1 | Page
ASU BIO 340 EXAM 3 2026/2027
ACTUAL QUESTIONS WITH
VERIFIED ANSWERS.
What will be the effect on transcription when an inhibitor is in
play?
A. Allow transcription B. Prevent transcription - ANSWER-B
Explanation: An inhibitor prevents activator from binding to
DNA; activators are used in positive regulation (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 - ANSWER-A
Explanation: When 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
- ANSWER-E Explanation: Positive regulation includes
activators (affected by effectors and inhibitors); inhibitors
, 2 | Page
prevent 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 repressor if there is active
transcription? A. Repressor B. Corepressor C. Inducer D.
Effector E. Inhibitor - ANSWER-C Explanation: In negative
regulation, there are repressors (affected by correpressors and
inducers). If there 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 - ANSWER-D
Explanation: Allolactose is the molecule that binds to repressor
protein, making it unable to bind to the operator.
Which of the following conditions will result in 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 - ANSWER-D Explanation: From the
perspective of the cell, it is most efficient to repress expression
ASU BIO 340 EXAM 3 2026/2027
ACTUAL QUESTIONS WITH
VERIFIED ANSWERS.
What will be the effect on transcription when an inhibitor is in
play?
A. Allow transcription B. Prevent transcription - ANSWER-B
Explanation: An inhibitor prevents activator from binding to
DNA; activators are used in positive regulation (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 - ANSWER-A
Explanation: When 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
- ANSWER-E Explanation: Positive regulation includes
activators (affected by effectors and inhibitors); inhibitors
, 2 | Page
prevent 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 repressor if there is active
transcription? A. Repressor B. Corepressor C. Inducer D.
Effector E. Inhibitor - ANSWER-C Explanation: In negative
regulation, there are repressors (affected by correpressors and
inducers). If there 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 - ANSWER-D
Explanation: Allolactose is the molecule that binds to repressor
protein, making it unable to bind to the operator.
Which of the following conditions will result in 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 - ANSWER-D Explanation: From the
perspective of the cell, it is most efficient to repress expression
