BIO 203 EXAM 4 QUESTION AND CORRECT ANSWER NEWEST
2025 A+ GUIDE 100% COMPLETE
Question 1
Which of the following is a protein produced by a regulatory gene?
A) operon
B) inducer
C) promoter
D) repressor
Question 2
A lack of which molecule would result in a cell's inability to "turn off" genes?
A) operon
B) inducer
C) promoter
D) corepressor
Question 3
Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer
binds to the operator?
A) inducer
B) promoter
C) repressor
D) corepressor
,Question 4
Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its
conformation?
A) inducer
B) promoter
C) transcription factor
D) cAMP
Question 5
A mutation that inactivates a 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) continuous translation of the mRNA because of alteration of its structure
Question 6
The lactose operon is likely to be transcribed when _____.
A) there is more glucose in the cell than lactose
B) there is glucose but no lactose in the cell
C) the cyclic AMP and lactose levels are both high within the cell
D) the cAMP level is high and the lactose level is low
Question 7
Transcription of 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
Question 8
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 must not occupy the promoter, and the repressor must be inactive.
Question 9
Altering patterns of gene expression in prokaryotes would most likely serve an organism's survival by
_____.
A) organizing gene expression, so that genes are expressed in a given order
B) allowing each gene to be expressed an equal number of times
C) allowing an organism to adjust to changes in environmental conditions
D) allowing environmental changes to alter a prokaryote's genome
Question 10
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 activity in stimulating
transcription?
A) an increase in glucose and an increase in cAMP
B) a decrease in glucose and an increase in cAMP
C) an increase in glucose and a decrease in cAMP
D) a decrease in glucose and a decrease in the repressor
Question 11
There is a mutation in the repressor that results in a molecule known as a super-repressor because it
represses the lac operon permanently. Which of these would characterize such a mutant?
A) It cannot bind to the operator.
, B) It cannot make a functional repressor.
C) It cannot bind to the inducer.
D) It makes a repressor that binds CAP.
Question 12
If she moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene
and the permease (lacY) gene, which of the following would be likely?
A) The three structural genes will be expressed normally.
B) RNA polymerase will no longer transcribe permease.
C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated.
D) Beta galactosidase will not be produced.
Question 13
If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the
following would likely occur when the cell is exposed to lactose?
A) The inducer will no longer bind to the repressor.
B) The repressor will no longer bind to the operator.
C) The operon will never be transcribed.
D) The structural genes will be transcribed continuously.
Question 14
If she moves the repressor gene (lacI), along with its promoter, to a position at some several thousand
base pairs away from its normal position, we would expect the _____.
A) repressor will no longer bind to the operator
B) repressor will no longer bind to the inducer
C) lac operon will be expressed continuously
D) lac operon will function normally
Question 15
2025 A+ GUIDE 100% COMPLETE
Question 1
Which of the following is a protein produced by a regulatory gene?
A) operon
B) inducer
C) promoter
D) repressor
Question 2
A lack of which molecule would result in a cell's inability to "turn off" genes?
A) operon
B) inducer
C) promoter
D) corepressor
Question 3
Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer
binds to the operator?
A) inducer
B) promoter
C) repressor
D) corepressor
,Question 4
Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its
conformation?
A) inducer
B) promoter
C) transcription factor
D) cAMP
Question 5
A mutation that inactivates a 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) continuous translation of the mRNA because of alteration of its structure
Question 6
The lactose operon is likely to be transcribed when _____.
A) there is more glucose in the cell than lactose
B) there is glucose but no lactose in the cell
C) the cyclic AMP and lactose levels are both high within the cell
D) the cAMP level is high and the lactose level is low
Question 7
Transcription of 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
Question 8
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 must not occupy the promoter, and the repressor must be inactive.
Question 9
Altering patterns of gene expression in prokaryotes would most likely serve an organism's survival by
_____.
A) organizing gene expression, so that genes are expressed in a given order
B) allowing each gene to be expressed an equal number of times
C) allowing an organism to adjust to changes in environmental conditions
D) allowing environmental changes to alter a prokaryote's genome
Question 10
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 activity in stimulating
transcription?
A) an increase in glucose and an increase in cAMP
B) a decrease in glucose and an increase in cAMP
C) an increase in glucose and a decrease in cAMP
D) a decrease in glucose and a decrease in the repressor
Question 11
There is a mutation in the repressor that results in a molecule known as a super-repressor because it
represses the lac operon permanently. Which of these would characterize such a mutant?
A) It cannot bind to the operator.
, B) It cannot make a functional repressor.
C) It cannot bind to the inducer.
D) It makes a repressor that binds CAP.
Question 12
If she moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene
and the permease (lacY) gene, which of the following would be likely?
A) The three structural genes will be expressed normally.
B) RNA polymerase will no longer transcribe permease.
C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated.
D) Beta galactosidase will not be produced.
Question 13
If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the
following would likely occur when the cell is exposed to lactose?
A) The inducer will no longer bind to the repressor.
B) The repressor will no longer bind to the operator.
C) The operon will never be transcribed.
D) The structural genes will be transcribed continuously.
Question 14
If she moves the repressor gene (lacI), along with its promoter, to a position at some several thousand
base pairs away from its normal position, we would expect the _____.
A) repressor will no longer bind to the operator
B) repressor will no longer bind to the inducer
C) lac operon will be expressed continuously
D) lac operon will function normally
Question 15
