Chapter 18 Regulation of Gene Expression Grade A+

Chapter 18 Regulation of Gene Expression Grade A+
Chapter 18 has been totally reorganized and so has its Test Bank. The earlier edition questions were
transferred from several Biology, Seventh Edition, chapters, and 30 questions are entirely new. Several
sections of the new Chapter 18 had no or almost no corresponding questions. Likewise, none of the
earlier questions required higher level thinking and learning skills, so nearly all of the new questions are
at Application/Analysis and Synthesis/Evaluation skill levels.


Multiple Choice Questions
1) What does the operon model attempt to explain?
A) the coordinated control of gene expression in bacteria
B) bacterial resistance to antibiotics
C) how genes move between homologous regions of DNA
D) the mechanism of viral attachment to a host cell
E) horizontal transmission of plant viruses
Answer: A
Topic: Concept 18.1
Skill: Knowledge/Comprehension

2) The role of a metabolite that controls a repressible operon is to
A) bind to the promoter region and decrease the affinity of RNA polymerase for the
promoter.
B) bind to the operator region and block the attachment of RNA polymerase to the
promoter.
C) increase the production of inactive repressor proteins.
D) bind to the repressor protein and inactivate it.
E) bind to the repressor protein and activate it.
Answer: E
Topic: Concept 18.1
Skill: Knowledge/Comprehension

3) The tryptophan operon is a repressible operon that is
A) permanently turned on.
B) turned on only when tryptophan is present in the growth medium.
C) turned off only when glucose is present in the growth medium.
D) turned on only when glucose is present in the growth medium.
E) turned off whenever tryptophan is added to the growth medium.
Answer: E
Topic: Concept 18.1
Skill: Knowledge/Comprehension

,4) This protein is produced by a regulatory gene:
A) operon
B) inducer
C) promoter
D) repressor
E) corepressor
Answer: D
Topic: Concept 18.1
Skill: Knowledge/Comprehension

5) A mutation in this section of DNA could influence the binding of RNA polymerase to the
DNA:
A) operon
B) inducer
C) promoter
D) repressor
E) corepressor
Answer: C
Topic: Concept 18.1
Skill: Knowledge/Comprehension

6) A lack of this nonprotein molecule would result in the inability of the cell to "turn off"
genes:
A) operon
B) inducer
C) promoter
D) repressor
E) corepressor
Answer: E
Topic: Concept 18.1
Skill: Knowledge/Comprehension

7) When this is taken up by the cell, it binds to the repressor so that the repressor no longer
binds to the operator:
A) operon
B) inducer
C) promoter
D) repressor
E) corepressor
Answer: B
Topic: Concept 18.1
Skill: Knowledge/Comprehension




Chapter 18, Regulation of Gene Expression 365

, 8) A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell
would result in
A) continuous transcription of the structural gene controlled by that regulator.
B) complete inhibition of transcription of the structural gene controlled by that regulator.
C) irreversible binding of the repressor to the operator.
D) inactivation of RNA polymerase by alteration of its active site.
E) continuous translation of the mRNA because of alteration of its structure.
Answer: A
Topic: Concept 18.1
Skill: Application/Analysis

9) The lactose operon is likely to be transcribed when
A) there is more glucose in the cell than lactose.
B) the cyclic AMP levels are low.
C) there is glucose but no lactose in the cell.
D) the cyclic AMP and lactose levels are both high within the cell.
E) the cAMP level is high and the lactose level is low.
Answer: D
Topic: Concept 18.1
Skill: Knowledge/Comprehension

10) Transcription of the structural genes in an inducible operon
A) occurs continuously in the cell.
B) starts when the pathway's substrate is present.
C) starts when the pathway's product is present.
D) stops when the pathway's product is present.
E) does not result in the production of enzymes.
Answer: B
Topic: Concept 18.1
Skill: Knowledge/Comprehension

11) How does active CAP induce expression of the genes of the lactose operon?
A) It terminates production of repressor molecules.
B) It degrades the substrate allolactose.
C) It stimulates splicing of the encoded genes.
D) It stimulates the binding of RNA polymerase to the promoter.
E) It binds steroid hormones and controls translation.
Answer: D
Topic: Concept 18.1
Skill: Knowledge/Comprehension

12) For a repressible operon to be transcribed, which of the following must occur?
A) A corepressor must be present.
B) RNA polymerase and the active repressor must be present.
C) RNA polymerase must bind to the promoter, and the repressor must be inactive.
D) RNA polymerase cannot be present, and the repressor must be inactive.
E) RNA polymerase must not occupy the promoter, and the repressor must be inactive.
Answer: C
Topic: Concept 18.1
Skill: Knowledge/Comprehension



366 Chapter 18, Regulation of Gene Expression