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There are 25 questions in this Biology 3058 exam.
All questions are "A, B, C, D, E, F, G, H" questions worth one point each.
There is a total of 25 points in this exam. Fill in your answers on the separate answer sheet.
The format for this exam is:
Fill in A if A is the only correct answer.
Fill in B if B is the only correct answer.
Fill in C if C is the only correct answer.
Fill in D if both A and B are correct (and C is NOT correct).
Fill in E if both A and C are correct (and B is NOT correct).
Fill in F if both B and C are correct (and A is NOT correct).
Fill in G if A and B and C are all correct.
Fill in H if none of the above is correct (A is NOT correct, B is NOT correct, and C is NOT
correct).
ONLY MARK ONE LETTER PER QUESTION.
You may keep the question sheets.
Use a dark (black or blue) pencil or dark (black or blue) pen to fill in the answers.
DO NOT USE A RED PEN; DO NOT USE A RED PENCIL.
- A complete motor neuron is removed from a frog and placed in a large volume of normal
physiological saline. The neuron is healthy; it has a stable resting voltage of
- 70 millivolts. It is not producing any action potentials; its threshold for an action
potential is - 50 millivolts. The only ligand-gated Receptors in the neuron's plasma
membrane are AMPA Receptors, GABA B
Receptors, and glycine Receptors. The
equilibrium potential for chloride ions is - 70 millivolts, the equilibrium potential for
potassium ions is - 90 millivolts, and the equilibrium potential for sodium ions is
+60 millivolts.
A. The addition of GABA to the physiological saline will lead to an increase in the
chloride conductance of the plasma membrane of the neuron.
B. The addition of glycine and GABA to the physiological saline will lead to a
decrease in the amount of intracellular chloride and a decrease in the amount of
intracellular potassium.
C. The addition of glycine and glutamate to the physiological saline will lead to an
increase in the amount of intracellular chloride, an increase in the amount of
intracellular sodium, and an increase in the amount of intracellular potassium.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following occur in response to an increase in the length of the right knee
extensors in response to a quick tap applied to the right patellar tendon? An increase in
the amount of
A. glutamate released from central axon terminals of IA muscle-spindle stretch
receptor neurons whose peripheral axon terminals are in the right knee extensor
muscle.
B. glutamate bound to AMPA Receptors in the plasma membranes of the muscle
fibers of the right knee extensor muscle.
C. potassium conductance in the plasma membranes of dendrites of right knee
extensor motor neurons located in the right side of the spinal cord.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Consider Neuron B in the frog central nervous system whose plasma membrane has a
previously unknown channel that is selectively conductive to a newly discovered trivalent
anion named TVA with a valence of - 3. The threshold for an action potential in Neuron B
is - 65 millivolts and the resting potential for Neuron B is - 70 millivolts. The TVA channel
in Neuron B is part of an ionotropic receptor with an extracellular binding site for the
newly discovered ligand LGD. When LGD binds to its binding site, there is an increase
in the TVA conductance of Neuron B. Neuron A synapses onto Neuron B. Neuron A's
neurotransmitter is LGD.
A. Consider the situation when the extracellular concentration of TVA is
10,000 times greater than the intracellular concentration of TVA. In response to
an action potential in Neuron A, there will be: a decrease in the membrane
voltage of Neuron B; an inhibitory postsynaptic potential in Neuron B; and an
increase in the amount of intracellular TVA in Neuron B.
B. Consider the situation when the extracellular concentration of TVA is 1,000 times
greater than the intracellular concentration of TVA. In response to an action
potential in Neuron A, there will be: an increase in the membrane voltage of
Neuron B; an excitatory postsynaptic potential in Neuron B; and a decrease in
the amount of intracellular TVA in Neuron B.
C. Consider the situation when the extracellular concentration of TVA is 100 times
greater than the intracellular concentration of TVA. In response to an action
potential in Neuron A, there will be: an increase in the membrane voltage of
Neuron B; an excitatory postsynaptic potential in Neuron B; and a decrease in
the amount of intracellular TVA in Neuron B.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Neuron A is a healthy neuron with all the usual ion channels. When at rest with a
membrane voltage of R millivolts, neuron A produces no action potentials. The voltage
threshold for an action potential in neuron A is T millivolts. T is greater than R; T is less
than zero. In addition, neuron A's membrane includes the membrane-spanning
molecule Z with an ion channel that opens when neurotransmitter Y binds to the
Y receptor site on the extracellular surface of Z. The Nernst equilibrium potential for Z's
ion channel is E millivolts. Neuron B synapses on neuron A; neuron B's neurotransmitter
is neurotransmitter Y. Which of the following statements are true when neuron A is
initially at rest and neuron B releases neurotransmitter Y?
A. If the value of R is less than E, if the value of E is less than T, and if chloride is
the only ion that passes through open Z channels, then Y's binding to its receptor
site on Z in neuron A produces an increase in the amount of intracellular chloride
ions in neuron A.
B. If the value of E is zero and if both sodium ions and potassium ions pass through
open Z channels, then Y's binding to its receptor site on Z in neuron A produces
no change in the amount of intracellular sodium ions in neuron A.
C. If the value of E is equal to R, and if chloride is the only ion that passes through
open Z channels, then Y's binding to its receptor site on Z in neuron A produces
no change in the amount of intracellular chloride ions in neuron A.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Consider Neuron B in the frog central nervous system whose plasma membrane has a
newly discovered ligand-gated ionotropic receptor, named the LIGD receptor. The
channel in the same molecular complex as the LIGD receptor is termed the LIGD
receptor channel. The Nernst equilibrium potential for sodium in Neuron B is 0 mV, and
the Nernst equilibrium potential for potassium in Neuron B is - 100 mV. The threshold for
an action potential in Neuron B is - 60 mV and the resting potential for Neuron B is
- 75 mV. LIGD is an agonist for the ligand-gated ionotropic receptor. When LIGD binds
to its binding site, there is an increase in conductance of the LIGD receptor channel.
Neuron A synapses onto Neuron B. Neuron A's transmitter is LIGD.
A. Consider the situation that when the LIGD receptor channel is open in Neuron B,
it is permeable to both sodium and potassium. For this situation, when open, it is
permeable to no other ions. For this situation, when open, its potassium
conductance equals two times its sodium conductance. For this situation, in
response to an action potential in Neuron A, then there will be a voltage increase
and an excitatory postsynaptic potential in Neuron B.
B. Consider the situation that when the LIGD receptor channel is open in Neuron B,
it is permeable to sodium only. For this situation, when open, it is permeable to
no other ions. For this situation, in response to an action potential in Neuron A,
then there will be a voltage increase and an excitatory postsynaptic potential in
Neuron B.
C. Consider the situation that when the LIGD receptor channel is open in Neuron B,
it is permeable to both sodium and potassium. For this situation, when open, it is
permeable to no other ions. For this situation, when open, its potassium
conductance equals three times its sodium conductance. For this situation, in
response to an action potential in Neuron A, then there will be a voltage
decrease and an inhibitory postsynaptic potential in Neuron B.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following is an agonist that binds to a receptor site that is part of a
ligand-gated metabotropic receptor?
A. Muscarine.
B. GABA.
C. ACh (acetylcholine).
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following is an antagonist that binds to a receptor site that is part of a
ligand-gated ionotropic receptor?
A. Curare.
B. Muscarine.
C. Strychnine.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following is true for both the GABA A
receptor and the GABA B
receptor?
A. Each type of receptor is always linked to its associated ion channel via a
G-protein.
B. GABA is an antagonist for each type of receptor.
C. A chloride channel is associated with each type of receptor.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- A healthy skeletal muscle fiber is isolated and has no external forces on it. It has normal
intracellular levels of ATP and is bathed in physiological saline. Which of the following
occur in response to an action potential in the plasma membrane of the muscle fiber?
A. An increase in the amount of calcium ions bound to troponin.
B. An increase in the amount of Dihydropyridine (DHP) bound to DHP Receptors in
the membranes of the sarcoplasmic reticulum.
C. An increase in the calcium conductance of the channel associated with the
Ryanodine Receptor in the membranes of the transverse tubules.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following is true in a skeletal muscle?
A. The binding of calcium to tropomyosin causes movement of troponin so that the
troponin no longer blocks binding sites on actin for energized myosin heads.
B. The head of a myosin molecule is activated (energized) during the hydrolysis of
GTP (which is bound to the myosin head) to GDP and P i
C. During rigor mortis, myosin heads that are already attached to actin molecules
remain attached to the actin molecules due to no ATP or very low levels of ATP
in the cytosol of the muscle.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- In the sarcomere of a skeletal muscle, there are
A. myosin molecules in the I band.
B. both tropomyosin and myosin molecules in the region of the A band that is not in
the H zone.
C. actin molecules in the H zone.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following serves as an effector, or as part of an effector, in a negative
feedback system?
A. Action potentials in parasympathetic neurons that release ACh (acetylcholine)
near SA node cells of the heart.
B. Action potentials in ventricular muscle cells of the heart.
C. Action potentials in SA node cells of the heart.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- At 1:00 AM, person X's blood pressure is equal to the blood pressure set point. At
1:01 AM, there is an increase in the firing rate of carotid artery baroreceptors.
A. This will lead to a decrease in the amount of NE (norepinephrine) released near
the SA node of the heart.
B. This will lead to a decrease in the heart rate.
C. This will lead to a decrease in the diameter of the arterioles.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- The axons of all the baroreceptors in the body were destroyed at 2 AM. All else is
normal. Which of the following statements is true for the system at 2:10 AM when
compared to their values at 1:50 AM?
A. Blood pressure will decrease.
B. Arteriolar diameter will decrease.
C. The firing rate of parasympathetic neurons innervating the SA node of the heart
will decrease.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following is true for SA node cardiac muscle cells?
A. An increase in the binding of norepinephrine to alpha-adrenergic receptors in
SA node cells will lead to an increase in intracellular levels of cAMP in these
cells.
B. An increase in intracellular levels of cAMP in SA node cells will lead to an
increase in the amount of time between two successive action potentials in SA
node cells.
C. An increase in the binding of acetylcholine to nicotinic ACh receptors in SA node
cells will lead to a decrease in heart rate.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following will lead to a decrease of total peripheral resistance?
A. An increase in the diameter of every arteriole.
B. A decrease of firing rate in all the sympathetic neurons that innervate smooth
muscles that surround arterioles.
C. A decrease in the firing frequency of all the carotid artery baroreceptors.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- A decrease in parasympathetic discharge to the heart leads to
A. an increase in the conductance of F-channels in SA node cells.
B. an increase in the conductance of potassium channels associated with
muscarinic ACh receptors in SA node cells.
C. an increase in the amount of ACh (acetylcholine) released near SA node cells of
the heart.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
- Which of the following are true for the SA node cardiac muscle cells?
A. F-channel conductance will increase only when SA node cell membrane voltage
is greater than - 40mv.
B. An increase in the binding of acetylcholine to nicotinic ACh receptors in the
plasma membranes of the SA node cells will lead to a decrease in heart rate.
C. An increase in the binding of norepinephrine to beta-adrenergic receptors in the
plasma membranes of SA node cells will lead to an increase in heart rate.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
2 5. The AV node of a mammalian heart is destroyed.
A. The firing rate of the cells in the right bundle branch will be the same as the firing
rate of the cells in the left bundle branch.
B. A depolarization in a cell in the left atrium will cause a depolarization of a cell in
the left ventricle.
C. The rate of ventricular contractions will be lower than the rate of atrial
contractions.
D. A and B.
E. A and C.
F. B and C.
G. A, B, and C.
H. None of the above.
