Campbell's Biology, 9e (Reece et al.)Chapter 18 Regulation of Gene ExpressionChapter 18 includes new questions for every concept number; some of these questions cover new topics whereas others build on existing questions. Several new questions introduce scenarios and art, thus encouraging a higher level of thinking from students.Multiple-Choice Questions1) The role of a metabolite that controls a repressible operon is toA) 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: ETopic: Concept 18.1Skill: Knowledge/Comprehension2) The tryptophan operon is a repressible operon that isA) 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: ETopic: Concept 18.1Skill: Knowledge/Comprehension3) Which of the following is a protein produced by a regulatory gene?A) operonB) inducerC) promoterD) repressorE) corepressorAnswer: DTopic: Concept 18.1Skill: Knowledge/Comprehension4) A lack of which molecule would result in the cell's inability to "turn off" genes?A) operonB) inducerC) promoterD) ubiquitinE) corepressorAnswer: ETopic: Concept 18.1Skill: Knowledge/Comprehension1Copyright © 2011 Pearson Education, Inc.5) Which of the following, when taken up by the cell, binds to the repressor so that the repressor no longer binds to the operator?A) ubiquitinB) inducerC) promoterD) repressorE) corepressorAnswer: BTopic: Concept 18.1Skill: Knowledge/Comprehension6) Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation?A) inducerB) promoterC) RNA polymeraseD) transcription factorE) cAMPAnswer: ATopic: Concept 18.1Skill: Knowledge/Comprehension7) A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result inA) 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: ATopic: Concept 18.1Skill: Application/Analysis8) The lactose operon is likely to be transcribed whenA) 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: DTopic: Concept 18.1Skill: Knowledge/Comprehension2Copyright © 2011 Pearson Education, Inc.9) Transcription of the structural genes in an inducible operonA) 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: BTopic: Concept 18.1Skill: Knowledge/Comprehension10) 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: CTopic: Concept 18.1Skill: Knowledge/Comprehension11) Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?A) The repressor protein attaches to the regulator.B) Allolactose binds to the repressor protein.C) Allolactose binds to the regulator gene.D) The repressor protein and allolactose bind to RNA polymerase.E) RNA polymerase attaches to the regulator.Answer: BTopic: Concept 18.1Skill: Knowledge/Comprehension12) Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?A) organizing gene expression so that genes are expressed in a given orderB) allowing each gene to be expressed an equal number of timesC) allowing the organism to adjust to changes in environmental conditionsD) allowing young organisms to respond differently from more mature organismsE) allowing environmental changes to alter the prokaryote's genomeAnswer: CTopic: Concept 18.1Skill: Synthesis/Evaluation3Copyright © 2011 Pearson Education, Inc.13) In response to chemical signals, prokaryotes can do which of the following?A) turn off translation of their mRNAB) alter the level of production of various enzymesC) increase the number and responsiveness of their ribosomesD) inactivate their mRNA moleculesE) alter the sequence of amino acids in certain proteinsAnswer: BTopic: Concept 18.1Skill: Knowledge/Comprehension14) If glucose is available in the environment of E. coli, the cell responds with a very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would you expect to be a measurable effect?A) decreased concentration of the lac enzymesB) increased concentration of the trp enzymesC) decreased binding of the RNA polymerase to sugar metabolism-related promotersD) decreased concentration of alternative sugars in the cellE) increased concentrations of sugars such as arabinose in the cellAnswer: ETopic: Concept 18.1Skill: Synthesis/Evaluation15) In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP?A) increase in glucose and increase in cAMPB) decrease in glucose and increase in cAMPC) increase in glucose and decrease in cAMPD) decrease in glucose and increase in repressorE) decrease in glucose and decrease in repressorAnswer: BTopic: Concept