Biology for IGCSE & O level - Enzymes (Section 3)
1
What effect does a competitive inhibitor have on enzyme activity?
Answer(A)
It binds to the active site, blocking substrate binding.
2
What do you call the molecules that are made as the result of an enzyme-catalyzed reaction?
3
Which factors can affect the rate of an enzyme-catalyzed reaction?
4
Which of the following factors can affect the activity of an enzyme?
5
Which of the following factors can affect the rate of an enzyme-catalyzed reaction?
6
What is the role of the active site in an enzyme-catalyzed reaction?
7
How does pH affect enzyme function?
Answer(B)
It can change the enzyme's shape, affecting its activity.
8
What is the effect of a competitive inhibitor on the enzyme's activity?
Answer(A)
It decreases the rate of reaction.
9
Which of the following statements are correct regarding the active site of an enzyme?
10
Which of the following statements about enzymes are correct?
11
What does the term 'denatured' mean in relation to an enzyme?
Answer(B)
The enzyme's active site has been altered, making it unable to function.
12
Which of the following statements accurately describes the effect of an enzyme on a chemical reaction?
Answer(D)
It lowers the activation energy.
13
What happens to enzyme activity when the temperature exceeds the enzyme's optimum?
14
In the context of enzymes, what does 'specificity' refer to?
Answer(B)
The ability of an enzyme to catalyze a specific reaction or set of reactions.
15
According to the 'lock and key' model, what is the relationship between an enzyme and its substrate?
Answer(B)
The enzyme and substrate have complementary shapes.
16
What is the relationship between temperature and enzyme activity?
Answer(D)
Enzyme activity increases up to an optimum temperature, then decreases.
17
What type of reaction is catalyzed by an enzyme?
18
What is the effect of increasing temperature on the rate of an enzyme-catalyzed reaction, up to the optimum temperature?
Answer(C)
The rate of reaction increases.
19
What is the effect of a non-competitive inhibitor on an enzyme?
Answer(B)
It binds to the allosteric site, altering the enzyme's shape.
20
Which of the following is the best explanation of enzyme specificity?
Answer(A)
Enzymes can only catalyze one specific reaction.
21
What happens to the reaction rate when the enzyme concentration increases?
Answer(A)
The reaction rate increases.
22
What type of molecule are enzymes primarily composed of?
23
What is the consequence of an enzyme's active site being altered?
Answer(C)
The enzyme can no longer bind to the substrate effectively.
24
What is the role of a substrate in an enzymatic reaction?
Answer(B)
To be converted into the product of the reaction.
25
What is the effect of increasing the concentration of an enzyme on a reaction rate?
Answer(C)
The reaction rate increases.
26
How can you describe the effect of temperature on the rate of an enzymatic reaction?
Answer(C)
The rate increases up to a point and then decreases.
27
At which point do enzymes typically function best?
28
How does temperature affect the activity of an enzyme?
Answer(C)
As the temperature increases, enzyme activity increases up to a certain point, after which it decreases.
29
How does a change in pH affect the shape of an enzyme?
Answer(C)
It can alter the shape of the active site, potentially denaturing the enzyme.
30
What can be said about enzymes and temperature?
Answer(C)
Enzymes function best at a specific temperature range (optimum temperature).
31
What is the impact on the rate of reaction by adding a non-competitive inhibitor?
Answer(C)
The reaction rate decreases.
32
Which term describes the location on an enzyme where the substrate binds?
33
Which of the following factors will decrease the rate of an enzyme-catalyzed reaction?
34
What is the role of an inhibitor in an enzymatic reaction?
Answer(D)
To slow down or stop the reaction.
35
Which of the following best defines enzyme specificity?
Answer(B)
Enzymes only catalyze one specific reaction or a small set of related reactions.
36
What can be said about the specificity of enzymes?
Answer(B)
Each enzyme can only catalyze one particular metabolic reaction.
37
How might substrate concentration affect an enzyme-catalyzed reaction?
Answer(C)
Increasing substrate concentration initially increases the reaction rate but will eventually plateau.
38
What term is used to describe the optimum conditions for an enzyme?
Answer(B)
The conditions under which the enzyme functions best.
39
Answer(A)
The location on the enzyme where the reaction occurs.
40
What is the primary role of enzymes in living organisms?
Answer(C)
To catalyze biochemical reactions.
41
How does the 'lock and key' model explain enzyme action?
Answer(C)
The enzyme and the substrate have complementary shapes, like a lock and key.
42
Which of the following is the best description of the 'lock and key' model of enzyme action?
Answer(B)
An enzyme and its substrate have complementary shapes, like a lock and key.
43
In an enzymatic reaction, what is the role of the substrate?
Answer(B)
The substrate is the molecule that is broken down or transformed by the enzyme.
44
What happens when an enzyme becomes denatured?
Answer(A)
The enzyme's shape changes, and it loses its function.
45
What is the optimum pH for most enzymes?
46
What is the relationship between an enzyme and a catalyst?
Answer(A)
Enzymes are catalysts, meaning they speed up chemical reactions.
47
Which type of inhibitor binds to the active site of an enzyme?
48
Which of the following statements about enzyme specificity is true?
Answer(B)
Enzymes are highly specific, often catalyzing only one reaction.
49
What is meant by 'denaturation' of an enzyme?
Answer(B)
The enzyme undergoes a change in its shape.
50
What is the optimum pH for many enzymes?
