BIO SCI E109 Test Answers Questions With Complete
Solutions
At beginning of repolarization, what is the most likely state of a
Na+ channel? Correct Answers The activation gate is open and
the inactivation gate is closed
It is most-likely that the inactivation gate is closed because the
membrane at this time is repolarizing.
During depolarization, what best accounts for the change in
slope in Vm as the membrane reaches threshold?
The equilibrium potential for Ca2+ Cl− permeability changes.
Na+ permeability changes
K+ permeability changes
Na+ - K+ - ATPase activity Correct Answers Na+ permeability
changes
Explain the conditions where the membrane potential achieves a
value of +60 mV.
Permeability to Na+.
Permeability to K+.
Permeability to Cl-. Correct Answers Permeability to Na+. -
High
Permeability to K+. - Zero
Permeability to Cl-. Zero
Ground substance may be a liquid.
True
False Correct Answers True
Plasma is a liquid ground substance
,How do positive feedback and negative feedback differ?
Once positive feedback crosses a threshold it will continue
increasing/decreasing at a constant rate.
Positive feedback changes until the set point is achieved.
Negative feedback tends to oscillate around a set point. Correct
Answers Negative feedback tends to oscillate around a set
point.
How does summation in force in a single skeletal muscle fiber
compare to a single twitch in the same fiber?
Greater intracellular calcium.Increased tension.Fewer activated
tropomyosin molecules Correct Answers Greater intracellular
calcium.
How would the equilibrium potential for potassium (EK+)
change if the concentration of that ion increased outside of a
cell?
It would increase
It would decrease
t would stay the same Correct Answers It would decrease
A decrease (i.e. a more negative value) would occur if the
concentration difference between the inside and outside were
greater, whereas the question poses a scenario where they
become less different.
If Muscle A were half the width of Muscle B, by what factor is
the force generated by A different from B, assuming a circular
cross-section for the muscles? Correct Answers 0.25
If the equilibrium potential for a particular ion was found to be
+61 mV and you knew it had a valence of +1 and an
, intracellular concentration of 5 mM, then what would you
predict for the extracellular concentration (in mM)? Correct
Answers 50
If the membrane of the autorhythmic cells in the SA node
became more permeable to potassium ions,
The membrane would depolarize.
The intracellular concentration of calcium ions would increase.
The stroke volume would increase.
The heart rate would decrease.
The heart rate would increase. Correct Answers The heart rate
would decrease
Imagine a group of arterioles that possess receptors but neither
nor receptors. What is the effect of epinephrine release on these
arterioles?
Vasodialation.
Vasoconstriction.
Nothing. Correct Answers Nothing
Imagine that it takes 1 minute for dissolved oxygen to diffuse a
distance of 2 mm through a solution of plasma. How long (in
minutes) would you expect the oxygen to reach 1 cm? Correct
Answers 25???
Imagine the rate of diffusion for a molecule that fluxes across a
1mm x 1mm area of membrane is 5 Moles/second and the
membrane has a thickness of 10 nm.
What rate of diffusion (in Moles/second) would you predict if
the molecular size were to double? Correct Answers 2.5,
Solutions
At beginning of repolarization, what is the most likely state of a
Na+ channel? Correct Answers The activation gate is open and
the inactivation gate is closed
It is most-likely that the inactivation gate is closed because the
membrane at this time is repolarizing.
During depolarization, what best accounts for the change in
slope in Vm as the membrane reaches threshold?
The equilibrium potential for Ca2+ Cl− permeability changes.
Na+ permeability changes
K+ permeability changes
Na+ - K+ - ATPase activity Correct Answers Na+ permeability
changes
Explain the conditions where the membrane potential achieves a
value of +60 mV.
Permeability to Na+.
Permeability to K+.
Permeability to Cl-. Correct Answers Permeability to Na+. -
High
Permeability to K+. - Zero
Permeability to Cl-. Zero
Ground substance may be a liquid.
True
False Correct Answers True
Plasma is a liquid ground substance
,How do positive feedback and negative feedback differ?
Once positive feedback crosses a threshold it will continue
increasing/decreasing at a constant rate.
Positive feedback changes until the set point is achieved.
Negative feedback tends to oscillate around a set point. Correct
Answers Negative feedback tends to oscillate around a set
point.
How does summation in force in a single skeletal muscle fiber
compare to a single twitch in the same fiber?
Greater intracellular calcium.Increased tension.Fewer activated
tropomyosin molecules Correct Answers Greater intracellular
calcium.
How would the equilibrium potential for potassium (EK+)
change if the concentration of that ion increased outside of a
cell?
It would increase
It would decrease
t would stay the same Correct Answers It would decrease
A decrease (i.e. a more negative value) would occur if the
concentration difference between the inside and outside were
greater, whereas the question poses a scenario where they
become less different.
If Muscle A were half the width of Muscle B, by what factor is
the force generated by A different from B, assuming a circular
cross-section for the muscles? Correct Answers 0.25
If the equilibrium potential for a particular ion was found to be
+61 mV and you knew it had a valence of +1 and an
, intracellular concentration of 5 mM, then what would you
predict for the extracellular concentration (in mM)? Correct
Answers 50
If the membrane of the autorhythmic cells in the SA node
became more permeable to potassium ions,
The membrane would depolarize.
The intracellular concentration of calcium ions would increase.
The stroke volume would increase.
The heart rate would decrease.
The heart rate would increase. Correct Answers The heart rate
would decrease
Imagine a group of arterioles that possess receptors but neither
nor receptors. What is the effect of epinephrine release on these
arterioles?
Vasodialation.
Vasoconstriction.
Nothing. Correct Answers Nothing
Imagine that it takes 1 minute for dissolved oxygen to diffuse a
distance of 2 mm through a solution of plasma. How long (in
minutes) would you expect the oxygen to reach 1 cm? Correct
Answers 25???
Imagine the rate of diffusion for a molecule that fluxes across a
1mm x 1mm area of membrane is 5 Moles/second and the
membrane has a thickness of 10 nm.
What rate of diffusion (in Moles/second) would you predict if
the molecular size were to double? Correct Answers 2.5,
