducted in the presence of a fixed, low concentration of an
irreversible, non-competitive inhibitor?
Your answer
19
When an enzyme is subjected to temperatures above the optimum, it denatures.
Which of the following bonds are the first to be disrupted by high temperatures?
A
disulfide
B
hydrogen
C
ionic
D
peptide
Your answer
Version 1
B
9
B
© OCR 2016
20
Which one of the following graphs shows the effect of pH on the reaction velocity of a
typical enzyme?
Note: In each graph, the scale on the x axis is from pH 2 to pH 13.
B
Your answer
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10
© OCR 2016
Multiple Choice Questions (MCQ) topic quiz
Enzymes
Learner Activity
1
Which of the diagrams illustrates the way in which the rate of an enzyme-controlled
reaction depends on substrate concentration?
Your answer
2
When starch and amylase are mixed in the presence of iodine solution, the blue-black
colour rapidly disappears. This is due to the formation of which molecule?
A
glucose
B
glycogen
C
sucrose
D
maltose
Your answer
3
Which of the following enzyme groups can catalyse oxidation reactions?
A
phosphorylases
B
isomerases
C
hydrolases
D
dehydrogenases
Your answer
Version 1
11
© OCR 2016
4
The graph below shows an enzyme-controlled reaction. The enzyme concentration is
kept constant.
At concentrations of substrate greater than X, which of the following statements is
true?
A
The rate of reaction is limited by enzyme concentration.
B
The rate of reaction tends towards zero.
C
The substrate has an inhibitory effect.
D
The products have an inhibitory effect.
Your answer
5
Enzymes differ from inorganic catalysts in that they are highly specific.
Which property of an enzyme is responsible for this specificity?
A
The insoluble nature of enzymes.
B
The high molecular mass of enzymes.
C
The surface configuration of enzymes.
D
The absence of metallic ions in an enzyme.
Your answer
Version 1
12
© OCR 2016
6
What is the approximate temperature coefficient (Q10) of an enzyme-controlled reaction?
A
50
B
10
C
2
D
1
Your answer
7
Which of the enzymes below catalyses the following reaction?
triglyceride → glycerol + 3 fatty acids
A
decarboxylase
B
dehydrogenase
C
hydrolase
D
oxidase
Your answer
8
Succinic acid dehydrogenase is the enzyme which catalyses the oxidation of succinic
acid during cell respiration. If malonic acid is added to the system, the rate of reaction
is reduced. An increase in the substrate concentration, succinic acid, increases the
rate of reaction again.
Using this information what might be deduced about the action of malonic acid?
A
It decreases the pH of the system.
B
It forms a permanent attachment to the active site of the enzyme.
C
It has a similar molecular configuration to that of succinic acid.
D
It acts as a coenzyme.
Your answer
Version 1
13
© OCR 2016
9
In the following diagram, each of the curves P, Q and R represents an enzymecontrolled reaction in one of the following situations:

with the enzyme uninhibited

with a non-competitive inhibitor

with a competitive inhibitor.
Which curve, P, Q or R, represents each situation?
uninhibited
enzyme
competitive
inhibitor added
noncompetitive
inhibitor added
A
P
Q
R
B
P
R
Q
C
R
Q
P
D
R
P
Q
Your answer
Version 1
14
© OCR 2016
10
Which of the following is an extracellular enzyme?
A
catalase
B
DNA polymerase
C
keratin
D
trypsin
Your answer
11
If other conditions were to remain constant, which one of the following changes would
explain a reduced rate of activity in an enzyme-controlled reaction?
A
increase in concentration of end-product
B
increase in substrate concentration
C
increase in enzyme concentration
D
increase in temperature towards the optimum
Your answer
12
Which one of the following conditions is least likely to denature an enzyme?
A
a high temperature
B
an extreme pH
C
heavy metal ions
D
a low temperature
Your answer
13
Which type of enzyme catalyses the conversion of a dipeptide into two separate amino
acids?
A
decarboxylase
B
dehydrogenase
C
hydrolase
D
oxidoreductase
Your answer
Version 1
15
© OCR 2016
14
The action of an enzyme depends on the specific structure of its active site.
Which of these bonds are not important in maintaining the shape of the active site?
A
ionic
B
hydrogen
C
disulfide
D
phosphodiester
Your answer
15
The diagram below represents reactions taking place in a bacterium in which amino
acids are produced from other amino acids by the action of specific enzymes.
The numbers 1-3 refer to different amino acids and the letters V and X refer to
different enzymes.
When an excess of amino acid 3 is added into the bacterium the rate of the
reactions is reduced. What is the cause of this?
A
end product inhibition
B
enzyme denaturation
C
excess substrate inhibiting the enzyme
D
positive feedback
Your answer
Version 1
16
© OCR 2016
16
A sample of a starch suspension was tested with iodine solution and the result was a
blue-black colour. A second sample of the starch suspension was tested with
Benedict’s reagent and the result was a blue colour. A third sample of the starch
suspension was mixed with amylase and incubated at 30 oC for 10 minutes and then
tested with Biuret reagent.
What was the resulting colour of the third sample?
A
blue
B
blue-black
C
brick red
D
purple
Your answer
Version 1
17
© OCR 2016
Questions 17 and 18 refer to the following graph.
Curve X represents the relationship between an enzyme and the concentration of its
substrate under optimal conditions and without an inhibitor.
17
Which one of the curves A, B, C or D represents the result when the same
experiment is conducted in the presence of a fixed, low concentration of a
reversible, competitive inhibitor?
Your answer
18
Which one of the curves A, B, C or D represents the result when the same
experiment is conducted in the presence of a fixed, low concentration of an
irreversible, non-competitive inhibitor?
Your answer
19
When an enzyme is subjected to temperatures above the optimum, it denatures.
Which of the following bonds are the first to be disrupted by high temperatures?
A
disulfide
B
hydrogen
C
ionic
D
peptide
Your answer
Version 1
18
© OCR 2016
20
Which one of the following graphs shows the effect of pH on the reaction velocity of a
typical enzyme?
Note: In each graph, the scale on the x axis is from pH 2 to pH 13.
Your answer
Version 1
19
© OCR 2016