The rate of enzyme catalyzed reactions

Last updated: 17/02/2022

AQA A-Level Biology Proteins The rate of enzyme catalyzed reactions

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Question 1 of 28

1. Question
What happens to the rate of a reaction as enzyme concentration increases?
- The rate increases
- The rate decreases
- The rate increases to an optimum and then decreases
- The rate increases and then levels off
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Question 2 of 28

2. Question
What happens to the rate of a reaction as enzyme temperature increases?
- The rate increases to an optimum and then decreases
- The rate increases
- The rate decreases
- The rate increases and then levels off
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Question 3 of 28

3. Question
What happens to the rate of a reaction as substrate concentration increases?
- The rate increases and then levels off
- The rate increases
- The rate decreases
- The rate increases to an optimum and then decreases
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Question 4 of 28

4. Question
What happens to the rate of a reaction as enzyme pH increases?
- The rate increases to an optimum and then decreases
- The rate increases
- The rate decreases
- The rate increases and then levels off
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Question 5 of 28

5. Question
Which of the following is not a limitation of the lock and key model?
- It does not result in the formation of an enzyme-substrate complex
- It does not easily explain how activation energy is lowered
- It does not easily explain the role of competitive inhibitors
- It does not easily explain the role of non-competitive inhibitors
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Question 6 of 28

6. Question
Which factor causes increased kinetic energy?
- Increased temperature
- Increased pH
- Increased enzyme concentration
- Increased substrate concentration
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Question 7 of 28

7. Question
The progress of an enzyme-catalysed reaction can be measured by monitoring which of the following?
- The formation of products
- The formation of substrate
- The disappearance of products
- The concentration of the enzyme
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Question 8 of 28

8. Question
The progress of an enzyme-catalysed reaction can be measured by monitoring which of the following?
- The disappearance of the substrate
- Heat production
- The disappearance of products
- The concentration of the enzyme
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Question 9 of 28

9. Question
As an enzyme-catalyzed reaction proceeds, there is…
- decreasing substrate, and increasing product
- increasing substrate and increasing product
- decreasing substrate and decreasing product
- increasing substrate and decreasing product
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Question 10 of 28

10. Question
Why does the rate of disappearance of substrate decrease over time in an enzyme-catalyzed reaction?
- The concentration of substrate decreases and so interactions between substrate and enzyme become less frequent
- The concentration of substrate decreases and so interactions between substrate and enzyme become more frequent
- The concentration of substrate increases and so interactions between substrate and enzyme become less frequent
- The concentration of substrate increases and so interactions between substrate and enzyme become more frequent
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Question 11 of 28

11. Question
Why does the rate of appearance of product decrease over time in an enzyme-catalyzed reaction?
- Product levels will have increased and product molecules may prevent substrate from reaching the active site
- Product levels will have decreased and product molecules may prevent substrate from reaching the active site
- Product levels will have increased and product molecules may be permanently bound into the active site
- Product levels will have increased and changed the temperature of the reaction
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Question 12 of 28

12. Question
How can a change in the rate of a reaction be determined from a graph measuring substrate decrease?
- Comparing the gradient of the tangent to the curve at given points
- Measuring the area under the curve of the graph
- Determining the substrate concentration at given points on the graph
- Determining the time elapsed at a given points on the graph
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Question 13 of 28

13. Question
What effect does a rise in temperature have on molecules in a closed system?
- It increases their kinetic energy and likelihood of colliding
- It increases their potential energy
- It decreases their kinetic energy and likelihood of colliding
- It decreases their potential energy
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Question 14 of 28

14. Question
What happens to the rate of an enzyme-catalyzed reaction as the temperature is increased from 0°C to 100°C?
- The rate of reaction increases until the optimum tempertature is reached and then decreases until the enzyme becomes denatured
- The rate of reaction increases continuously until the enzyme becomes denatured
- The rate of reaction increases until the optimum tempertature is reached and then remains at that level until the substrate is used up completely
- The rate of reaction gradually increases until the optimum tempertature is reached and then gradually decreases until the temperature reaches 100°C.
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Question 15 of 28

15. Question
At temperatures slightly higher than optimum, what happens to an enzymes active site?
- It begins to change shape and substrate does not fit as easily
- It begins to change shape but substrate binding will not be affected
- It keeps the same shape but substrate does not fit as easily
- It keeps the same shape and substrate binding is not affected
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Question 16 of 28

16. Question
At temperatures above 60°C, what happens to most enzymes?
- They change shape permanently and stop working altogether
- They change shape and stop working temporarily but can recover
- They change shape permanently but can still work a little
- They change shape temporarily but stop working altogether
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Question 17 of 28

17. Question
What is denaturation of an enzyme?
- A permanent change that prevents the enzyme from functioning again
- A temporary change that can be recovered from with enzyme functioning again
- A permanent change that still allows the enzyme to function a little
- A permanent change that occurs at any temperature higher than the optimum temperature of an enzyme
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Question 18 of 28

18. Question
What is the appopriate term to describe the effect of high temperature on an enzyme?
- Denaturation
- Killing
- Cooking
- Destroying
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Question 19 of 28

19. Question
Which of the following can cause denaturation of an enzyme? 1. High temperature 2. Extreme pH 3. High substrate concentration
- 1 & 2
- 1 only
- 1, 2 & 3
- None of the above
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Question 20 of 28

20. Question
Which of the following will not affect the rate of an enzyme-catalysed reaction?
- Temperature
- pH
- Enzyme concentration
- Size of the enzyme
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Question 21 of 28

21. Question
At pH slightly higher or lower than optimum, what happens to an enzymes active site?
- Charges on amino acids in the active site are altered and substrate does not fit as easily
- Charges on amino acids in the active site are altered but substrate binding will not be affected
- Charges on amino acids in the active site are unaffected and substrate binding will not be affected
- Charges on amino acids in the active site are unaffected but substrate does not fit as easily
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Question 22 of 28

22. Question
What is the appopriate term to describe the effect of extreme pH on an enzyme?
- Denaturation
- Acidification
- Killing
- Alkalinisation
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Question 23 of 28

23. Question
In the presence of excess substrate, which of the following best describes the impact of increasing enzyme concentration on reaction rate?
- There are more active sites to act on substrate so reaction rate increases
- There are fewer active sites to act on substrate so reaction rate increases
- There are more active sites to act on substrate so reaction rate decreases
- There are fewer active sites to act on substrate so reaction rate decreases
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Question 24 of 28

24. Question
In the presence of excess substrate, which of the following best describes the impact of decreasing enzyme concentration on reaction rate?
- There are fewer active sites to act on substrate so reaction rate decreases
- There are more active sites to act on substrate so reaction rate increases
- There are fewer active sites to act on substrate so reaction rate increases
- There are more active sites to act on substrate so reaction rate decreases
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Question 25 of 28

25. Question
In the presence of fixed amounts of enzyme, which of the following best describes the impact of increasing substrate concentration on reaction rate?
- The likelihood of collisions between substrate and active site increases, so does the reaction rate
- The likelihood of collisions between substrate and active site decreases, so does the reaction rate
- The likelihood of collisions between substrate and active site decreases, but the reaction rate increases
- The likelihood of collisions between substrate and active site increases, but the reaction rate decreases
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Question 26 of 28

26. Question
In the presence of fixed amounts of enzyme, which of the following best describes the impact of decreasing substrate concentration on reaction rate?
- There likelihood of collison between substrate and active site decreases, so does the reaction rate
- There likelihood of collison between substrate and active site increases, so does the reaction rate
- There likelihood of collison between substrate and active site decreases, but the reaction rate increases
- There likelihood of collison between substrate and active site increases, but the reaction rate decreases
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Question 27 of 28

27. Question
While keeping the amount of enzyme and substrate constant, what effect will increasing the volume of liquid in the test tube have on reaction rate?
- It will decrease the reaction rate as the concentations of substrate and enzyme will be decreased
- It will decrease the reaction rate as the concentations of substrate and enzyme will be increased
- As the amount of enzyme and substrate remain constant it will have no effect on reaction rate
- It will increase the reaction rate as the enzyme and substrate will be able to move faster in the bigger volume
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Question 28 of 28

28. Question
While keeping the concentration of enzyme and substrate constant, what effect will increasing the volume of liquid in the test tube have on reaction rate?
- As the concentration of enzyme and substrate remain constant it will have no effect on reaction rate
- It will decrease the reaction rate as the enzyme and substrate will struggle to collide with each other in the bigger volume
- It will increase the reaction rate as the enzyme and substrate will be able to move faster in the bigger volume
- It will have no effect on reaction rate despite their being less enzyme and substrate
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