Question 1

According to the equation expressed as Ohm's law,which of these would cause the greatest increase in current?
A)Doubling both voltage and resistance
B)Reducing both voltage and resistance by half
C)Doubling voltage and reducing resistance by half
D)Reducing voltage by half and doubling resistance
E)Quadrupling both voltage and resistance

Accepted Answer

Ohm's law states that current (I) is directly proportional to voltage (V) and inversely proportional to resistance (R), or I = V/R. In order to increase current, we need to increase the voltage or decrease the resistance, or both. Option C, where we double the voltage and reduce the resistance by half, is the only choice where we are doing both. This will result in a four-fold increase in current.

Question 2

The membrane potential of most neurons at rest is
A)equal to the equilibrium potential for potassium.
B)equal to the equilibrium potential for sodium.
C)slightly more negative than the equilibrium potential of potassium ion.
D)more positive than the equilibrium potential for potassium.
E)more positive than the equilibrium potential for sodium.

Accepted Answer

The resting membrane potential of most neurons is slightly more positive than the equilibrium potential for potassium due to the influence of other ions, primarily sodium, which has a less negative equilibrium potential.

Question 3

Which of these would occur if the concentration of ATP were depleted in a typical nerve cell?
A)Resting membrane potential would become more negative.
B)Resting membrane potential would become less negative.
C)The concentration gradient for Na⁺ would remain the same.
D)The resting membrane potential would eventually become positive inside with respect to outside.
E)There would be no change in the resting membrane potential.

Accepted Answer

ATP is required for the function of the Na+/K+ ATPase pump, which maintains the ionic concentration gradients across the cell membrane. If ATP concentration is depleted, the pump cannot function effectively, resulting in a buildup of intracellular Na+ and extracellular K+. This disturbs the resting membrane potential, making it less negative (closer to zero) and more prone to depolarization.

Question 4

Compartments A and B are separated by a membrane that is permeable to K⁺ but not to Na⁺ or Cl⁻.At time zero,a solution of KCl is poured into compartment A and an equally concentrated solution of NaCl is poured into compartment B.Which would be true once equilibrium is reached?
A)The concentration of Na⁺ in A will be higher than it was at time zero.
B)Diffusion of K⁺ from A to B will be greater than the diffusion of K⁺ from B to A.
C)There will be a potential difference across the membrane,with side B negative relative to side A.
D)The electrical potential difference and diffusion potential due to the concentration gradient for K⁺ will be equal in magnitude and opposite in direction.
E)The concentration of Cl⁻ will be higher in B than it was at time zero.

Accepted Answer

The answer of Compartments A and B are separated by...

Question 5

Which is TRUE about typical,resting neurons?
A)The plasma membrane is most permeable to sodium ions.
B)The concentration of sodium ion is greater inside the cell than outside.
C)The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions.
D)The plasma membrane is completely impermeable to sodium ions.
E)The plasma membrane is completely impermeable to potassium ions.

Accepted Answer

Resting neurons have a higher permeability to potassium ions compared to sodium ions. This is due to the presence of more potassium leak channels in the plasma membrane of the neuron. Additionally, the concentration of potassium ions is higher inside the cell compared to outside, which creates an electrochemical gradient that drives the efflux of potassium ions out of the cell. The efflux of potassium ions also contributes to the negative resting membrane potential of the neuron.

Question 6

Which of the following is NOT true about axon transport?
A)It refers to the passage of materials from the cell body of a neuron to the axon terminals.
B)It refers to the passage of materials from axon terminals to the cell body of a neuron.
C)It refers to the transport of materials from the inside to the outside across the axonal membrane.
D)It is especially important for maintaining the integrity of neurons with long axons.

Accepted Answer

Axon transport does not refer to the transport of materials from inside to outside across the axonal membrane; rather, it refers to the movement of materials in the opposite direction between the cell body and axon terminals.

Question 7

Which is FALSE about neurons?
A)A given neuron can be either a presynaptic neuron or a postsynaptic neuron.
B)An individual  neuron can receive information from multiple other neurons.
C)An individual neuron can transmit information to multiple other neurons.
D)A neuron can simultaneously release more than one type of neurotransmitter.
E)A neuron receives information on its axons and delivers it to other neurons through its dendrites.

Accepted Answer

Neurons receive information on their dendrites and transmit it to other neurons through their axons. Therefore, statement E is false. The other statements are true.

Question 8

Which is TRUE about the Na⁺,K⁺ ATPase pump in neurons?
A)It generates a small electrical potential such that the inside is made negative with respect to the outside.
B)It maintains a concentration gradient for K⁺ such that diffusion forces favor movement of K⁺ into the cell.
C)It maintains an electrical gradient at the equilibrium potential of K⁺.
D)It transports equal numbers of sodium and potassium ions with each pump cycle.
E)It pumps 3 Na⁺ ions into the cell for every 2 K⁺ ions it pumps out.

Accepted Answer

The Na⁺,K⁺ ATPase pump generates a small electrical potential by pumping 3 Na⁺ ions out of the cell and 2 K⁺ ions into the cell for each cycle, making the inside of the cell negative relative to the outside. This is crucial for maintaining the resting membrane potential in neurons.

Question 9

If there was an increased concentration of K⁺ outside of the neuron,which would be TRUE?
A)Neurons would spontaneously depolarize.
B)Neurons would spontaneously hyperpolarize.
C)The potassium equilibrium potential of nerve cells would become more negative. 
D)The sodium equilibrium potential would become less positive.
E)During an action potential,the neuron would repolarize slowly or stay depolarized.

Accepted Answer

The answer of If there was an increased concentration of...

Question 10

Which is NOT an example of a graded potential?
A)A receptor potential in a sensory receptor cell
B)A depolarizing excitatory postsynaptic potential (EPSP)
C)A hyperpolarizing inhibitory postsynaptic potential (IPSP)
D)A depolarizing pacemaker potential
E)A depolarizing action potential

Accepted Answer

Graded potentials are changes in membrane potential that vary in size and can be either hyperpolarizing or depolarizing. An action potential, on the other hand, is an all-or-nothing event that does not vary in size and is not a graded potential.

Question 11

The difference in electrical charge between two points
A)is called the potential difference between those points.
B)is called the diffusion potential between those points.
C)is called the current,and is expressed in the units of millimoles.
D)is the same for all ions.

Accepted Answer

The difference in electrical charge between two points is called potential difference. It is measured in volts and determines the direction and strength of electrical current flow. The other options are incorrect - diffusion potential refers to the difference in ion concentration across a membrane, current is the flow of electrons, and the difference in electrical charge is not the same for all ions.

Question 12

Which of the following statements concerning the permeability of a typical neuron membrane at rest is TRUE?
A)The permeability to Na⁺ is much greater than the permeability to K⁺.
B)All of the K⁺ channels in the membrane are open.
C)The voltage-gated Na⁺ channels are in the inactivated state.
D)Most of the voltage-gated Na⁺ channels are in the closed state.
E)There is equal permeability to Na⁺ and K⁺.

Accepted Answer

At rest, most of the voltage-gated Na⁺ channels are in the closed state and only a few are in the inactive state. This means that the permeability to Na⁺ is much lower than the permeability to K⁺.

Question 13

Some viruses can hide from the immune system by retrograde transport from axonal terminals in the skin to the cell body of a neuron.  Which of the following might be an effective preventative therapy?
A)A kinesin inhibitor
B)A dynein inhibitor
C)Actin polymerization inhibitor
D)Myosin inhibitor
E)None of these would prevent this type of infection

Accepted Answer

Retrograde transport from axonal terminals to the cell body of a neuron is mediated by dynein motor proteins. Therefore, inhibiting dynein would prevent the virus from spreading to the cell body and hiding from the immune system.

Question 14

Which of the following is NOT true of glial cells?
A)They form the myelin for axons.
B)They are outnumbered 10 to 1 by neurons in the nervous system.
C)They deliver fuel molecules to neurons and remove the waste products of metabolism.
D)They are important for the growth and development of the nervous system.
E)They regulate the composition of the extracellular fluid in the CNS.

Accepted Answer

Glial cells actually outnumber neurons in the nervous system by a factor of 10 to 50, depending on the region of the brain. Therefore, statement B is NOT true of glial cells.

Question 15

Two neighboring neurons are at rest.  Neuron A has a resting membrane potential of -80mV,Neuron B has a resting membrane potential of -70mV. Which is likely to be TRUE?
A)Neuron A has more K⁺ channels open than Neuron B.
B)Neuron B has more K⁺ channels open than Neuron A.
C)Neuron A has more Na⁺ channels open than Neuron B.
D)Neuron B has more Na⁺ channels open than Neuron A.
E)None of the answer choices are correct.

Accepted Answer

Neuron A, with a more negative resting membrane potential, likely has more K⁺ channels open. This allows more potassium ions to exit the cell, making the inside more negative compared to Neuron B.

Question 16

You are studying a cross-sectional tissue slice of a nerve using a transmission electron microscope.  You find an area where there appears to be a small amount of cytoplasm surrounded by about 100 layers of stacked cell membranes.You conclude that you have found
A)a neuron cell body.
B)a synapse.
C)an unmyelinated axon.
D)a myelinated axon.

Accepted Answer

The presence of about 100 stacked layers of cell membranes indicates myelin, which is characteristic of a myelinated axon. Additionally, the small amount of cytoplasm suggests that this area represents the axon, rather than the cell body or synapse.

Question 17

Which is TRUE about the resting membrane potential?
A)It requires very few ions to be distributed unevenly.
B)It has the same value in all cells.
C)It is oriented so that the cell's interior is positive with respect to the extracellular fluid.
D)Only nerve and muscle cells have a potential difference across the membrane at rest.
E)It is not altered by changing concentration gradients of permeating ions.

Accepted Answer

The resting membrane potential is established with relatively few ions needing to be distributed unevenly across the cell membrane, creating a voltage difference. This is due to the cell membrane's selective permeability to certain ions and the action of ion pumps.

Question 18

An action potential in a neuronal membrane differs from a graded potential in that
A)an action potential requires the opening of Ca²⁺ channels,whereas a graded potential does not.
B)an action potential is propagated without decrement,whereas a graded potential decrements with distance.
C)an action potential has a threshold,whereas a graded potential is an all-or-none phenomenon.
D)movement of Na⁺ and K⁺ across cell membranes mediate action potentials,while graded potentials do not involve movement of Na⁺ and K⁺.
E)action potentials vary in size with the size of a stimulus,while graded potentials do not.

Accepted Answer

Action potentials propagate along the neuron without decreasing in strength, regardless of distance, due to the regenerative mechanism of ion channel opening. In contrast, graded potentials decrease in strength as they spread away from the point of origin, because they do not have this regenerative property.

Question 19

Which is FALSE about the equilibrium potential of a given ion across a membrane?
A)It is a function of the concentration of that ion on both sides of the membrane.
B)It is the potential at which there is no net movement of that ion across the membrane.
C)It is the potential difference across the membrane at which an electric force favoring movement of the ion in one direction is equal in magnitude and opposite in direction to the diffusion force provided by the concentration difference of the ion across the membrane.
D)A permeable ion will move in the direction that will tend to bring the membrane potential toward that ion's equilibrium potential.
E)An anion that is in higher concentration inside the cell than outside the cell will have a negative equilibrium potential.

Accepted Answer

An anion that is in higher concentration inside the cell than outside the cell will have a positive equilibrium potential (not a negative one). Therefore, statement E is false.

Question 20

Which of the following is TRUE about the concentration gradient of Na⁺ in a neuron at rest?
A)It favors its movement into the cell at the resting membrane potential.
B)It favors its movement out of the cell at the resting membrane potential.
C)It is equal and opposite to the electrical potential acting on Na⁺ at the resting membrane potential.
D)It is in the same direction as the diffusion potential due to the concentration gradient for K⁺.
E)It favors movement of Na⁺ in the opposite direction as the electrical potential acting on Na⁺ at the resting membrane potential.

Accepted Answer

EAt the resting membrane potential, the concentration gradient of Na⁺ favors its movement into the cell because the concentration of Na⁺ is higher outside the cell than inside. Additionally, the electrical potential inside the neuron is negative relative to the outside, which also attracts the positively charged Na⁺ ions into the cell, making statement E true as it indicates that the movement favored by the concentration gradient (into the cell) is in the opposite direction to that favored by the electrical potential (which also attracts Na⁺ into the cell).

Quiz 6: Neuronal Signaling and the Structure of the Nervous System

According to the equation expressed as Ohm's law,which of these would cause the greatest increase in current?

The membrane potential of most neurons at rest is

Which of these would occur if the concentration of ATP were depleted in a typical nerve cell?

Compartments A and B are separated by a membrane that is permeable to K⁺ but not to Na⁺ or Cl⁻.At time zero,a solution of KCl is poured into compartment A and an equally concentrated solution of NaCl is poured into compartment B.Which would be true once equilibrium is reached?

Which is TRUE about typical,resting neurons?

Which of the following is NOT true about axon transport?

Which is FALSE about neurons?

Which is TRUE about the Na⁺,K⁺ ATPase pump in neurons?

If there was an increased concentration of K⁺ outside of the neuron,which would be TRUE?

Which is NOT an example of a graded potential?

The difference in electrical charge between two points

Which of the following statements concerning the permeability of a typical neuron membrane at rest is TRUE?

Some viruses can hide from the immune system by retrograde transport from axonal terminals in the skin to the cell body of a neuron. Which of the following might be an effective preventative therapy?

Which of the following is NOT true of glial cells?

Two neighboring neurons are at rest. Neuron A has a resting membrane potential of -80mV,Neuron B has a resting membrane potential of -70mV. Which is likely to be TRUE?

You are studying a cross-sectional tissue slice of a nerve using a transmission electron microscope. You find an area where there appears to be a small amount of cytoplasm surrounded by about 100 layers of stacked cell membranes.You conclude that you have found

Which is TRUE about the resting membrane potential?

An action potential in a neuronal membrane differs from a graded potential in that

Which is FALSE about the equilibrium potential of a given ion across a membrane?

Which of the following is TRUE about the concentration gradient of Na⁺ in a neuron at rest?