Question 1

The Nernst equation specifies the equilibrium potential for a particular ion. This equilibrium potential is a function of ________.

Accepted Answer

A)  hydrostatic pressure 
B)  ion concentration gradient 
C)  osmotic gradient 
D)  temperature (thermal) gradient 
A)  hydrostatic pressure 
B)  ion concentration gradient 
C)  osmotic gradient 
D)  temperature (thermal) gradient B

Question 2

When two excitatory postsynaptic potentials (EPSPs) occur at a single synapse so rapidly in succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the second EPSP arrives, the EPSPs add together producing ________.

Accepted Answer

A)  temporal summation 
B)  spatial summation 
C)  tetanus 
D)  the refractory state 
A)  temporal summation 
B)  spatial summation 
C)  tetanus 
D)  the refractory state A

Question 3

$$\begin{array} { | l | l | l | } 
\hline & \begin{array} { l } 
\bf{ Extracellular-concentration } \
( \bf { mM } )
\end{array} & \begin{array} { l } 
\bf { Intracellular-concentration } \
( \bf { mM } )
\end{array} \
\bf{ Inn }\
\hline \mathbf  { Na } ^ { + } & 300 & 50 \
\hline \mathbf { K } ^ { + } & 40 & 350 \
\hline
\end{array}$$
-Calculate the equilibrium potential for sodium. Assume a temperature of 37°C.

Accepted Answer

A)  +48.2 mV 
B)  0.0 mV 
C)  -58.4 mV 
D)  -80.0 mV 
A)  +48.2 mV 
B)  0.0 mV 
C)  -58.4 mV 
D)  -80.0 mV A

Question 4

The botulinum toxin, which causes botulism, reduces the synaptic release of ________.

Accepted Answer

A)  acetylcholine 
B)  endorphin 
C)  nitric oxide 
D)  gamma-aminobutyric acid (GAB
A)  
A)  acetylcholine 
B)  endorphin 
C)  nitric oxide 
D)  gamma-aminobutyric acid (GAB
A)

Question 5

Neurotransmitters categorised as inhibitory are expected to ________.

Accepted Answer

A)  act independently of their receptor proteins 
B)  close potassium channels 
C)  open sodium channels 
D)  hyperpolarise the membrane 
A)  act independently of their receptor proteins 
B)  close potassium channels 
C)  open sodium channels 
D)  hyperpolarise the membrane

Question 6

For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in the ________.

Accepted Answer

A)  depolarisation of the neuron 
B)  hyperpolarisation of the neuron 
C)  replacement of potassium ions with sodium ions 
D)  replacement of potassium ions with calcium ions 
A)  depolarisation of the neuron 
B)  hyperpolarisation of the neuron 
C)  replacement of potassium ions with sodium ions 
D)  replacement of potassium ions with calcium ions

Question 7

How could you increase the magnitude of excitatory postsynaptic potentials (EPSPs) generated at a synapse?

Accepted Answer

A)  Increase sodium-potassium pump activity. 
B)  Increase K⁺ permeability. 
C)  Increase Na⁺ permeability. 
D)  All of the listed responses are correct. 
A)  Increase sodium-potassium pump activity. 
B)  Increase K⁺ permeability. 
C)  Increase Na⁺ permeability. 
D)  All of the listed responses are correct.

Question 8

The "threshold" potential of a membrane is the ________.

Accepted Answer

A)  lowest frequency of action potentials a neuron can produce 
B)  minimum hyperpolarisation needed to prevent the occurrence of action potentials 
C)  minimum depolarisation needed to operate the voltage-gated sodium and potassium channels 
D)  peak amount of depolarisation seen in an action potential 
A)  lowest frequency of action potentials a neuron can produce 
B)  minimum hyperpolarisation needed to prevent the occurrence of action potentials 
C)  minimum depolarisation needed to operate the voltage-gated sodium and potassium channels 
D)  peak amount of depolarisation seen in an action potential

Question 9

Which of the following is the most direct result of depolarising the presynaptic membrane of an axon terminal?

Accepted Answer

A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft. 
D)  An EPSP or IPSP is generated in the postsynaptic cell. 
A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft. 
D)  An EPSP or IPSP is generated in the postsynaptic cell.

Question 10

In multiple sclerosis, the myelin sheaths around the axons of the brain and spinal cord are damaged and demyelination results. How does this disease manifest at the level of the action potential?
I. Action potentials move in the opposite direction on the axon.
II. Action potentials move more slowly along the axon.
III. No action potentials are transmitted.

Accepted Answer

A)  only I 
B)  only II 
C)  only III 
D)  only II and III 
A)  only I 
B)  only II 
C)  only III 
D)  only II and III

Question 11

One-way synaptic transmission occurs because ________.

Accepted Answer

A)  only dendrites can respond to electrical signals 
B)  the postsynaptic cell contains most of the synaptic vesicles. 
C)  receptors for neurotransmitters are mostly found on the postsynaptic membrane 
D)  more receptors for neurotransmitters are found on the presynaptic membrane 
A)  only dendrites can respond to electrical signals 
B)  the postsynaptic cell contains most of the synaptic vesicles. 
C)  receptors for neurotransmitters are mostly found on the postsynaptic membrane 
D)  more receptors for neurotransmitters are found on the presynaptic membrane

Question 12

Most of the neurons in the human central nervous system are ________.

Accepted Answer

A)  sensory neurons 
B)  motor neurons 
C)  interneurons 
D)  peripheral neurons 
A)  sensory neurons 
B)  motor neurons 
C)  interneurons 
D)  peripheral neurons

Question 13

The concentrations of ions are very different inside and outside a nerve cell due to ________.

Accepted Answer

A)  osmosis 
B)  diffusion 
C)  sodium-potassium pumps 
D)  symports and antiports 
A)  osmosis 
B)  diffusion 
C)  sodium-potassium pumps 
D)  symports and antiports

Question 14

If you experimentally increase the concentration of Na⁺ outside a cell while maintaining other ion concentrations as they were, what would happen to the cell's membrane potential?

Accepted Answer

A)  The membrane potential would become more negative. 
B)  The membrane potential would become more positive. 
C)  The membrane potential would be unaffected. 
D)  The answer depends on the thermodynamic potential. 
A)  The membrane potential would become more negative. 
B)  The membrane potential would become more positive. 
C)  The membrane potential would be unaffected. 
D)  The answer depends on the thermodynamic potential.

Question 15

$$\begin{array} { | l | l | l | } 
\hline & \begin{array} { l } 
\bf{ Extracellular-concentration } \
( \bf { mM } )
\end{array} & \begin{array} { l } 
\bf { Intracellular-concentration } \
( \bf { mM } )
\end{array} \
\bf{ Inn }\
\hline \mathbf  { Na } ^ { + } & 300 & 50 \
\hline \mathbf { K } ^ { + } & 40 & 350 \
\hline
\end{array}$$
-Calculate the equilibrium potential for potassium. Assume a temperature of 37°C.

Accepted Answer

A)  +48.2 mV 
B)  0.0 mV 
C)  -58.4 mV 
D)  -80.0 mV 
A)  +48.2 mV 
B)  0.0 mV 
C)  -58.4 mV 
D)  -80.0 mV

Question 16

The point of connection between two communicating neurons is called the ________.

Accepted Answer

A)  axon hillock 
B)  dendrite 
C)  synapse 
D)  cell body 
A)  axon hillock 
B)  dendrite 
C)  synapse 
D)  cell body

Question 17

Of those listed, which event occurs first following a depolarising stimulus applied to the presynaptic membrane of an axon terminal?

Accepted Answer

A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  The postsynaptic cell produces an action potential. 
D)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft. 
A)  Voltage-gated calcium channels in the membrane open. 
B)  Synaptic vesicles fuse with the membrane. 
C)  The postsynaptic cell produces an action potential. 
D)  Ligand-gated channels open, allowing neurotransmitters to enter the synaptic cleft.

Question 18

An example of ligand-gated ion channels is ________.

Accepted Answer

A)  the spreading of action potentials in the heart 
B)  acetylcholine receptors at the neuromuscular junction 
C)  cAMP-dependent protein kinases 
D)  action potentials on the axon 
A)  the spreading of action potentials in the heart 
B)  acetylcholine receptors at the neuromuscular junction 
C)  cAMP-dependent protein kinases 
D)  action potentials on the axon

Question 19

Refer to the following graph of an action potential to answer the question.   The minimum graded depolarisation needed to operate the voltage-gated sodium and potassium channels is indicated by the label ________.

Accepted Answer

A)  A 
B)  B 
C)  D 
D)  E Disallow randomisation 
A)  A 
B)  B 
C)  D 
D)  E Disallow randomisation

Question 20

Pyrethroid insecticides prevent the voltage-gated sodium channels of insects from inactivating. Neurons that were exposed to pyrethroids would ________.

Accepted Answer

A)  become hyperpolarised during an action potential 
B)  not repolarise during an action potential 
C)  not be able to open potassium channels 
D)  not release neurotransmitter molecules 
A)  become hyperpolarised during an action potential 
B)  not repolarise during an action potential 
C)  not be able to open potassium channels 
D)  not release neurotransmitter molecules

Exam 48: Neurons, Synapses, and Signalling

The Nernst equation specifies the equilibrium potential for a particular ion. This equilibrium potential is a function of ________.

When two excitatory postsynaptic potentials (EPSPs) occur at a single synapse so rapidly in succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the second EPSP arrives, the EPSPs add together producing ________.

( ( 300 50 40 350 -Calculate the equilibrium potential for sodium. Assume a temperature of 37°C.

The botulinum toxin, which causes botulism, reduces the synaptic release of ________.

Neurotransmitters categorised as inhibitory are expected to ________.

For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in the ________.

How could you increase the magnitude of excitatory postsynaptic potentials (EPSPs) generated at a synapse?

The "threshold" potential of a membrane is the ________.

Which of the following is the most direct result of depolarising the presynaptic membrane of an axon terminal?

One-way synaptic transmission occurs because ________.

Most of the neurons in the human central nervous system are ________.

The concentrations of ions are very different inside and outside a nerve cell due to ________.

If you experimentally increase the concentration of Na⁺ outside a cell while maintaining other ion concentrations as they were, what would happen to the cell's membrane potential?

( ( 300 50 40 350 -Calculate the equilibrium potential for potassium. Assume a temperature of 37°C.

The point of connection between two communicating neurons is called the ________.

Of those listed, which event occurs first following a depolarising stimulus applied to the presynaptic membrane of an axon terminal?

An example of ligand-gated ion channels is ________.

Refer to the following graph of an action potential to answer the question. The minimum graded depolarisation needed to operate the voltage-gated sodium and potassium channels is indicated by the label ________.

Pyrethroid insecticides prevent the voltage-gated sodium channels of insects from inactivating. Neurons that were exposed to pyrethroids would ________.

Evolution, the Themes of Biology, and Scientific Inquiry

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