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BIOL 212 Quiz (1).
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Exam of 9 pages for the course Bnsf-Maintenance of Way Operating Rules at Bnsf-Maintenance of Way Operating Rules (BIOL 212 Quiz (1).)
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BIOL 212 QuizWhich ion most readily leaks across a neuron's membrane, helping to establish
the resting potential? - CORRECT ANSWER-K+
In resting neurons, the membrane is selectively permeable to K+ through a K+
channel protein. As K+ leaves the cell along its concentration gradient, the inside
of the membrane becomes negatively charged relative to the outside. Will K+
continue to leave the cell indefinitely? - CORRECT ANSWER-No−−as the interior
of the cell becomes more negative, the electrical gradient counteracts the
movement of K+ out of the cell. Eventually, there is no net movement of K+.
The nucleus and most of the organelles in a neuron are located in the _____. -
CORRECT ANSWER-cell body
For a neuron at rest with a membrane potential of -65 mV, an increase in the
movement of potassium ions out of that neuron's cytoplasm would result in the
________. - CORRECT ANSWER-hyperpolarization of the neuron.
The operation of the sodium-potassium "pump" moves ________. - CORRECT
ANSWER-sodium ions out of the cell and potassium ions into the cell.
The membrane potential in which there is no net movement of the ion across the
membrane is called the _____. - CORRECT ANSWER-equilibrium potential
ATP hydrolysis directly powers the movement of ________. - CORRECT
ANSWER-Na+ out of the cell.
Which of the following statements about action potentials is correct? - CORRECT
ANSWER-Action potentials are propagated down the length of the axon.
The three distinct phases of an action potential occur in what order? - CORRECT
ANSWER-depolarization, repolarization, hyperpolarization
The "threshold" potential of a membrane is the _____. - CORRECT
ANSWER-minimum depolarization needed to operate the voltage-gated sodium
and potassium channels
, What would probably happen if a long neuron had one continuous myelin sheath
down the length of the axon with no nodes of Ranvier? - CORRECT
ANSWER-The signal would fade because it is not renewed by the opening of
more sodium channels.
How do myelin sheaths increase the speed with which action potentials are
propagated along an axon? - CORRECT ANSWER-They cause action potentials
to "jump" down the axon rather than travel in a continuous path along every site
on the axon.
What type of ion channel is responsible for the depolarization phase of an action
potential? - CORRECT ANSWER-Voltage gated Na+ channels
In a synapse, neurotransmitter chemicals are received by ________. -
CORRECT ANSWER-The postsynaptic membrane
Excitatory postsynaptic potentials (EPSPs) produced nearly simultaneously by
different synapses on the same postsynaptic neuron can also add together,
creating ________. - CORRECT ANSWER-Summation
The somatic nervous system can alter the activities of its targets, the skeletal
muscle fibers, because ________. - CORRECT ANSWER-Its signals bind to
receptor proteins at synapses on the muscles.
Which of these is the correct direction of information flow in a neuron? -
CORRECT ANSWER-dendrite → cell body → axon
Which of these statements about neuronal action potentials is false? Action
potentials _. - CORRECT ANSWER-Begin with a hyperpolarization phase,
lowering the membrane potential below the resting membrane potential.
The Presynaptic release of neurotransmitter___. - CORRECT ANSWER-requires
electrical synapses.
The Postsynaptic cells____. - CORRECT ANSWER-are always connected to
presynaptic cells by electrical synapses.
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