Name: _______________________________________________________________Date: __________________________Block:___
Enzymes Questions
1. A function of enzymes is to
A. emulsify fats.
B. carry information to nerves.
C. catalyze chemical reactions.
D. maintain constant blood pH.
Use the following diagrams to answer question 2.
2. The structure labelled X is a(n)
A. product.
B. enzyme.
C. complex.
D. substrate.
3. Enzymes function to increase the rate of a metabolic reaction by
A. denaturing the substrate.
B. adding energy to the reaction.
C. decreasing the energy of activation.
D. increasing the concentration of the reactants.
Use the following graph to answer question 4.
4. When 10 or more grams of maltose were added to a test tube containing maltase,
A. the saturation of maltase active sites occurred.
B. the enzyme-substrate complex became unstable.
C. maltase was inactivated by high substrate concentrations.
D. high glucose product inhibited maltase by negative feedback.
Use the following diagram to answer question 5.
5. In the series of enzyme reactions shown above, product Z is able to occupy the active
site of enzyme E2. Product Z can therefore first inhibit the production of
A. X
B. E2
C. Y
D. Z
Use the following diagrams to answer question 6.
6. The diagram above represents an enzyme-catalyzed reaction. The
substance labelled X is most likely a
A. steroid.
B. protein.
C. vitamin.
D. calcium ion (Ca2+).
7. The location at which the substrate attaches to the enzyme is the
A. active site.
B. co-enzyme.
C. peptide bond.
D. hydrogen bond.
8. Evidence, either supporting or contradicting an hypothesis, is obtained by
A. stating a purpose.
B. developing a theory.
C. reaching a conclusion.
D. performing an experiment.
9. A substance that lowers the energy of activation for a metabolic reaction is called
A. an enzyme.
B. an initiator.
C. a promoter.
D. an inhibitor.
Mrs. N Gill
Biology 12
Name: _______________________________________________________________Date: __________________________Block:___
Use the following graph to answer question 10 a).
10. a) The graph represents data collected from an enzyme-catalyzed reaction in the small
intestine. Explain the results. (2 marks)
 At first, the rate of reaction increases because more collisions occur between
substrate and enzyme molecules to produce enzyme-substrate complexes which
makes more product. (1 mark)
 Eventually the rate of reaction will level off because the active sites are filled. (1
mark)
b) How would the shape of the graph below change if a large amount of concentrated acid were added to the enzyme-catalyzed reaction at
time X? Draw the the change on the graph and explain your answer. (3 marks)


The acid denatures (changes the shape of)
the enzyme, therefore no product is
produced. (1 mark)
The substrate and enzyme are unable to
form enzyme-substrate complexes, therefore
no product is produced. (1 mark)
Use the following diagram to answer question 11.
11. If substance Z inhibits enzyme 2, this will in turn inhibit the production of
A. enzyme 1.
B. enzyme 2.
C. substance W.
D. substance Y.
12. Which of the following is not a part of the theory of how an enzyme functions?
A. The shape of the active site facilitates a reaction.
B. The enzyme and substrate fit like a lock and key.
C. The enzyme lowers the activation energy required for the reaction.
D. The shape of the enzyme is permanently changed by the chemical reaction
Use the following graph to answer question 13.
13. The graph shows the effect of pH on three different enzyme catalyzed reactions.
Which of the following would best describe the effect of pH on enzyme-catalyzed
reactions?
A. enzyme action increases as pH increases
B. enzyme action decreases as pH increases
C. enzymes work best in an acid environment
D. each enzyme works best within a specific pH range
14. An enzyme acts as a catalyst because it is capable of
A. slowing down many different reactions.
B. acting as a reactant in a chemical reaction.
C. lowering the energy required for the reaction to occur.
D. providing hydrogen ions and electrons for a chemical reaction.
Use the following diagram to answer question 15.
15. In the diagram above, molecule X is acting as
A. a substrate.
B. an enzyme.
C. a coenzyme.
D. a competitive inhibitor.
16. What conditions would decrease the ability of lipase to form an enzyme-substrate complex?
A. a pH of 8.5
B. the addition of lipids
C. the addition of lead ions
D. an increase in the amount of bile available
Mrs. N Gill
Biology 12
Name: _______________________________________________________________Date: __________________________Block:___
17. An experiment was set up to measure the effect of temperature on catalase, an
enzyme found in the liver that breaks down hydrogen peroxide into water and
oxygen gas. Four labelled test tubes, each containing similar amounts of catalase
and 2 mL of hydrogen peroxide, were incubated at different temperatures. C
18. Explain how enzymes catalyze reactions in cells. (4 marks)
• The substrate(s) fit into the active site of the enzyme.
• An enzyme-substrate complex is formed.
• The product(s) are released from the enzyme leaving the enzyme unchanged. / Products are produced (explain in the process) and
released. / Enzyme is NOT changed by the reaction. / Enzyme specificity (each enzyme can only catalyze a specific reaction or can only
bind to a specific substrate). / Coenzymes or cofactors are needed by some enzymes for the reaction to proceed. / An enzyme can only
function at an optimum temperature and/or pH.
• The active site has unique shape.
• The energy of activation is lower.
any four for 1 mark each
Use the following graph to answer question 18.
19. In the graph above, the curve levels off due to the
A. addition of a strong acid.
B. addition of a competitive inhibitor.
C. conversion of all of the substrate into product.
D. substrate temporarily occupying all the active sites.
20. Vitamins act as which of the following in biochemical reactions?
A. buffers
B. enzymes
C. substrates
D. coenzymes
Use the following graph to answer question 22.
21. What would cause the change in the rate of the enzyme-catalyzed reaction at X?
A. an increase in enzyme concentration
C. a decrease in the substrate concentration
D. a decrease in the competitive inhibitor concentration
22. Which of the following does not affect the rate of an enzyme-catalyzed
reaction?
A. pH
B. temperature
C. osmotic pressure
D. substrate concentration
23. Explain how each of the following affects the rate of an enzyme-catalyzed
reaction that occurs in the mouth. (6 marks: 2 marks each)
adding more enzyme:
• increase the number of active sites available
• increase the number of collisions between enzyme and substrate
either one for 1 mark
• this would increase the rate of the reaction (1 mark)
Mrs. N Gill
Biology 12
Name: _______________________________________________________________Date: __________________________Block:___
changing the pH from 7.2 to 12:
• this would denature the enzyme
• this would decrease the number of active sites available
either one for 1 mark
• this would decrease the rate of the reaction (1 mark)
lowering the temperature from 37o
• decreasing temperature slows down the particles
• fewer particles have energy of activation
• less kinetic energy
• fewer effective collisions between substrate and enzyme
any one for 1 mark
• this would decrease the rate of the reaction (1 mark)
Use the following graph to answer question 24.
24. The graph shows the change in the rate of an enzyme-catalyzed reaction over time.
a) Explain why the rate became constant at time X. (1 mark)
• All of the active sites were occupied. (1 mark)
b) Which labelled line correctly illustrates what would occur if more enzyme was
added at time Y. Explain your answer. (2 marks)
• line A (1 mark)
• More active sites are available to bind with substrates. (1 mark)
25. Which of the following is a function of thyroxin?
A. to decrease body temperature
B. to increase the amount of ATP used by the cells
C. to increase the reabsorption of water by the kidneys
D. to decrease the breakdown of proteins in the small intestine
26. Increased secretion by the thyroid gland results in which of the following?
A. increased use of oxygen
B. decreased body temperature
C. increased synthesis of glycogen
D. decreased carbon dioxide production
27. What could be added to an enzyme-catalyzed reaction to decrease its rate?
A. enzymes
B. substrate
C. lead ions
D. coenzymes
28. Which of the graphs below represents the relationship between the rate of an enzyme-catalyzed
reaction and temperature? D
29. The addition of heavy metals, boiling water or acid all have the same effect on the rate of an enzyme-catalyzed reaction. Describe the
effect that these additions have on the enzyme and the reaction rate. (4 marks)
• They slow the rate of the reaction (1 mark) by denaturing the enzyme (1 mark).
• Fewer enzyme-substrate complexes can be formed (1 mark) because the enzyme and substrate do not fit as the active site has changed (1
mark).
Mrs. N Gill
Biology 12
Name: _______________________________________________________________Date: __________________________Block:___
Use the following graphs to answer question 30.
30. Graph 1 represents the rate of reaction between lipase and its substrate. In graph 2, what occurred at time X that caused the change in
the reaction?
A. Fat was added.
B. The pH was changed from 5 to 8.
C. A competitive inhibitor was added.
31. An experiment was conducted to measure the effect of temperature on an enzyme isolated from the small intestine. Data was
collected and graphed as shown below.
Explain why the following temperatures change the activity rate of the enzyme.
a.
(1 mark)
• The molecules move and react faster with increased
temperature.
• As temperature increases from 0 C to 35 C, the rate of
enzyme activity increases because the average kinetic energy of
the molecules increases.
either one for 1 mark
b.
(1 mark)
• This is the optimum temperature for the enzyme. (1 mark)
c.
(2 marks)
• The hydrogen bonds break and the enzyme loses the shape of
its active site.
• It can no longer combine with the substrate because the kinetic energy of the enzyme and substrate molecules is too great for as
many enzyme-substrate complexes to form.
• Denaturation is beginning to occur.
any two for 1 mark each
EXTRA QUESTIONS:------------------------------------------------------------------------------------ -----------------------------------------------
Mrs. N Gill
Biology 12
Name: _______________________________________________________________Date: __________________________Block:___
Use the following diagrams to answer question 32.
32. The diagram illustrates a reaction that occurs in the small intestine. Molecule X is the enzyme Maltase. Give the specific name for:
a) Molecule Y: (1 mark) • maltose (1 mark)
b) In a laboratory experiment, substance Y was added in increasing amounts until it eventually had no effect on the rate of the reaction.
Explain why. (1 mark)
• The active sites of the enzymes were occupied. (1 mark)
c) A solution containing lead ions was added to the reaction. How will the addition of this solution affect the reaction? Explain why. (2
marks)
• The rate of the reaction will decrease (1 mark) because the enzyme has been denatured by a non-competitive inhibitor (binds to
enzyme somewhere else, not active site) causing a change in shape, no ES complex, no products formed. (1 mark).
Use the following symbols to answer question 21
21. Using all of the symbols above as often as necessary, produce a diagram to illustrate how enzymes function. Explain your diagram.
(You may use a pencil for your diagram.)
(4 marks: 2 marks for diagram; 2 marks for explanation)
(Note: First step is not required in the diagram. The diagram does not need to be labelled.)
• substrate attaches to enzyme (at active site) and an enzyme-substrate complex is
formed
• product is formed from substrate
• products are released
• enzyme is re-used
• enzyme decreases the activation energy
• active site is specific to the enzyme OR substrate fits into active site
• reaction occurs any two for 1 mark each
Mrs. N Gill
Biology 12
Name: _______________________________________________________________Date: __________________________Block:___
35. An experiment was conducted to measure the effects of the presence of thyroxin and temperature on oxygen use in human tissue cells.
Two tissue samples were prepared as shown below.
Sample A: 50 grams of muscle tissue was added to a nutrient solution.
Sample B: 50 grams of muscle tissue was added to a thyroxin and nutrient solution.
Oxygen consumption was measured at various temperatures. The results are shown below.
a) Use the grid provided to graph the data in the table above. Label the x-axis as temperature.
(2 marks: 1 mark for correct scale and labels; 1 mark for plotting and lines)
b) Based on your
graph of the data
for sample B,
predict the amount
of oxygen
consumed per hour
at 20oC. (1 mark)
• 13 – 14 mL/hour
c) Explain the
difference
observed in the
results of samples
A and B. (1 mark)
• Thyroxin
increases the
consumption of
oxygen (metabolic
rate). (1 mark)
d) Explain the results for sample B at each of the following temperatures. (3 marks: 1 mark each)
15oC:
• The particles move slowly so that the metabolic rate is low resulting in little oxygen being consumed. (1 mark)
35oC:
• The temperature is near optimum for the hormone function and therefore metabolic rate is high in sample B. This leads to high oxygen
consumption. (1 mark)
55oC:
• The hormone has begun to denature so the metabolic rate slows and oxygen consumption is lower.
• The enzymes in the muscle tissue have begun to denature.
either one for 1 mark
Mrs. N Gill
Biology 12