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Test Bank for Becker's World of the Cell: Ch 22, 23 (10th Edition by Jeff Hardin)
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Test Bank for Becker's World of the Cell: Ch 22, 23 (10th Edition by Jeff Hardin)
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Test Bank for Becker's World of theCell: Ch 22, 23 (10th Edition by Jeff
Hardin)
1) How many neuronal connections are there in the human brain?
A) millions
B) 1 billion
C) 10 billion
D) 100 billion
E) trillions - ANSe) trillions
2) Each of the following is a type of glial cells except
A) interneurons.
B) oligodendrocytes.
C) astrocytes.
D) Schwann cells.
E) microglia cells. - ANSA) interneurons.
3) The axon branches of a typical neuron terminate at structures called
A) synapses.
B) boutons.
C) glia.
D) nodes of Ranvier.
E) the myelin sheath. - ANSboutons
4) The resting potential of a particular nerve cell is −66 mV. Depolarization of the neuron
membrane will shift the membrane potential to
A) −90 mV.
B) −75 mV.
C) 0 mV.
D) +45 mV.
E) +66 mV. - ANSD) +45 mV.
5) Plasma membrane permeability of which of the following ions is most important in generating
the resting membrane potential?
A) sodium ions
B) potassium ions
C) chloride ions
D) calcium ions
,E) None of the above generates resting membrane potential. - ANSB) potassium ions
Using the patch clamp technique, a researcher measures a single channel in a membrane with
a potential of −60 mV. The receptor channel passes 3 pA (picoamperes; 1 pA = 10−12 ampere)
of ionic current over a period of 8 msec that it remains open.
6) An electrical current of 1 A is approximately 6 × 1018 electrical charges per second; how
many monovalent ions pass through the channel when it is open?
A) 144,000 ions
B) 18,000 ions
C) 8,640,000 ions
D) 8640 ions
E) Cannot be calculated from the information given. - ANSA) 144,000 ions
Using the patch clamp technique, a researcher measures a single channel in a membrane with
a potential of −60 mV. The receptor channel passes 3 pA (picoamperes; 1 pA = 10−12 ampere)
of ionic current over a period of 8 msec that it remains open.
7) If the resting potential was changed to −66 mV, the next time the channel opened for 8 msec,
how many monovalent ions would pass through the channel?
A) 144,000 ions
B) 130,000.
C) 158,000
D) 18,000
E) There is insufficient information to calculate the number of ions. - ANSA) 144,000 ions
8) At which point in the graph do voltage-gated potassium channels open?
A) A
B) B
C) C
D) D
E) E - ANSc
9) Based on the graph, the threshold voltage appears to be approximately
A) +60 mV.
B) +30 mV.
C) 0 mV.
D) −30 mV.
E) −60 mV - ANSE) −60 mV.
, 10) Based on the graph, how soon could another action potential be easily initiated (at the end
of the relative refractory period) after the first stimulus?
A) less than 0.5 msec
B) 1 msec
C) 2 msec
D) 3 msec
E) 4 msec - ANSD) 3 msec
11) Which point on the graph represents the threshold potential?
A) A
B) B
C) C
D) D
E) E - ANSb
12) If myelin was lost from the neuron firing the action potential graphed, the action potential
cycle would
A) go much faster than depicted in the graph.
B) go much faster than normal but not peak at 30 mV.
C) go slower than depicted in the graph.
D) go much slower than normal but peak much higher than 30 mV.
E) remain the same. - ANSE) remain the same.
13) The parts of the graph indicated between points C and E represent
A) depolarization.
B) hyperpolarization.
C) the absolute refractory period.
D) repolarization.
E) sodium channel activity. - ANSD) repolarization.
14) If the membrane represented in the graph was stimulated in the presence of a drug that
specifically inhibits sodium channels, the membrane would
A) not depolarize.
B) depolarize for one stimulus but not for a second stimulus.
C) depolarize but not repolarize.
D) repolarize only to the threshold potential.
E) become permanently hyperpolarized. - ANSA) not depolarize.
15) Each of the following contributes to the unidirectional propagation of nerve signals except
A) dendrites only receive signals.
B) presynaptic neurotransmitter secretion is separated from postsynaptic receptors.
C) neuron membranes have a refractory period following generation of an action potential.
D) ion channels are oriented to transport ions only into the neuron.
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