ASU BIO 340 EXAM 3 QUESTIONS WITH
CORRECT ANSWERS GRADED TO A+
2025-2026
What will be the effect on transcription when an inhibitor is in play?
A. Allow transcription B. Prevent transcription CORRECT ANSWER
B EXPLANATIONAn inhibitor prevents activator from binding to DNA; activators are used in positive
regul ation (increasing transcription) -
thus, the inhibitor prevents the activator from positive regulating (increasing) transcription.
What will be the effect on transcription when an inducer is in play?
A. Allow transcription B. Prevent transcription CORRECT ANSWER
ABEXPLANATIONWhen an inducer is in play, it will allow transcription.
For a gene under positive control, which of the following would prevent transcription?
A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor CORRECT ANSWER
E EXPLANATIONPositive regulation includes activators (affected by effectors and inhibitors);
inhibitors pre vent activator from binding to DNA, thus preventing transcription.
For a gene under negative control, which of the following would you expect to find bound to the repress
or if there is active transcription? A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor -
correct answer-
C EXPLANATIONIn negative regulation, there are repressors (affected by correpressors and
inducers). If th ere were a corepressor, the repressor would successfully bind to the operator and
prevent transcription. Inducers, however, prevent the binding of the repressor -
thus causing a prevention of it doing its job, and allowing transcription.
Which molecule serves as the inducer for the lac operon?
A. cAMP B. Glucose C. Lactose D. Allolactose CORRECT ANSWER
D EXPLANATIONAllolactose is the molecule that binds to repressor protein, making it unable to bind
to th e operator.
Which of the following conditions will resultBin the greatest levels of transcription of the lac operon?
A. Lactose absent, glucose absent B. Lactose absent, glucose present C. Lactose present, glucose present
D. Lactose present, glucose absen CORRECT ANSWER
, D EXPLANATIONFrom the perspective of the cell, it is most efficient to repress expression of the genes
all
CORRECT ANSWERS GRADED TO A+
2025-2026
What will be the effect on transcription when an inhibitor is in play?
A. Allow transcription B. Prevent transcription CORRECT ANSWER
B EXPLANATIONAn inhibitor prevents activator from binding to DNA; activators are used in positive
regul ation (increasing transcription) -
thus, the inhibitor prevents the activator from positive regulating (increasing) transcription.
What will be the effect on transcription when an inducer is in play?
A. Allow transcription B. Prevent transcription CORRECT ANSWER
ABEXPLANATIONWhen an inducer is in play, it will allow transcription.
For a gene under positive control, which of the following would prevent transcription?
A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor CORRECT ANSWER
E EXPLANATIONPositive regulation includes activators (affected by effectors and inhibitors);
inhibitors pre vent activator from binding to DNA, thus preventing transcription.
For a gene under negative control, which of the following would you expect to find bound to the repress
or if there is active transcription? A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor -
correct answer-
C EXPLANATIONIn negative regulation, there are repressors (affected by correpressors and
inducers). If th ere were a corepressor, the repressor would successfully bind to the operator and
prevent transcription. Inducers, however, prevent the binding of the repressor -
thus causing a prevention of it doing its job, and allowing transcription.
Which molecule serves as the inducer for the lac operon?
A. cAMP B. Glucose C. Lactose D. Allolactose CORRECT ANSWER
D EXPLANATIONAllolactose is the molecule that binds to repressor protein, making it unable to bind
to th e operator.
Which of the following conditions will resultBin the greatest levels of transcription of the lac operon?
A. Lactose absent, glucose absent B. Lactose absent, glucose present C. Lactose present, glucose present
D. Lactose present, glucose absen CORRECT ANSWER
, D EXPLANATIONFrom the perspective of the cell, it is most efficient to repress expression of the genes
all
