Question 1

A graded hyperpolarization of a membrane can be induced by

Accepted Answer

A) increasing its membrane's permeability to Na⁺. 
B) decreasing its membrane's permeability to H⁺. 
C) decreasing its membrane's permeability to Cl⁻. 
D) increasing its membrane's permeability to Ca⁺⁺. 
E) increasing its membrane's permeability to K⁺. 
A) increasing its membrane's permeability to Na⁺. 
B) decreasing its membrane's permeability to H⁺. 
C) decreasing its membrane's permeability to Cl⁻. 
D) increasing its membrane's permeability to Ca⁺⁺. 
E) increasing its membrane's permeability to K⁺.

Question 2

Temporal summation always involves

Accepted Answer

A) both inhibitory and excitatory inputs. 
B) synapses at more than one site. 
C) inputs that are not simultaneous. 
D) electrical synapses. 
E) multiple inputs at a single synapse. 
A) both inhibitory and excitatory inputs. 
B) synapses at more than one site. 
C) inputs that are not simultaneous. 
D) electrical synapses. 
E) multiple inputs at a single synapse.

Question 3

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

Accepted Answer

A) the depolarization of the neuron. 
B) the hyperpolarization of the neuron. 
C) the replacement of potassium ions with sodium ions. 
D) the replacement of potassium ions with calcium ions. 
E) the neuron switching on its sodium-potassium pump to restore the initial conditions. 
A) the depolarization of the neuron. 
B) the hyperpolarization of the neuron. 
C) the replacement of potassium ions with sodium ions. 
D) the replacement of potassium ions with calcium ions. 
E) the neuron switching on its sodium-potassium pump to restore the initial conditions.

Question 4

Self-propagation and refractory periods are typical of

Accepted Answer

A) action potentials. 
B) graded hyperpolarizations. 
C) excitatory postsynaptic potentials. 
D) threshold potentials. 
E) resting potentials. 
A) action potentials. 
B) graded hyperpolarizations. 
C) excitatory postsynaptic potentials. 
D) threshold potentials. 
E) resting potentials.

Question 5

Neurotransmitters categorized as inhibitory are expected to

Accepted Answer

A) act independently of their receptor proteins. 
B) close potassium channels. 
C) open sodium channels. 
D) close chloride channels. 
E) hyperpolarize the membrane. 
A) act independently of their receptor proteins. 
B) close potassium channels. 
C) open sodium channels. 
D) close chloride channels. 
E) hyperpolarize the membrane.

Question 6

Immediately after an action potential passes along an axon,it is not possible to generate a second action potential; thus,we state that the membrane is briefly

Accepted Answer

A) hyperexcitable. 
B) refractory. 
C) fully depolarized. 
D) above threshold. 
E) at the equilibrium potential. 
A) hyperexcitable. 
B) refractory. 
C) fully depolarized. 
D) above threshold. 
E) at the equilibrium potential.

Question 7

For the following questions,refer to the graph of an action potential.
  
-The neuronal membrane is at its resting potential at label

Accepted Answer

A) 
A)  
B) 
B)  
C) 
C)  
D) 
D)  
E) 
E)  
A) 
A)  
B) 
B)  
C) 
C)  
D) 
D)  
E) 
E)

Question 8

The major excitatory neurotransmitter of the human brain is

Accepted Answer

A) acetylcholine. 
B) epinephrine. 
C) glutamate. 
D) nitric oxide. 
E) GABA. 
A) acetylcholine. 
B) epinephrine. 
C) glutamate. 
D) nitric oxide. 
E) GABA.

Question 9

A neuropeptide that might function as a natural analgesic is

Accepted Answer

A) acetylcholine. 
B) epinephrine. 
C) endorphin. 
D) nitric oxide. 
E) GABA. 
A) acetylcholine. 
B) epinephrine. 
C) endorphin. 
D) nitric oxide. 
E) GABA.

Question 10

In response to a stimulus,Na⁺ and K⁺ channels open,allowing for depolarization.The channels respond independently,with

Accepted Answer

A) both Na⁺ and K⁺ channels opening simultaneously and both remaining active until the end of the action potential. 
B) the K⁺ channel opening first, then the Na⁺ channel opening, and only the Na⁺ channel remaining active until the end of the action potential. 
C) the Na⁺ channel opening first, then K⁺ channel opening and only the K⁺ channel remaining active until the end of the action potential. 
D) both Na⁺ and K⁺ channels opening simultaneously, with the K⁺ channel closing before the Na⁺ channel. 
E) the Na⁺ channel opening first, then the K⁺ channel opening, and both remaining active until the end of the action potential. 
A) both Na⁺ and K⁺ channels opening simultaneously and both remaining active until the end of the action potential. 
B) the K⁺ channel opening first, then the Na⁺ channel opening, and only the Na⁺ channel remaining active until the end of the action potential. 
C) the Na⁺ channel opening first, then K⁺ channel opening and only the K⁺ channel remaining active until the end of the action potential. 
D) both Na⁺ and K⁺ channels opening simultaneously, with the K⁺ channel closing before the Na⁺ channel. 
E) the Na⁺ channel opening first, then the K⁺ channel opening, and both remaining active until the end of the action potential.

Question 11

Why do Na⁺ ions enter the cell when voltage-gated Na⁺ channels are opened in neurons?

Accepted Answer

A) because the Na⁺ concentration is much lower outside the cell than it is inside 
B) because the Na⁺ ions are actively transported by the sodium-potassium pump into the cell 
C) because the Na⁺ concentration is much higher outside the cell than it is inside, and the Na⁺ ions are attracted to the negatively charged interior 
D) because the Na⁺ concentration is much higher outside the cell than it is inside, and the Na⁺ ions are actively transported by the sodium-potassium pump into the cell 
E) because the Na⁺ ions are then able to pass through the plasma membrane unassisted 
A) because the Na⁺ concentration is much lower outside the cell than it is inside 
B) because the Na⁺ ions are actively transported by the sodium-potassium pump into the cell 
C) because the Na⁺ concentration is much higher outside the cell than it is inside, and the Na⁺ ions are attracted to the negatively charged interior 
D) because the Na⁺ concentration is much higher outside the cell than it is inside, and the Na⁺ ions are actively transported by the sodium-potassium pump into the cell 
E) because the Na⁺ ions are then able to pass through the plasma membrane unassisted

Question 12

In a simple synapse,neurotransmitter chemicals are released by

Accepted Answer

A) the dendritic membrane. 
B) the presynaptic membrane. 
C) axon hillocks. 
D) cell bodies. 
E) ducts on the smooth endoplasmic reticulum. 
A) the dendritic membrane. 
B) the presynaptic membrane. 
C) axon hillocks. 
D) cell bodies. 
E) ducts on the smooth endoplasmic reticulum.

Question 13

The fastest possible conduction velocity of action potentials is observed in

Accepted Answer

A) thin, non-myelinated neurons. 
B) thin, myelinated neurons. 
C) thick, non-myelinated neurons. 
D) thick, myelinated neurons. 
A) thin, non-myelinated neurons. 
B) thin, myelinated neurons. 
C) thick, non-myelinated neurons. 
D) thick, myelinated neurons.

Question 14

Adjacent neurons with direct (non-neurotransmitter)action potential transfer are said to have electrical synapses,based on the presence of

Accepted Answer

A) tight junctions at their point of contact. 
B) gap junctions at their point of contact. 
C) leaky junctions at their point of contact. 
D) anchoring junctions at their point of contact. 
E) desmosomes at their point of contact. 
A) tight junctions at their point of contact. 
B) gap junctions at their point of contact. 
C) leaky junctions at their point of contact. 
D) anchoring junctions at their point of contact. 
E) desmosomes at their point of contact.

Question 15

When several EPSPs arrive at the axon hillock from different presynaptic locations,depolarizing the postsynaptic cell to threshold for an action potential,this is an example of

Accepted Answer

A) temporal summation. 
B) spatial summation. 
C) tetanus. 
D) the refractory state. 
E) an action potential with an abnormally high peak of depolarization. 
A) temporal summation. 
B) spatial summation. 
C) tetanus. 
D) the refractory state. 
E) an action potential with an abnormally high peak of depolarization.

Question 16

A "resting" motor neuron is expected to

Accepted Answer

A) release lots of acetylcholine. 
B) have high permeability to sodium ions. 
C) be equally permeable to sodium and potassium ions. 
D) exhibit a resting potential that is more negative than the "threshold" potential. 
E) have a higher concentration of sodium ions on the inside of the cell than on the outside. 
A) release lots of acetylcholine. 
B) have high permeability to sodium ions. 
C) be equally permeable to sodium and potassium ions. 
D) exhibit a resting potential that is more negative than the "threshold" potential. 
E) have a higher concentration of sodium ions on the inside of the cell than on the outside.

Question 17

The botulinum toxin reduces the synaptic release of

Accepted Answer

A) acetylcholine. 
B) epinephrine. 
C) endorphin. 
D) nitric oxide. 
E) GABA. 
A) acetylcholine. 
B) epinephrine. 
C) endorphin. 
D) nitric oxide. 
E) GABA.

Question 18

When several IPSPs arrive at the axon hillock rapidly in sequence from a single presynaptic location,hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential,this is an example of

Accepted Answer

A) temporal summation. 
B) spatial summation. 
C) tetanus. 
D) the refractory state. 
E) an action potential with an abnormally high peak of depolarization. 
A) temporal summation. 
B) spatial summation. 
C) tetanus. 
D) the refractory state. 
E) an action potential with an abnormally high peak of depolarization.

Question 19

A neurophysiologist is investigating nerve reflexes in two different animals: a crab and a fish.Action potentials are found to pass more rapidly along the fish's neurons.What is the most likely explanation?

Accepted Answer

A) The fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do. 
B) Unlike the crab, the fish's axons are wrapped in myelin. 
C) There are more ion channels in the axons of the crab compared with fish axons. 
D) Unlike the crab, the fish's axons are wrapped in myelin, and the fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do. 
E) The crab lives in salt water and the fish lives in freshwater. 
A) The fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do. 
B) Unlike the crab, the fish's axons are wrapped in myelin. 
C) There are more ion channels in the axons of the crab compared with fish axons. 
D) Unlike the crab, the fish's axons are wrapped in myelin, and the fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do. 
E) The crab lives in salt water and the fish lives in freshwater.

Question 20

For the following questions,refer to the graph of an action potential.
  
-The cell is not hyperpolarized; however,repolarization is in progress,as the sodium channels are closing or closed,and many potassium channels have opened at label

Accepted Answer

A) 
A)  
B) 
B)  
C) 
C)  
D) 
D)  
E) 
E)  
A) 
A)  
B) 
B)  
C) 
C)  
D) 
D)  
E) 
E)

Exam 48: Neurons,Synapses,and Signalling

A graded hyperpolarization of a membrane can be induced by

Temporal summation always involves

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

Self-propagation and refractory periods are typical of

Neurotransmitters categorized as inhibitory are expected to

Immediately after an action potential passes along an axon,it is not possible to generate a second action potential; thus,we state that the membrane is briefly

For the following questions,refer to the graph of an action potential. -The neuronal membrane is at its resting potential at label

The major excitatory neurotransmitter of the human brain is

A neuropeptide that might function as a natural analgesic is

In response to a stimulus,Na⁺ and K⁺ channels open,allowing for depolarization.The channels respond independently,with

Why do Na⁺ ions enter the cell when voltage-gated Na⁺ channels are opened in neurons?

In a simple synapse,neurotransmitter chemicals are released by

The fastest possible conduction velocity of action potentials is observed in

Adjacent neurons with direct (non-neurotransmitter)action potential transfer are said to have electrical synapses,based on the presence of

When several EPSPs arrive at the axon hillock from different presynaptic locations,depolarizing the postsynaptic cell to threshold for an action potential,this is an example of

A "resting" motor neuron is expected to

The botulinum toxin reduces the synaptic release of

When several IPSPs arrive at the axon hillock rapidly in sequence from a single presynaptic location,hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential,this is an example of

A neurophysiologist is investigating nerve reflexes in two different animals: a crab and a fish.Action potentials are found to pass more rapidly along the fish's neurons.What is the most likely explanation?

For the following questions,refer to the graph of an action potential. -The cell is not hyperpolarized; however,repolarization is in progress,as the sodium channels are closing or closed,and many potassium channels have opened at label

Introduction: Evolution and Themes of Biology

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure,Growth,and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Nervous Systems

Sensory and Motor Mechanisms

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

Filters