PCB 3023 EXAM 3 QUESTIONS
AND ANSWERS 2026 - 2027
Acetylcholine binds to a GPCR on heart muscle, making the heart
beat slower. The activated receptor stimulates a G protein, which
opens a K+ channel in the plasma membrane, as shown in Figure
16-1. Which of the following would enhance this effect of the
acetylcholine?
A)addition of a high concentration of a nonhydrolyzable analog of
GTP
B) addition of a drug that prevents the α subunit from exchanging
GDP for GTP
C) mutations in the acetylcholine receptor that weaken the
interaction between the receptor and acetylcholine
D) mutations in the acetylcholine receptor that weaken the
interaction between the receptor and the G protein
A)addition of a high concentration of a nonhydrolyzable analog of
GTP
Microtubules are important for transporting cargo in nerve cell
axons, as diagrammed in Figure 17-3. Notice that the two types of
cargo are traveling in opposite directions. Which of the following
statements is likely to be FALSE?
A)The gray cargo is attached to dynein.
B) The black cargo and the gray cargo require ATP hydrolysis for
their motion.
C) The black cargo moving toward the axon terminal contains a
domain that specifically interacts with the tail domain of a
,particular kind of motor.
D) The black cargo and the gray cargo are moving along
microtubules of opposite polarity.
D) The black cargo and the gray cargo are moving along microtubules
of opposite polarity.
Which of the following statements about the function of the
centrosome is FALSE?
A) Microtubules emanating from the centrosome have alternating
polarity such that some have their plus end attached to the
centrosome while others have their minus end attached to the
centrosome.
B)Centrosomes contain hundreds of copies of the γ-tubulin ring
complex important for microtubule nucleation.
C)Centrosomes typically contain a pair of centrioles comprised of
cylindrical arrays of short microtubules.
D)Centrosomes are the major microtubule-organizing center in
animal cells.
A) Microtubules emanating from the centrosome have alternating
polarity such that some have their plus end attached to the centrosome
while others have their minus end attached to the centrosome.
Cell lines A and B both survive in tissue culture containing serum
but do not proliferate. Factor F is known to stimulate
proliferation in cell line A. Cell line A produces a receptor protein
(R) that cell line B does not produce. To test the role of receptor R,
you introduce this receptor protein into cell line B, using
recombinant DNA techniques. You then test all your various cell
lines in the presence of serum for their response to factor F, with
the results summarized in Table 16-1
Which of the following CANNOT be concluded from your results
above?
,A)Binding of factor F to its receptor is required for proliferation
of cell line A.
B)Receptor R binds to factor F to induce cell proliferation in cell
line A.
C)Cell line A expresses a receptor for factor F.
D)Factor F is not required for proliferation in cell line B.
B)Receptor R binds to factor F to induce cell proliferation in cell line
A.
Which statement about microtubules is true?
A)Motor proteins move in a directional fashion along
microtubules by using the inherent structural polarity of a
protofilament.
B)Centromeres on chromosomes nucleate the microtubules of the
mitotic spindle.
C)Because microtubules are subject to dynamic instability, they
are used only for transient structures in a cell.
D)ATP hydrolysis by a tubulin heterodimer is important for
controlling the growth of a microtubule.
A)Motor proteins move in a directional fashion along microtubules by
using the inherent structural polarity of a protofilament.
What is the primary origin of energy for most life on Earth?
The sun.
Which wavelengths of light are most used by plants for
photosynthesis?
Blue and Red.
Why is Photosystem II considered a strong oxidizing agent? It
takes a low energy electron from water
It takes a high energy electron from water
It takes a low energy electron from NADPH
, It takes a high energy electron from NADPH
It returns a high energy electron back from a reduced acceptor
It takes a low energy electron from water.
In the light reactions of photosynthesis, a proton gradient is
generated which drives ATP synthesis. Where do protons become
concentrated in the chloroplast?
stroma
thylakoid space
inner membrane
thylakoid membrane
cytosol
Thylakoid space.
All are examples of proteins that are transported into the nucleus
through nuclear pores except:
DNA and RNA polymerases
transcription factors (TFs)
chromatin assembly proteins (histones)
ATP synthase
lamins
ATP synthase.
Your friend works in a biotechnology company and has
discovered a drug that blocks the ability of Ran to hydrolyze GTP.
What is the most likely effect of this drug on nuclear transport?
A)Nuclear transport receptors would be unable to bind cargo.
B)Nuclear transport receptors would be unable to enter the
nucleus.
C)Nuclear transport receptors would be unable to release their
cargo in the nucleus.
D)Nuclear transport receptors would remain bound to Ran once
they leave the nucleus
AND ANSWERS 2026 - 2027
Acetylcholine binds to a GPCR on heart muscle, making the heart
beat slower. The activated receptor stimulates a G protein, which
opens a K+ channel in the plasma membrane, as shown in Figure
16-1. Which of the following would enhance this effect of the
acetylcholine?
A)addition of a high concentration of a nonhydrolyzable analog of
GTP
B) addition of a drug that prevents the α subunit from exchanging
GDP for GTP
C) mutations in the acetylcholine receptor that weaken the
interaction between the receptor and acetylcholine
D) mutations in the acetylcholine receptor that weaken the
interaction between the receptor and the G protein
A)addition of a high concentration of a nonhydrolyzable analog of
GTP
Microtubules are important for transporting cargo in nerve cell
axons, as diagrammed in Figure 17-3. Notice that the two types of
cargo are traveling in opposite directions. Which of the following
statements is likely to be FALSE?
A)The gray cargo is attached to dynein.
B) The black cargo and the gray cargo require ATP hydrolysis for
their motion.
C) The black cargo moving toward the axon terminal contains a
domain that specifically interacts with the tail domain of a
,particular kind of motor.
D) The black cargo and the gray cargo are moving along
microtubules of opposite polarity.
D) The black cargo and the gray cargo are moving along microtubules
of opposite polarity.
Which of the following statements about the function of the
centrosome is FALSE?
A) Microtubules emanating from the centrosome have alternating
polarity such that some have their plus end attached to the
centrosome while others have their minus end attached to the
centrosome.
B)Centrosomes contain hundreds of copies of the γ-tubulin ring
complex important for microtubule nucleation.
C)Centrosomes typically contain a pair of centrioles comprised of
cylindrical arrays of short microtubules.
D)Centrosomes are the major microtubule-organizing center in
animal cells.
A) Microtubules emanating from the centrosome have alternating
polarity such that some have their plus end attached to the centrosome
while others have their minus end attached to the centrosome.
Cell lines A and B both survive in tissue culture containing serum
but do not proliferate. Factor F is known to stimulate
proliferation in cell line A. Cell line A produces a receptor protein
(R) that cell line B does not produce. To test the role of receptor R,
you introduce this receptor protein into cell line B, using
recombinant DNA techniques. You then test all your various cell
lines in the presence of serum for their response to factor F, with
the results summarized in Table 16-1
Which of the following CANNOT be concluded from your results
above?
,A)Binding of factor F to its receptor is required for proliferation
of cell line A.
B)Receptor R binds to factor F to induce cell proliferation in cell
line A.
C)Cell line A expresses a receptor for factor F.
D)Factor F is not required for proliferation in cell line B.
B)Receptor R binds to factor F to induce cell proliferation in cell line
A.
Which statement about microtubules is true?
A)Motor proteins move in a directional fashion along
microtubules by using the inherent structural polarity of a
protofilament.
B)Centromeres on chromosomes nucleate the microtubules of the
mitotic spindle.
C)Because microtubules are subject to dynamic instability, they
are used only for transient structures in a cell.
D)ATP hydrolysis by a tubulin heterodimer is important for
controlling the growth of a microtubule.
A)Motor proteins move in a directional fashion along microtubules by
using the inherent structural polarity of a protofilament.
What is the primary origin of energy for most life on Earth?
The sun.
Which wavelengths of light are most used by plants for
photosynthesis?
Blue and Red.
Why is Photosystem II considered a strong oxidizing agent? It
takes a low energy electron from water
It takes a high energy electron from water
It takes a low energy electron from NADPH
, It takes a high energy electron from NADPH
It returns a high energy electron back from a reduced acceptor
It takes a low energy electron from water.
In the light reactions of photosynthesis, a proton gradient is
generated which drives ATP synthesis. Where do protons become
concentrated in the chloroplast?
stroma
thylakoid space
inner membrane
thylakoid membrane
cytosol
Thylakoid space.
All are examples of proteins that are transported into the nucleus
through nuclear pores except:
DNA and RNA polymerases
transcription factors (TFs)
chromatin assembly proteins (histones)
ATP synthase
lamins
ATP synthase.
Your friend works in a biotechnology company and has
discovered a drug that blocks the ability of Ran to hydrolyze GTP.
What is the most likely effect of this drug on nuclear transport?
A)Nuclear transport receptors would be unable to bind cargo.
B)Nuclear transport receptors would be unable to enter the
nucleus.
C)Nuclear transport receptors would be unable to release their
cargo in the nucleus.
D)Nuclear transport receptors would remain bound to Ran once
they leave the nucleus
