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Biology for IGCSE & O level - Enzymes (Section 2)

1
Which of the following is a characteristic of all enzymes?
Answer
(C)
They speed up chemical reactions.
2
Which of the following are true regarding enzyme-substrate interactions?
Answer
A
B
3
What is the effect of a competitive inhibitor on an enzyme-catalyzed reaction?
Answer
(C)
It prevents the substrate from binding to the active site.
4
What are the common effects of competitive inhibition on enzyme activity?
Answer
A
C
D
5
Which of the following best describes the specificity of an enzyme?
Answer
(D)
An enzyme catalyzes a specific reaction or set of reactions.
6
How do enzymes influence the activation energy of a chemical reaction?
Answer
(C)
They lower activation energy.
7
Which of the following is true regarding enzyme-substrate interactions?
Answer
A
B
8
What will be the effect of increasing the concentration of an enzyme in a reaction?
Answer
(B)
The rate of the reaction will increase, up to a certain point.
9
In the process of enzyme catalysis, what happens after the substrate binds to the active site?
Answer
A
B
D
10
What is the term for the process by which an enzyme's shape is altered, leading to a loss of function?
Answer
(C)
Denaturation
11
Enzymes speed up reactions by:
Answer
(B)
Decreasing the activation energy.
12
Which of the following is NOT a way in which enzymes function?
Answer
(B)
They are consumed in reactions.
13
What is the impact of a competitive inhibitor on a reaction?
Answer
A
C
14
What is a common characteristic of the active site of an enzyme?
Answer
(C)
It has a complementary shape to the substrate.
15
Which of the following are true regarding enzymes?
Answer
A
C
D
16
Which of the following factors can potentially lead to the denaturation of an enzyme?
Answer
A
B
17
What is the main function of enzymes in biological systems?
Answer
(C)
To speed up chemical reactions.
18
Which of the following statements describes the effect of a competitive inhibitor on enzyme activity?
Answer
(A)
It binds to the active site, preventing substrate binding.
19
What is the 'active site' of an enzyme?
Answer
(B)
The part of the enzyme where the substrate binds.
20
What is the effect of an inhibitor on an enzyme?
Answer
A
B
D
21
Which of the following is the best example of an enzyme?
Answer
(A)
A protein that speeds up a chemical reaction.
22
What is the function of an allosteric site?
Answer
(B)
To bind inhibitors that change enzyme activity.
23
What happens to the rate of enzyme-catalyzed reactions at temperatures above the optimum?
Answer
(C)
The rate decreases.
24
What does the 'lock and key' model describe?
Answer
(C)
The specificity of enzyme action.
25
In a typical enzyme-catalyzed reaction, what is the role of the enzyme?
Answer
(C)
To lower the activation energy of the reaction.
26
What happens when an enzyme is denatured?
Answer
(B)
The enzyme changes shape and loses its function.
27
What are the primary impacts of a competitive inhibitor on an enzyme?
Answer
A
C
28
What is the role of an enzyme in a biological reaction?
Answer
A
D
29
What is the optimum temperature for most enzymes?
Answer
(C)
37°C
30
What is the effect of a non-competitive inhibitor on enzyme activity?
Answer
(B)
It binds to the allosteric site and changes the enzyme's shape.
31
What is the term for the specific region on an enzyme where the substrate binds?
Answer
(A)
Active site
32
What role do enzymes play in the human body?
Answer
B
C
33
Which statement correctly describes how enzymes are affected by the reaction they catalyze?
Answer
(C)
Enzymes are unchanged by the reaction.
34
What happens to enzyme activity when it is subjected to very low temperatures?
Answer
(C)
The enzyme's activity slows down.
35
Which of the following is true about non-competitive inhibitors?
Answer
(B)
They change the shape of the enzyme.
36
What happens to an enzyme if the temperature is raised above its optimum?
Answer
(B)
The enzyme is denatured.
37
Which of the following statements best describes the role of an enzyme?
Answer
(C)
To speed up a chemical reaction.
38
Which of these molecules is considered a substrate in the following reaction: Maltose + Water --> Glucose + Glucose?
Answer
(C)
Maltose
39
In the 'lock and key' model of enzyme action, which part of the enzyme is the 'lock'?
Answer
(B)
The active site
40
What is the role of an allosteric site on an enzyme?
Answer
(C)
It is a site where a molecule can bind and alter enzyme activity.
41
Which of the following best describes the role of an enzyme in a chemical reaction?
Answer
(C)
It speeds up the reaction.
42
What does the 'lock and key' model describe?
Answer
(B)
Enzyme specificity.
43
Which of the following statements are true about the active site of an enzyme?
Answer
A
B
D
44
Where does a substrate bind on an enzyme?
Answer
(B)
The active site
45
Which of the following are characteristics of enzymes?
Answer
A
C
D
46
Which of the following is the correct definition of a catalyst?
Answer
(A)
A substance that speeds up a chemical reaction.
47
What will happen to the rate of an enzyme-catalyzed reaction if you decrease the temperature below the optimum?
Answer
(B)
The rate decreases.
48
What is the impact of an enzyme inhibitor?
Answer
(C)
It slows down or stops the reaction.
49
What happens to the rate of an enzyme-catalyzed reaction if the pH deviates significantly from the optimum pH?
Answer
(C)
The enzyme denatures, and the rate decreases.
50
Which of the following statements correctly describes the 'induced fit' model of enzyme action?
Answer
(A)
The enzyme's active site changes shape when the substrate binds.