AP Bio Chapter 34
C
A biologist exposes mice to mutagenizing X rays to generate an array of different mutants. He hopes to generate a mutant form of acetylcholinesterase that will be functional at normal body temperature but inactive at a higher temperature. Which step below would work as an initial screening step in the biologist's quest to eventually identify a mutant of this type? A. Look for mice that develop hyperactivity and rapid muscle movements as their body temperature changes from normal to the higher temperature of an induced fever. B. Look for mice with normal muscle contraction-relaxation activity at normal body temperature that develop an inability to contract muscles during an induced fever. C. Look for mice with normal muscle contraction-relaxation activity at normal body temperature that develop continuous muscle contraction during an induced fever. D. Look for mice with a normal response to loud noise that become more easily startled by the same noise stimulus as their body temperature rises during an induced fever.
D
A biologist tests four different compounds for their effects on various stages of synaptic transmission by a neuron. In her tests, the biologist observes the neuron's ability to carry out certain functions in response to electrical stimulation of the neuron. The table above summarizes her results. A checkmark indicates normal function. Based on these results, which compound would be classified as a sodium channel blocker and which would be classified as a voltage-gated calcium channel blocker? A. 4 = voltage-gated sodium channel blocker; 1 = voltage-gated calcium channel blocker B. 1 = voltage-gated sodium channel blocker; 2 = voltage-gated calcium channel blocker C. 2 = voltage-gated sodium channel blocker; 3 = voltage-gated calcium channel blocker D. 2 = voltage-gated sodium channel blocker; 4 = voltage-gated calcium channel blocker
C
A molecule of rhodopsin that absorbs light leads to a chain of events that A. opens Na+ channels. B. activates translation. C. activates a G protein-mediated cascade. D. responds to the exact same wavelength as other molecules of rhodopsin. E. depolarizes the cell membrane.
A
A nerve is a A. bundle of axons carrying information to and from the central nervous system. B. bundle of axons carrying information from the central nervous system to the peripheral nervous system only. C. single dendrite carrying information about motor and sensory stimuli simultaneously. D. bundle of dendrites that carries information about motor and sensory stimuli simultaneously. E. single axon carrying information to and from the central nervous system.
C
A person with a spinal cord injury cannot voluntarily move their leg, yet a physician can elicit a jerking movement of the leg by gently tapping on the person's knee. How can this be explained? A. As a result of the injury, information is blocked from moving from the brain to the leg, but information can move from the leg to the brain. B. The neural pathway involved in the leg movement does not pass through the spinal cord. C. The part of the spinal cord involved in the neural circuitry that enables the leg to move is intact even though another region of the spinal cord is damaged. D. The movement of leg muscles following tapping with a hammer does not result from neural stimulation.
A
A student creates a study guide describing each of the five phases of a neuronal action potential. How should she fill in the blanks for the phase indicated above? A. A = Rapid diffusion into cell; B = Equal movement in and out of cell; C = Most positive value B. A = Slow diffusion out of cell; B = No movement; C = Most positive value C. A = Equal movement in and out of cell; B = No movement; C = Most negative value D. A = Rapid diffusion out of cell; B = Equal movement in and out of cell; C = Most negative value
C
A student draws the diagram above to show a distribution of positive and negative ions on both sides of a cell membrane. The student states that the membrane potential across this membrane is 0 mV. He then states that this membrane can only develop a negative membrane potential if the negatively charged ions migrate across the membrane. Evaluate the accuracy of the two statements. A. The second statement is accurate but the first statement is not. B. Both statements are accurate. C. The first statement is accurate but the second statement is not. D. Neither statement is accurate.
C
Action potentials travel very fast in _______ axons. A. unmyelinated B. small-diameter C. myelinated D. longer E. shorter
A
After a stimulus results in initial depolarization of a region of cell membrane of a neuron, a threshold voltage is reached. Once this happens, which of the following takes place? A. A large number of voltage-gated sodium channels quickly open, causing a rapid change in membrane potential. B. Voltage-gated sodium and potassium channels quickly close, and recovery begins. C. Voltage-gated sodium channels quickly close, voltage-gated potassium channels open, and recovery begins. D. A large number of voltage-gated potassium channels quickly open, causing a rapid change in membrane potential.
C
An electrode is inserted into the axon of a neuron and a second electrode is placed in the extracellular fluid surrounding the neuron. A voltmeter connected to the electrodes displays the electrical potential across the axon membrane. A biologist records the voltage displayed on the voltmeter at one-minute intervals for 7 minutes. What movement of ions across the axon membrane occurred in this system between the 1-minute reading and the 6-minute reading? A. K+ ions moved out of the axon and an equal number of Na+ ions moved back into the axon. B. Na+ ions moved out of the axon and an equal number of Na+ ions moved back into the axon. C. K+ ions moved out of the axon and an equal number of K+ ions moved back into the axon. D. No ions moved in either direction across the axon membrane.
A
An odorant molecule receptor is an example of a(n) A. chemoreceptor. B. electroreceptor. C. mechanoreceptor. D. photoreceptor. E. stretch receptor.
A
Arrange the numbered events listed in the table in order of their occurrence during a chemical synaptic transmission. A. 5, 1, 4, 2, 3 B. 5, 4, 1, 2, 3 C. 4, 1, 3, 2, 5 D. 1, 4, 5, 3, 2
B
At the peak of the action potential, A. voltage-gated sodium channels open and voltage-gated potassium channels close. B. voltage-gated sodium channels close and voltage-gated potassium channels open. C. all voltage-gated channels open. D. all voltage-gated channels close.
D
During the course of an action potential, the membrane potential rapidly spikes and then falls. What causes the fall? A. Na+ leak channels close. B. Voltage-gated K+ channels close. C. The voltage-gated Na+ channels enter a refractory period. D. Voltage-gated Na+ channels close and voltage-gated K+ channels open. E. K+ leak channels close, causing depolarization.
D
If a brain tumor were pressing against your amygdala, causing it to be activated continuously, you would most likely feel A. angry. B. hungry. C. depressed. D. fearful. E. joyful.
C
Interneurons A. determine whether a particular motor neuron is excited or inhibited. B. connect a sensory neuron and motor neuron. C. Both a and b D. are located throughout the body.
E
Ionotropic receptors are _______; metabotropic receptors are _______. A. a type of metabotropic receptor; only in electrical synapses B. ion channels; ion channels C. only in electrical synapses; G protein-linked receptors D. G protein-linked receptors; ion channels E. ion channels; G protein-linked receptors
B
Motor neurons send their axons out through the _______ of the spinal cord to innervate muscles. A. ventral horn B. ventral root C. dorsal root D. lateral horn E. dorsal horn
E
Neurons generally receive information via their A. axons. B. nerves. C. glial cells. D. cell bodies. E. dendrites and cell bodies.
A
Review the information listed in the summary table for an action potential in a neuron. Indicate any information listed that is not accurate as written. A. The phase names for 2 and 3 should be reversed. B. The voltage drop during phase 4 does not drop below the voltage for resting potential. C. All information is accurate. D. The positive and negative signs on all voltage readings should be reversed.
B
Sensory axons enter the spinal cord through the A. pons. B. dorsal roots. C. sympathetic ganglia. D. ventral roots.
D
Synapses between a neuron and another cell can be all of the following except A. joined by gap junctions. B. chemical. C. excitatory. D. controlled by glial cells. E. inhibitory.
D
Tetrodotoxin (TTX) is a neurotoxin that blocks voltage-gated Na+ channels. What will happen in an organism that ingests TTX? A. In sufficient quantities, it will be fatal in the organism. B. Neurotransmitter release will be impaired. C. Action potentials will be impaired. D. All of the above
C
The autonomic nervous system (ANS) does not A. control effectors other than the skeletal muscles. B. control involuntary physiological functions. C. control sensors of smooth muscle. D. contain the parasympathetic nervous system. E. contain the sympathetic nervous system.
A
The central nervous system A. is made up of relatively large structures composed mainly of integrating neurons and associated glial cells. B. can be separated into the sympathetic and parasympathetic divisions. C. reaches every tissue of the body. D. is a bundle of axons carrying information to and from the peripheral nervous system. E. is composed of the cranial and spinal nerves.
D
The depolarization of the presynaptic membrane of an axon terminal at a neuromuscular junction most directly causes A. neurotransmitter to bind to receptors on the postsynaptic membrane. B. an action potential in the postsynaptic cell. C. synaptic vesicles to fuse with the membrane. D. voltage-gated Ca2+ channels in the membrane to open. E. the opening of chemically sensitive gates that allow neurotransmitter to spill into the synaptic cleft.
A
The graph shows the action potential produced in the axon of a neuron before (dotted purple line) and after (solid red line) the neuron was exposed to a chemical agent. Based on the change in the action potential trace, how might the chemical agent have affected the neuron? A. The agent blocked voltage-gated potassium channels. B. The agent blocked voltage-gated sodium channels. C. The agent blocked voltage-gated calcium channels. D. The agent blocked voltage-gated potassium and sodium channels.
B
The graph shows the action potential produced in the axon of a neuron before (dotted purple line) and after (solid red line) the neuron was exposed to a chemical agent. Based on the change in the action potential trace, what was the most direct effect that the chemical agent had on the neuron? A. The agent blocked neurotransmitter vesicle formation. B. The agent blocked voltage-gated sodium channels. C. The agent blocked neurotransmitter release from the neuron. D. The agent blocked voltage-gated potassium channels.
C
The organ of Corti is found within the mammalian inner ear and A. transduces electron waves into action potentials. B. is in the vestibular canal. C. contains hair cells with stereocilia. D. sits atop Reissner's membrane. E. is in the tympanic canal.
C
The resting membrane potential is created by A. proton pumps. B. osmosis. C. ion leak channels. D. amino acids. E. calcium.
B
The sodium-potassium pump A. maintains a positive charge difference across the plasma membrane. B. concentrates potassium ions on the inside of the neuron and sodium ions on the outside of the neuron. C. perturbs the resting potential by allowing ion channels to open. D. concentrates sodium ions on the inside of the neuron and potassium ions on the outside of the neuron. E. allows potassium to diffuse out of the neuron.
A
The spinal cord A. communicates information between the brain and the rest of the body. B. is found in all organisms. C. cannot issue commands to the body without input from the brain. D. does not process or integrate much information. E. has a central area of white matter surrounded by gray matter.
B
What must be present at the postsynaptic site within a chemical synapse for the signal to be transmitted? A. Postsynaptic vesicles containing sodium ions B. Membrane receptors that bind neurotransmitter molecules C. Membrane receptors that bind calcium ions D. Postsynaptic vesicles containing neurotransmitter molecules
A
When a neuron is at rest, its sodium channels A. are closed and its potassium channels are open. B. and potassium channels are both closed. C. are open and its potassium channels are closed. D. and potassium channels are both open.
A
Which of the following determines when an individual neuron will fire an action potential? A. When the sum of all the inputs reaches threshold B. Resting membrane potential C. Excitatory stimulation D. When it receives at least 1,000 synaptic inputs E. Inhibitory inputs
D
Which of the following is a pathway that could be found in a reflex arc? A. Sensory neuron, interneuron, brain, motor neuron, muscle B. Sensory neuron, interneuron, muscle, motor neuron C. Sensory neuron, motor neuron, interneuron, muscle D. Sensory neuron, interneuron, motor neuron, muscle
D
Which of the following occurs when a stimulus depolarizes a neuron's membrane to a membrane potential below the voltage threshold? A. Na+ diffuses out of the cell. B. The membrane potential changes from the resting potential to a more negative membrane potential. C. The action potential stops spreading to the next dendrite. D. The inside of the cell becomes less negative in charge relative to the outside of the cell. E. The action potential approaches zero.
C
Which of the following statements about a chemical synapse is true? A. Its presynaptic component undergoes chemical breakdown in response to a signal, and the breakdown product carries the signal to the postsynaptic component. B. Calcium ions relay the signal generated by an action potential in one neuron across the gap to a second neuron. C. Signal transmission occurs by diffusion of a compound called a neurotransmitter through the intercellular space between neurons. D. It allows signal transmission from one neuron to another through a wave of electrochemical change.
B
Which of the following statements describes the forces that operate to establish a resting membrane potential? A. Electrical forces tend to pull K+ ions out of the neuron, and diffusional forces tend to push K+ ions back into the neuron. B. Diffusional forces tend to push K+ ions out of the neuron, and electrical forces tend to pull K+ ions back into the neuron. C. Electrical forces tend to pull K+ ions out of the neuron, and pumping forces tend to push K+ ions back into the neuron. D. Pumping forces tend to push K+ ions out of the neuron, and diffusional forces tend to push K+ ions back into the neuron.
D
Your physician uses a hammer to tap the tendon in your knee, and your lower leg kicks forward. Which of the following represents the pathway of this reflex? A. Interneuron, motor neuron, muscle, sensory neuron, spinal cord B. Interneuron, motor neuron, spinal cord, muscle, sensory neuron C. Sensory neuron, interneuron, motor neuron, muscle, spinal cord D. Sensory neuron, spinal cord, interneuron, motor neuron, muscle E. Interneuron, motor neuron, sensory neuron, spinal cord, muscle
