SBI 4U Enzyme quiz
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____1.When free energy is released during a chemical reaction it is called
a. / an endergonic reaction / d. / an exothermic reactionb. / an isothermic reaction / e. / an endothermic reaction
c. / a nuclear reaction
____2.Of the following characteristics, which one is not true about enzymes?
a. / They are essential to the metabolism of cells for the conversion of energy.b. / They function best at specific temperatures but break down at high temperatures.
c. / Some enzymes need activators or cofactors.
d. / They function best at a particular pH.
e. / They undergo major chemical change after reacting with their specific substrate.
____3.At which temperature would you expect any enzyme extracted from a human tissue to have its optimal performance?
a. / 5C / d. / 37Cb. / 10C / e. / 95C
c. / 25C
____4.The activity of an enzyme can be altered by changing the pH of its surroundings slightly. This change in pH works by
a. / causing the enzyme to precipitateb. / masking its active site
c. / increasing the activation energy of the reaction
d. / breaking its peptide bonds
e. / altering its three dimensional shape
____5.Enzymes work as catalysts by doing which of the following?
a. / increasing the free energy of the reactantsb. / decreasing the free energy of the reactants
c. / increasing the activation energy
d. / decreasing the activation energy
e. / bypassing the need for a transition state to occur
____6.Which of the following statements about enzymes is not true?
a. / They are proteins with tertiary or quaternary structures.b. / They are very specific for the substrate to which they bind.
c. / They will bind their substrate and any isomer of their substrate.
d. / Their names usually end in 'ase.'
e. / All of the above statements are true.
____7.Which of the following statements regarding enzyme inhibition is incorrect?
a. / Competitive inhibitors have a similar structure to the normal substrate.b. / Competitive inhibitors bind to the active site of an enzyme.
c. / Noncompetitive inhibition can be overcome by adding more substrate.
d. / Noncompetitive inhibitors do not have a similar structure to the normal substrate.
e. / Noncompetitive inhibitors do not bind to the active site of an enzyme.
____8.Which of the following statements concerning allosteric regulation is not true?
a. / Allosteric sites are usually located next to, but separate from, the active site.b. / Alosterically controlled enzymes usually have quaternary structure.
c. / 'Activators' tend to keep all the active sites available to the normal substrate.
d. / 'Allosteric inhibitors' stabilize the inactive form of the enzyme.
e. / Allosteric regulators attach to their sites using weak bonds.
____9.Which of the following is not an application of enzymes for commercial or industrial use?
a. / starch hydrolysis for the food industryb. / proteases to coagulate milk for the manufacture of cheese
c. / removal of lactose from dairy products for lactose intolerant people
d. / lipases added to crude oil before being processed into plastics
e. / proteases added to detergents to remove protein-based stains
____10.
enzyme m / enzyme nIn the metabolic pathway M------> / N------>P, / enzyme m can bind to its
substrate M and also to P. The binding of P to enzyme m leads to
a. / precursor activation / c. / feedback inhibition / e. / substrate activationb. / competitive inhibition / d. / positive inhibition
Application: (5 marks each)
1) Draw a potential energy diagram for an endothermic reaction and explain what is being shown in the diagram.
2) Use an example of a buffer system (bicarbonate buffer system) to explain what a buffer is and how they work.
3) Create a chart to summarize how enzyme activity can be regulated.
SBI 4U Enzyme quiz
Answer Section
MULTIPLE CHOICE
1.ANS:DPTS:1REF:K/UOBJ:1.3
STA:MP1.01
2.ANS:EPTS:1REF:K/UOBJ:1.4
STA:MP1.03
3.ANS:DPTS:1REF:K/UOBJ:1.4
STA:MP1.03
4.ANS:EPTS:1REF:K/UOBJ:1.4
STA:MP1.03
5.ANS:DPTS:1REF:K/UOBJ:1.4
STA:MP1.03
6.ANS:CPTS:1REF:K/UOBJ:1.4
STA:MP1.03
7.ANS:CPTS:1REF:K/UOBJ:1.4
STA:MP1.03
8.ANS:APTS:1REF:K/UOBJ:1.4
STA:MP1.03
9.ANS:DPTS:1REF:MCOBJ:1.4
STA:MP3.02
10.ANS:CPTS:1