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Biology for IGCSE & O level - Enzymes (Section 1)

1
The 'lock and key' model is used to explain:
Answer
(B)
The specificity of enzymes.
2
Which of the following does NOT affect the rate of an enzyme-catalyzed reaction?
Answer
(C)
The size of the reaction vessel
3
How do temperature and pH affect enzyme activity?
Answer
A
B
4
Which of these are true about enzyme inhibitors?
Answer
A
B
C
5
What is the role of the active site in an enzyme?
Answer
(A)
To bind and transform the substrate.
6
What is the effect of increasing substrate concentration on the rate of an enzyme-catalyzed reaction, assuming other factors are constant?
Answer
(C)
The rate increases until saturation.
7
How does a competitive inhibitor affect an enzyme?
Answer
(A)
It binds to the active site, blocking the substrate.
8
Which of the following is the correct term for the substance that an enzyme acts upon?
Answer
(C)
Substrate
9
Which of the following is an example of an anabolic process?
Answer
(B)
Building a protein from amino acids.
10
Which term describes the substance upon which an enzyme acts?
Answer
(C)
Substrate
11
Which type of inhibitor binds to a location other than the active site?
Answer
(B)
Non-competitive inhibitor
12
Which of the following factors can influence the rate of an enzyme-catalyzed reaction?
Answer
A
B
C
D
13
Which of the following best describes the conditions under which an enzyme will be most stable?
Answer
A
B
14
Which of the following environmental conditions is most likely to cause an enzyme to denature?
Answer
(C)
A very high temperature.
15
What is the role of a substrate in an enzyme-catalyzed reaction?
Answer
(B)
To be transformed into products.
16
What is the effect of a non-competitive inhibitor on an enzyme?
Answer
A
C
17
How can pH affect enzyme activity?
Answer
A
C
18
Which of the following factors directly influences the activity of an enzyme?
Answer
(D)
The temperature of the reaction
19
What is the purpose of the 'lock and key' model?
Answer
(B)
To explain enzyme specificity.
20
How does an enzyme affect the activation energy of a chemical reaction?
Answer
(B)
It decreases the activation energy.
21
Which of the following statements best describes denaturation?
Answer
(B)
The enzyme's shape changes, rendering it non-functional.
22
Which of the following describes the optimum temperature for an enzyme?
Answer
(B)
The temperature at which the enzyme has its highest activity.
23
What happens to the enzyme when the temperature is raised significantly above its optimum temperature?
Answer
(B)
The enzyme is denatured.
24
Where on an enzyme does a substrate bind?
Answer
(B)
The active site
25
Which of the following factors influence the rate of an enzyme-catalyzed reaction?
Answer
A
B
C
D
26
Which of the following are products of the reaction: Glucose + Fructose --> Sucrose + Water (catalyzed by the enzyme sucrase)?
Answer
(C)
Sucrose and Water
27
What is the primary function of an enzyme?
Answer
(C)
To speed up chemical reactions.
28
Enzymes function as biological catalysts. What does 'catalyst' mean in this context?
Answer
(B)
A substance that speeds up chemical reactions.
29
What does the term 'optimum pH' refer to in the context of enzyme activity?
Answer
(C)
The pH at which the enzyme has maximum activity.
30
Which of the following best describes the conditions under which an enzyme will function most efficiently?
Answer
A
C
31
Which of these are products of an enzyme catalyzed reaction?
Answer
(D)
Smaller molecules
32
Which of the following is the optimum pH for many enzymes?
Answer
(C)
pH 7
33
What is the primary function of an enzyme in a biological system?
Answer
(C)
To catalyze biochemical reactions.
34
Which of the following scenarios would result in an enzyme becoming denatured?
Answer
(B)
Changing the pH of the surrounding environment
35
At what point will an enzyme start to denature?
Answer
(C)
At temperatures above its optimum
36
Which of the following best describes the specificity of enzymes?
Answer
A
D
37
What is the term used to describe the substance that an enzyme converts into products?
Answer
(B)
Substrate
38
Which of the following statements accurately describes how enzymes and substrates interact?
Answer
A
C
39
What type of bond interactions are important in maintaining the shape of an enzyme and allowing it to function?
Answer
(C)
Hydrogen bonds and van der Waals forces
40
How do enzymes affect the activation energy of a chemical reaction?
Answer
(C)
They lower the activation energy.
41
What type of molecule are enzymes primarily composed of?
Answer
(C)
Proteins
42
What do you call an enzyme that breaks down large molecules into smaller ones?
Answer
(A)
Catabolic Enzyme
43
What would be the impact of a sudden drop in pH on an enzyme's activity?
Answer
B
D
44
Which of the following are examples of factors that can denature an enzyme?
Answer
A
B
45
What happens to the rate of an enzyme-catalyzed reaction if the substrate concentration is increased, up to the point of saturation?
Answer
(C)
The rate of reaction increases.
46
How does pH influence enzyme activity?
Answer
(C)
It affects the shape of the active site, and thus its ability to bind to the substrate.
47
How does increasing the concentration of an enzyme affect the rate of a reaction, assuming the substrate concentration is not limiting?
Answer
(C)
The rate increases proportionally.
48
What is a common characteristic of the active site of an enzyme?
Answer
(B)
It has a shape that complements the substrate.
49
What can cause an enzyme to become denatured?
Answer
(A)
A change in pH
50
What is the role of an enzyme's shape in its function?
Answer
(B)
The shape determines its specific function.