chapter 37, 38, 39

Assume that a single IPSP has a negative magnitude of —0.5 mV at the axon hillock, and that a single EPSP has a positive magnitude of +0.5 mV. For a neuron with an initial membrane potential of —70 mV, the net effect of the simultaneous arrival of six IPSPs and two EPSPs would be to move the membrane potential to A) -72 mV. B) -71 mV. C) -70 mV. D) -69 mV. E) -68 mV.

A) -72 mV.

The minimum graded depolarization needed to operate the voltage-gated sodium and potassium channels is indicated by the label A) A. B) B. C) C. D) D. E) E.

A) A.

A type of learning that can occur only during a brief period of early life and results in a behavior that is difficult to modify through later experiences is called A) insight. B) imprinting. C) habituation. D) operant conditioning. E) trial-and-error learning.

B) imprinting.

Exercise and emergency reactions include A) increased activity in all parts of the peripheral nervous system. B) increased activity in the sympathetic division and decreased activity in the parasympathetic division. C) decreased activity in the sympathetic division and increased activity in the parasympathetic division. D) increased activity in the enteric nervous system. E) reduced heart rate and blood pressure.

B) increased activity in the sympathetic division and decreased activity in the parasympathetic division.

Assume that excessive consumption of ethanol increases the influx of negative chloride ions into "commonsense" neurons whose action potentials are needed for you to act appropriately and not harm yourself or others. Thus, any resulting poor decisions associated with ethanol ingestion are likely due to A) increased membrane depolarization of "commonsense" neurons. B) increased membrane hyperpolarization of "commonsense" neurons. C) more action potentials in your "commonsense" neurons. D) more EPSPs in your "commonsense" neurons. E) fewer IPSPs in your "commonsense" neurons.

B) increased membrane hyperpolarization of "commonsense" neurons.

The somatic nervous system can alter the activities of its targets, the skeletal muscle fibers, because A) it is electrically coupled by gap junctions to the muscles. B) its signals bind to receptor proteins on the muscles. C) its signals reach the muscles via the blood. D) its light pulses activate contraction in the muscles. E) it is connected to the internal neural network of the muscles.

B) its signals bind to receptor proteins on the muscles.

Muscle cells are stimulated by neurotransmitters released from the synaptic terminals of A) T tubules. B) motor neuron axons. C) sensory neuron axons. D) motor neuron dendrites. E) sensory neuron dendrites.

B) motor neuron axons.

The 11 pairs of appendages projecting from the rostral area of star-nosed moles are A) chemosensory structures. B) tactile structures. C) olfactory structures. D) highly sensitive photoreceptors. E) gustatory structures.

B) tactile structures.

Research has shown that nocturnal animals navigate using A) olfactory cues. B) the North Star. C) the moon. D) landmarks. E) gravity.

B) the North Star.

After the depolarization phase of an action potential, the resting potential is restored by A) the opening of sodium activation gates. B) the opening of voltage-gated potassium channels and the closing of sodium channels. C) a decrease in the membrane's permeability to potassium and chloride ions. D) a brief inhibition of the sodium-potassium pump. E) the opening of more voltage-gated sodium channels.

B) the opening of voltage-gated potassium channels and the closing of sodium channels.

In a simple synapse, neurotransmitter chemicals are released by A) the dendritic membrane. B) the presynaptic membrane. C) axon hillocks. D) cell bodies. E) ducts on the smooth endoplasmic reticulum.

B) the presynaptic membrane.

Motor neurons alter skeletal muscle activities by releasing neurotransmitter because A) they are electrically coupled by gap junctions to the muscles. B) their signals bind to receptor proteins on the muscles. C) their signals reach the muscles via the blood. D) their light pulses activate contraction in the muscles. E) they are connected to the internal neural network of the muscles.

B) their signals bind to receptor proteins on the muscles.

What type of signal is fast and requires daylight with no obstructions? A) olfactory B) visual C) auditory D) tactile E) electrical

B) visual

The following steps refer to various stages in transmission at a chemical synapse. 1. Neurotransmitter binds with receptors associated with the postsynaptic membrane. 2. Calcium ions rush into the neuron's cytoplasm. 3. An action potential depolarizes the membrane of the axon terminal. 4. The ligand-gated ion channels open. 5. The synaptic vesicles release neurotransmitter into the synaptic cleft. Which sequence of events is correct? A) 1 → 2 → 3 → 4 → 5 B) 2 → 3 → 5 → 4 → 1 C) 3 → 2 → 5 → 1 → 4 D) 4 → 3 → 1 → 2 → 5 E) 5 → 1 → 2 → 4 → 3

C) 3 → 2 → 5 → 1 → 4

Which of the following examples describes a behavioral pattern that results from a proximate cause? A) A cat kills a mouse to obtain nutrition. B) A male sheep fights with another male because it helps to improve its social position. C) A female bird lays its eggs because the amount of daylight is decreasing slightly each day. D) A goose squats and freezes motionless to escape a predator. E) A cockroach runs into a crack in the wall and avoids being stepped on.

C) A female bird lays its eggs because the amount of daylight is decreasing slightly each day.

Although many chimpanzees live in environments containing oil palm nuts, members of only a few populations use stones to crack open the nuts. The likely explanation is that A) the behavioral difference is caused by genetic differences between populations. B) members of different populations have different nutritional requirements. C) the cultural tradition of using stones to crack nuts has arisen in only some populations. D) members of different populations differ in learning ability. E) members of different populations differ in manual dexterity.

C) the cultural tradition of using stones to crack nuts has arisen in only some populations.

Where are neurotransmitter receptors located? A) the nuclear membrane B) the nodes of Ranvier C) the postsynaptic membrane D) synaptic vesicle membranes E) the myelin sheath

C) the postsynaptic membrane

Stimuli alter the activity of excitable sensory cells via A) integration. B) transmission. C) transduction. D) transcription. E) amplification.

C) transduction.

A mother goat can recognize its own kid by smell. A) A B) B C) C D) D E) E

D) D

Myosin filaments without actin overlap are in which section of Figure 39.1? A) A B) B C) C D) D E) E

D) D

The membrane potential is closest to the equilibrium potential for potassium at label A) A. B) B. C) C. D) D. E) E.

D) D.

Which of the following is true of innate behaviors? A) Their expression is only weakly influenced by genes. B) They occur with or without environmental stimuli. C) They are limited to invertebrate animals. D) They are expressed in most individuals in a population. E) They occur in invertebrates and some vertebrates but not mammals.

D) They are expressed in most individuals in a population.

Most of the synapses in vertebrates conduct information in only one direction A) as a result of the nodes of Ranvier. B) as a result of voltage-gated sodium channels found only in the vertebrate system. C) because vertebrate nerve cells have dendrites. D) because only the postsynaptic cells can bind and respond to neurotransmitters. E) because the sodium-potassium pump moves ions in one direction.

D) because only the postsynaptic cells can bind and respond to neurotransmitters.

The olfactory bulbs are located in the A) nasal cavity. B) anterior pituitary gland. C) posterior pituitary gland. D) brain. E) brainstem.

D) brain.

The nucleus and most of the organelles in a neuron are located in the A) dendritic region. B) axon hillock. C) axon. D) cell body. E) axon terminals.

D) cell body.

Food and water appetites are under the regulatory influence of the A) cerebrum. B) cerebellum. C) thalamus. D) hypothalamus. E) medulla oblongata.

D) hypothalamus.

The regulation of body temperature derives from the activity of the A) cerebrum. B) cerebellum. C) thalamus. D) hypothalamus. E) medulla oblongata.

D) hypothalamus.

A skeletal muscle with abnormally low levels of calcium ions would be impaired in A) ATP hydrolysis. B) the initiation of an action potential. C) maintaining its resting membrane potential. D) initiating contraction. E) its ability to sustain glycolysis.

D) initiating contraction.

The "threshold" potential of a membrane is the A) point of separation from a living to a dead neuron. B) lowest frequency of action potentials a neuron can produce. C) minimum hyperpolarization needed to prevent the occurrence of action potentials. D) minimum depolarization needed to operate the voltage-gated sodium and potassium channels. E) peak amount of depolarization seen in an action potential.

D) minimum depolarization needed to operate the voltage-gated sodium and potassium channels.

Action potentials move along axons A) more slowly in axons of large diameter as compared to those of small diameter. B) by the direct action of acetylcholine on the axonal membrane. C) by activating the sodium-potassium "pump" at each point along the axonal membrane. D) more rapidly in myelinated than in nonmyelinated axons. E) by reversing the concentration gradients for sodium and potassium ions.

D) more rapidly in myelinated than in nonmyelinated axons.

A chemical that affects neuronal function but is not stored in presynaptic vesicles is A) acetylcholine. B) epinephrine. C) endorphin. D) nitric oxide. E) GABA.

D) nitric oxide.

Scientists have tried raising endangered whooping cranes in captivity by using sandhill cranes as foster parents. This strategy is no longer used because A) fostered whooping crane chicks did not develop the necessary cues for migration. B) the fostered whooping cranes' critical period was variable such that different chicks imprinted on different "mothers." C) sandhill crane parents rejected their fostered whooping crane chicks soon after incubation. D) none of the fostered whooping cranes formed a mating pair-bond with another whooping crane. E) sandhill crane parents did not properly incubate whooping crane eggs.

D) none of the fostered whooping cranes formed a mating pair-bond with another whooping crane.

The "motor unit" in vertebrate skeletal muscle refers to A) one actin binding site and its myosin partner. B) one sarcomere and all of its actin and myosin filaments. C) one myofibril and all of its sarcomeres. D) one motor neuron and all of the muscle fibers on which it has synapses. E) an entire muscle.

D) one motor neuron and all of the muscle fibers on which it has synapses.

Imagine that you are designing an experiment aimed at determining whether the initiation of migratory behavior is largely under genetic control. Of the following options, the best way to proceed is to A) observe genetically distinct populations in the field and see if they have different migratory habits. B) perform within-population matings with birds from different populations that have different migratory habits. Do this in the laboratory and see if offspring display parental migratory behavior. C) bring animals into the laboratory and determine the conditions under which they become restless and attempt to migrate. D) perform within-population matings with birds from different populations that have different migratory habits. Rear the offspring in the absence of their parents and observe the migratory behavior of offspring. E) All of the options are equally productive ways to approach the question.

D) perform within-population matings with birds from different populations that have different migratory habits. Rear the offspring in the absence of their parents and observe the migratory behavior of offspring.

The evolution of mating systems is most likely affected by A) population density. B) territoriality. C) certainty of paternity. D) sexual dimorphism. E) None of the options is correct.

D) sexual dimorphism.

The operation of the sodium-potassium "pump" moves A) sodium and potassium ions into the cell. B) sodium and potassium ions out of the cell. C) sodium ions into the cell and potassium ions out of the cell. D) sodium ions out of the cell and potassium ions into the cell. E) sodium and potassium ions into the mitochondria.

D) sodium ions out of the cell and potassium ions into the cell.

Myelinated neurons are especially abundant in A) the gray matter of the brain and the white matter of the spinal cord. B) the white matter of the brain and the gray matter of the spinal cord. C) the gray matter of the brain and the gray matter of the spinal cord. D) the white matter in the brain and the white matter in the spinal cord. E) all areas of the brain and spinal cord.

D) the white matter in the brain and the white matter in the spinal cord.

The fastest possible conduction velocity of action potentials is observed in A) thin, nonmyelinated neurons. B) thin, myelinated neurons. C) thick, nonmyelinated neurons. D) thick, myelinated neurons.

D) thick, myelinated neurons.

An amino acid that operates at inhibitory synapses in the brain is A) acetylcholine. B) epinephrine. C) endorphin. D) nitric oxide. E) GABA.

E) GABA.

The major inhibitory neurotransmitter of the human brain is A) acetylcholine. B) epinephrine. C) glutamate. D) nitric oxide. E) GABA.

E) GABA.

A cation that is more abundant as a solute in the cytosol of a neuron than it is in the interstitial fluid outside the neuron is A) HCO3-. B) Cl-. C) Ca++. D) Na+. E) K+.

E) K+.

Skeletal, cardiac, and smooth muscle all have A) A bands and I bands. B) transverse tubules. C) gap junctions. D) motor units. E) thick and thin filaments.

E) thick and thin filaments.

Skeletal muscle contraction begins when calcium ions bind to A) energized cross-bridges. B) myosin. C) actin. D) tropomyosin. E) troponin.

E) troponin.

Animal communication involves what type of sensory information? A) visual B) auditory C) olfactory D) tactile E) visual, auditory, olfactory, and tactile

E) visual, auditory, olfactory, and tactile

The neuronal membrane is at its resting potential at label A) A. B) B. C) C. D) D. E) E.

E) E.

The point of connection between two communicating neurons is called the A) axon hillock. B) dendrite. C) synapse. D) cell body. E) glia.

C) synapse.

What probably explains why coastal and inland garter snakes react differently to banana slug prey? A) Ancestors of coastal snakes that could eat the abundant banana slugs had increased fitness. No such selection occurred inland, where banana slugs were absent. B) Banana slugs are camouflaged, and inland snakes, which have poorer vision than coastal snakes, are less able to see them. C) Garter snakes learn about prey from other garter snakes. Inland garter snakes have fewer types of prey because they are less social. D) Inland banana slugs are distasteful, so inland snakes learn to avoid them. Coastal banana slugs are palatable to garter snakes. E) Garter snakes learn to eat what their mothers eat. Coastal snake mothers happened to prefer slugs.

A) Ancestors of coastal snakes that could eat the abundant banana slugs had increased fitness. No such selection occurred inland, where banana slugs were absent.

How do altruistic behaviors arise through natural selection? A) By its actions, the altruist increases the likelihood that some of its genes will be passed on to the next generation. B) The altruist is appreciated by other members of the population because their survivability has been enhanced by virtue of the altruist's risky behavior. C) Animals that perform altruistic acts are allowed by their population to breed more, thereby passing on their behavior genes to future generations. D) Altruistic behaviors lower stress in populations, which increases the survivability of all the members of the population. E) All of the options are correct.

A) By its actions, the altruist increases the likelihood that some of its genes will be passed on to the next generation.

Which of the following is not required for a behavioral trait to evolve by natural selection? A) In each individual, the form of the behavior is determined entirely by genes. B) The behavior varies among individuals. C) An individual's reproductive success depends in part on how the behavior is performed. D) Some component of the behavior is genetically inherited. E) An individual's genotype influences its behavioral phenotype.

A) In each individual, the form of the behavior is determined entirely by genes.

Which of the following statements about the evolution of behavior is correct? A) Natural selection will favor behavior that enhances survival and reproduction. B) An animal may show behavior that minimizes reproductive fitness. C) If a behavior is less than optimal, it will eventually become optimal through natural selection. D) Innate behaviors can never be altered by natural selection. E) All of the statements are correct.

A) Natural selection will favor behavior that enhances survival and reproduction.

Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal? 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. E) An EPSP or IPSP is generated in the postsynaptic cell.

A) Voltage-gated calcium channels in the membrane open.

The cerebrospinal fluid is A) a filtrate of the blood. B) a secretion of glial cells. C) a secretion of interneurons. D) cytosol secreted from ependymal cells. E) secreted by the hypothalamus.

A) a filtrate of the blood.

The botulinum toxin reduces the synaptic release of A) acetylcholine. B) epinephrine. C) endorphin. D) nitric oxide. E) GABA.

A) acetylcholine.

The heart rate decreases in response to the arrival of A) acetylcholine. B) epinephrine. C) endorphin. D) nitric oxide. E) GABA.

A) acetylcholine.

Self-propagation and refractory periods are typical of A) action potentials. B) graded hyperpolarizations. C) excitatory postsynaptic potentials. D) threshold potentials. E) resting potentials.

A) action potentials.

Fred and Joe, two unrelated, mature male gorillas, encounter one another. Fred is courting a female. Fred grunts as Joe comes near. As Joe continues to advance, Fred begins drumming (pounding his chest) and bares his teeth. Joe then rolls on the ground on his back, gets up, and quickly leaves. This behavioral pattern is repeated several times during the mating season. Choose the most specific behavior described by this example. A) agonistic behavior B) territorial behavior C) learned behavior D) social behavior E) fixed action pattern

A) agonistic behavior

Choose the correct match of glial cell type and function. A) astrocytes—metabolize neurotransmitters and modulate synaptic effectiveness B) oligodendrocytes—produce the myelin sheaths of myelinated neurons in the peripheral nervous system C) microglia—produce the myelin sheaths of myelinated neurons in the central nervous system D) radial glia—the source of immunoprotection against pathogens. E) Schwann cells—provide nutritional support to nonmyelinated neurons

A) astrocytes—metabolize neurotransmitters and modulate synaptic effectiveness

Artificial electrical stimulation of a human's menthol-sensitive neurons would likely produce the sensation of A) cold temperature. B) hot temperature. C) tactile stimulus. D) odor of pepper. E) deep pressure.

A) cold temperature.

The cochlea is an organ of auditory transduction that contains A) fluid and cells that can undergo mechanosensory transduction. B) air and cells that produce wax. C) air and small bones that vibrate in response to sound waves. D) fluid with stacks of chemosensory cells. E) air and statocysts activated by movement.

A) fluid and cells that can undergo mechanosensory transduction.

The blood-brain barrier A) is formed by tight junctions. B) is formed by oligodendrocytes. C) tightly regulates the intracellular environment of the CNS. D) uses chemical signals to communicate with the spinal cord. E) provides support to the brain tissue.

A) is formed by tight junctions.

Ionotropic receptors are found at synapses operated via A) ligand-gated ion channels. B) second-messenger-gated ion channels. C) electrical synapses. D) inhibitory, but not excitatory, synapses. E) excitatory, but not inhibitory, synapses.

A) ligand-gated ion channels.

Statocysts contain cells that are A) mechanoreceptors used to detect orientation relative to gravity. B) chemoreceptors used in selecting migration routes. C) photoreceptors used in setting biological rhythms. D) thermoreceptors used in prey detection. E) chemoreceptors used in acid-base balance.

A) mechanoreceptors used to detect orientation relative to gravity.

In a relaxed skeletal muscle, actin is not chemically bound to A) myosin. B) troponin. C) tropomyosin. D) Z lines.

A) myosin.

Tastes and smells are distinct kinds of environmental information in that A) neural projections from taste receptors reach different parts of the brain than the neural projections from olfactory receptors. B) the single area of the cerebral cortex that receives smell and taste signals can distinguish tastes and smells by the pattern of action potentials received. C) tastant molecules are airborne, whereas odorant molecules are dissolved in fluids. D) distinguishing tastant molecules requires learning, whereas smell discrimination is an innate process. E) odorants bind to receptor proteins, but none of the tastant stimuli will bind to receptors.

A) neural projections from taste receptors reach different parts of the brain than the neural projections from olfactory receptors.

What type of signal is long-lasting and works at night? A) olfactory B) visual C) auditory D) tactile E) electrical

A) olfactory

You discover a rare new bird species, but you are unable to observe its mating behavior. You see that the male is large and ornamental compared with the female. On this basis, you can probably conclude that the species is A) polygamous. B) monogamous. C) polyandrous. D) promiscuous. E) agonistic.

A) polygamous.

An inhibitory postsynaptic potential (IPSP) occurs in a membrane made more permeable to A) potassium ions. B) sodium ions. C) calcium ions. D) ATP. E) all neurotransmitter molecules.

A) potassium ions.

The activation of the parasympathetic branch of the autonomic nervous system is associated with A) resting and digesting. B) release of epinephrine into the blood. C) increased metabolic rate. D) fight-or-flight responses. E) intensive aerobic exercise.

A) resting and digesting.

Immediately after putting on a shirt, your skin might feel itchy. However, this perception soon fades due to A) sensory adaptation. B) accommodation. C) the increase of transduction. D) reduced motor unit recruitment. E) reduced receptor amplification.

A) sensory adaptation.

Afferent neuronal systems include the A) sensory systems. B) peripheral nervous system. C) autonomic nervous system. D) parasympathetic nervous system. E) sympathetic nervous system.

A) sensory systems.

A stickleback fish will attack a fish model as long as the model has red coloring. What animal behavior idea is manifested by this observation? A) sign stimulus B) cognition C) imprinting D) classical conditioning E) operant conditioning

A) sign stimulus

Parental protective behavior in turkeys is triggered by the cheeping sound of young chicks. What term best applies to this behavior? A) sign stimulus B) cognition C) imprinting D) classical conditioning E) operant conditioning

A) sign stimulus

Preparation for the fight-or-flight response includes activation of the ________ nervous system. A) sympathetic B) somatic C) central D) visceral E) parasympathetic

A) sympathetic

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

In a simple synapse, neurotransmitter chemicals are received by 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.

The calcium ions released into the cytosol during excitation of skeletal muscle bind to A) troponin. B) tropomyosin. C) actin. D) myosin. E) transverse tubules.

A) troponin.

The muscles of a recently deceased human can remain in a contracted state, termed rigor mortis, for several hours, due to the lack of A) phosphorylated myosin. B) ATP needed to break actin-myosin bonds. C) calcium ions needed to bind to troponin. D) oxygen supplies needed for myoglobin. E) sodium ions needed to fire action potentials.

B) ATP needed to break actin-myosin bonds.

In Figure 38.1, which letter points to the hypothalamus? A) A B) B C) C D) D E) E

B) B

Which area in Figure 39.1 has only overlapping actin and myosin filaments? A) A B) B C) C D) D E) E

B) B

The membrane's permeability to sodium ions is at its maximum at label A) A. B) B. C) C. D) D. E) E.

B) B.

A cage containing male mosquitoes has a small earphone placed on top, through which the sound of a female mosquito is played. All the males immediately fly to the earphone and go through all of the steps of copulation. What is the best explanation for this behavior? A) The males learned to associate the sound with females. B) Copulation is a fixed action pattern, and the female flight sound is a sign stimulus that initiates it. C) The sound from the earphone irritated the male mosquitoes, causing them to attempt to sting it. D) The reproductive drive is so strong that when males are deprived of females, they will attempt to mate with anything that has even the slightest female characteristic. E) Through classical conditioning, the male mosquitoes have associated the inappropriate stimulus from the earphone with the normal response of copulation.

B) Copulation is a fixed action pattern, and the female flight sound is a sign stimulus that initiates it.

ATP hydrolysis directly powers the movement of A) K+ out of cells. B) Na+ out of cells. C) Na+ into cells. D) Ca++ into cells. E) Cl— into cells.

B) Na+ out of cells.

Why are action potentials usually conducted in one direction? A) The nodes of Ranvier conduct potentials in one direction. B) The brief refractory period prevents reopening of voltage gated Na+ channels. C) The axon hillock has a higher membrane potential than the terminals of the axon. D) Ions can flow along the axon in only one direction. E) Voltage-gated channels for both Na+ and K+ open in only one direction.

B) The brief refractory period prevents reopening of voltage gated Na+ channels.

During a field trip, an instructor touched a moth resting on a tree trunk. The moth raised its forewings to reveal large eyespots on its hind wings. The instructor asked why the moth lifted its wings. One student answered that sensory receptors had fired and triggered a neuronal reflex culminating in the contraction of certain muscles. A second student responded that the behavior might frighten predators. Which statement best describes these explanations? A) The first explanation is correct, but the second is incorrect. B) The first explanation refers to proximate causation, whereas the second refers to ultimate causation. C) The first explanation is biological, whereas the second is philosophical. D) The first explanation is testable as a scientific hypothesis, whereas the second is not. E) Both explanations are reasonable and simply represent a difference of opinion.

B) The first explanation refers to proximate causation, whereas the second refers to ultimate causation.

The suprachiasmatic nuclei are found in the A) thalamus. B) hypothalamus. C) epithalamus. D) amygdala. E) Broca's area.

B) hypothalamus.

One way to understand how early environment influences differing behaviors in similar species is through the "cross-fostering" experimental technique. Suppose that the curly- whiskered mud rat differs from the bald mud rat in several ways, including being much more aggressive. How would you set up a cross-fostering experiment to determine if environment plays a role in the curly-whiskered mud rat's aggression? A) You would cross curly-whiskered mud rats and bald mud rats and hand-rear the offspring to see if any grew up to be aggressive. B) You would place newborn curly-whiskered mud rats with bald mud rat parents, place newborn bald mud rats with curly-whiskered mud rat parents, and let some mud rats of both species be raised by their own species. Then you would compare the outcomes. C) You would remove the offspring of curly-whiskered mud rats and bald mud rats from their parents, raise them in the same environment, and then compare the outcomes. D) You would see if curly-whiskered mud rats bred true for aggression. E) You would replace normal newborn mud rats with deformed newborn mud rats to see if it triggered an altruistic response.

B) You would place newborn curly-whiskered mud rats with bald mud rat parents, place newborn bald mud rats with curly-whiskered mud rat parents, and let some mud rats of both species be raised by their own species. Then you would compare the outcomes.

Myasthenia gravis is a form of muscle paralysis in which A) motor neurons lose their myelination and the ability to rapidly fire action potentials. B) acetylcholine receptors are destroyed by an overactive immune system. C) ATP production becomes uncoupled from mitochondrial electron transport. D) the spinal cord is infected with a virus that attacks muscle stretch receptors. E) troponin molecules become unable to bind calcium ions.

B) acetylcholine receptors are destroyed by an overactive immune system.

An example of ligand-gated ion channels is 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. E) graded hyperpolarization.

B) acetylcholine receptors at the neuromuscular junction.

Pair-bonding in a population of prairie voles can be prevented by A) the ensuing confusion caused by introducing meadow voles. B) administering a drug that inhibits the brain receptor for vasopressin in the CNS of males. C) administering a drug that turns on ADH receptor sites in male voles. D) dying the coat color from brown to blond in either male or female prairie voles. E) allowing the population size to reach critically low levels.

B) administering a drug that inhibits the brain receptor for vasopressin in the CNS of males.

Functionally, which cellular location is the neuron's "decision-making site" as to whether or not an action potential will be initiated? A) axonal membranes B) axon hillocks C) dendritic membranes D) mitochondrial membranes E) presynaptic membranes

B) axon hillocks

During the contraction of a vertebrate skeletal muscle fiber, calcium ions A) break cross-bridges by acting as a cofactor in the hydrolysis of ATP. B) bind with troponin, changing its shape so that the myosinbinding sites on actin are exposed. C) transmit action potentials from the motor neuron to the muscle fiber. D) spread action potentials through the T tubules. E) re-establish the polarization of the plasma membrane following an action potential.

B) bind with troponin, changing its shape so that the myosinbinding sites on actin are exposed.

Calcium ions initiate sliding of filaments in skeletal muscles by A) breaking the actin-myosin cross-bridges. B) binding to the troponin complex, which then relocates tropomyosin. C) transmitting action potentials across the neuromuscular junction. D) spreading action potentials through the T tubules. E) reestablishing the resting membrane potential following an action potential.

B) binding to the troponin complex, which then relocates tropomyosin.

The structure pictured in Figure 39.1 is found in A) skeletal muscles and smooth muscles. B) cardiac muscles and skeletal muscles. C) smooth muscles and cardiac muscles. D) smooth muscles, skeletal muscles, and cardiac muscles. E) smooth muscles.

B) cardiac muscles and skeletal muscles.

The proximate causes of behavior are interactions with the environment, but behavior is ultimately shaped by A) hormones. B) evolution. C) sexuality. D) pheromones. E) the nervous system.

B) evolution.

Sustained muscle contraction without relaxation between successive stimuli is called A) tonus. B) fused tetanus. C) an all-or-none response. D) fatigue. E) a spasm.

B) fused tetanus.

The presence of altruistic behavior is most likely due to kin selection, a theory maintaining that A) aggression between sexes promotes the survival of the fittest individuals. B) genes enhance the survival of copies of themselves by directing organisms to assist others who share those genes. C) companionship is advantageous to animals because in the future they can help each other. D) critical thinking abilities are normal traits for animals and they have arisen, like other traits, through natural selection. E) natural selection has generally favored the evolution of exaggerated aggressive and submissive behaviors to resolve conflict without grave harm to participants.

B) genes enhance the survival of copies of themselves by directing organisms to assist others who share those genes.

Compared to viewing a distant object, viewing an object held within 5 cm of the eye requires a lens that A) has been flattened, as a result of contraction of the ciliary muscles. B) has been made more spherical, as a result of contraction of the ciliary muscles. C) has been flattened, as a result of relaxation of the ciliary muscles. D) has been made more spherical, as a result of relaxation of the ciliary muscles. E) does not change its shape.

B) has been made more spherical, as a result of contraction of the ciliary muscles.

Artificial electrical stimulation of a human's capsaicin-sensitive neurons would likely produce the sensation of A) cold temperature. B) hot temperature. C) tactile stimulus. D) odor of pepper. E) deep pressure.

B) hot temperature.

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

B) hyperpolarization of the neuron.

Central coordination of vertebrate biological rhythms in physiology and behavior resides in the A) pituitary gland. B) hypothalamus. C) cerebrum. D) cerebellum. E) thalamus.

B) hypothalamus.

According to Hamilton's rule, A) natural selection does not favor altruistic behavior that causes the death of the altruist. B) natural selection favors altruistic acts when the resulting benefit to the recipient, corrected for relatedness, exceeds the cost to the altruist. C) natural selection is more likely to favor altruistic behavior that benefits an offspring than altruistic behavior that benefits a sibling. D) the effects of kin selection are larger than the effects of direct natural selection on individuals. E) altruism is always reciprocal.

B) natural selection favors altruistic acts when the resulting benefit to the recipient, corrected for relatedness, exceeds the cost to the altruist.

Proteins coded by a very large family of related genes are active in the sensory transduction of A) gustatory stimuli. B) olfactory stimuli. C) visual stimuli. D) auditory stimuli. E) stimuli related to the position of the head.

B) olfactory stimuli.

An action potential can start in the middle of an axon and proceed in both opposite directions when A) the neuron is an inhibitory neuron and operating normally. B) only the middle section of the axon has been artificially stimulated by an electrode. C) the dendritic region fires an action potential. D) it is in its typical refractory state. E) its membrane potential is above the threshold.

B) only the middle section of the axon has been artificially stimulated by an electrode.

Karl von Frisch demonstrated that European honeybees communicate the location of a distant food source by A) performing a short, straight run during a waggle dance. B) performing a long, straight run during a waggle dance. C) performing a round dance with fast rotations. D) emanating minute amounts of stimulus pheromone. E) varying wing vibration frequency.

B) performing a long, straight run during a waggle dance.

Upon returning to its hive, a European honeybee communicates to other worker bees the presence of a nearby food source it has discovered by A) vibrating its wings at varying frequencies. B) performing a round dance. C) performing a waggle dance. D) visual cues. E) All options are correct.

B) performing a round dance.

In a cephalized invertebrate, the system that transmits "efferent" impulses from the anterior ganglion to distal segments is the A) central nervous system. B) peripheral nervous system. C) autonomic nervous system. D) parasympathetic nervous system. E) sympathetic nervous system.

B) peripheral nervous system.

A toxin that binds specifically to voltage-gated sodium channels in axons would be expected to A) prevent the hyperpolarization phase of the action potential. B) prevent the depolarization phase of the action potential. C) prevent graded potentials. D) increase the release of neurotransmitter molecules. E) have most of its effects on the dendritic region of a neuron.

B) prevent the depolarization phase of the action potential.

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

B) refractory.

The generation of action potentials in olfactory neurons initiated by odors drawn into the nasal cavity is an example of A) perception. B) sensory transduction. C) sensory adaptation. D) habituation. E) lateral inhibition.

B) sensory transduction.

In the territorial behavior of the stickleback fish, the red belly of one male that elicits attack from another male is functioning as a(n) A) pheromone. B) sign stimulus. C) fixed action pattern. D) search image. E) imprint stimulus.

B) sign stimulus.

If the following events are arranged in the order in which they occur for an animal hiding in response to seeing a predator, which is the fourth event in the series? A) signaling by an afferent PNS neuron B) signaling by an efferent PNS neuron C) information processing in the CNS D) activation of a sensory receptor E) activation of a motor system

B) signaling by an efferent PNS neuron

Although the membrane of a "resting" neuron is highly permeable to potassium ions, its membrane potential does not exactly match the equilibrium potential for potassium because the neuronal membrane is also A) fully permeable to sodium ions. B) slightly permeable to sodium ions. C) fully permeable to calcium ions. D) impermeable to sodium ions. E) highly permeable to chloride ions.

B) slightly permeable to sodium ions.

When several EPSPs arrive at the axon hillock from different dendritic locations, depolarizing the postsynaptic cell to threshold for an action potential, this is an example of A) temporal summation. B) spatial summation. C) tetanus. D) the refractory state. E) an action potential with an abnormally high peak of depolarization.

B) spatial summation.

The structure diagrammed in Figure 38.2 is the A) neuromast. B) statocyst. C) taste bud. D) ommatidium. E) olfactory bulb.

B) statocyst.

The sand grains or other dense materials resting on mechanoreceptors used by most invertebrates to sense gravity are called A) cochlea. B) statoliths. C) stapes. D) pinnae. E) antennae.

B) statoliths.

The correct sequence of sensory processing is A) sensory adaptation → stimulus reception → sensory transduction → sensory perception. B) stimulus reception → sensory transduction → sensory perception → sensory adaptation. C) sensory perception → stimulus reception → sensory transduction → sensory adaptation. D) sensory perception → sensory transduction → stimulus reception → sensory adaptation. E) stimulus reception → sensory perception → sensory adaptation → sensory transduction.

B) stimulus reception → sensory transduction → sensory perception → sensory adaptation.

The "undershoot" phase of after-hyperpolarization is due to A) slow opening of voltage-gated sodium channels. B) sustained opening of voltage-gated potassium channels. C) rapid opening of voltage-gated calcium channels. D) slow restorative actions of the sodium-potassium ATPase. E) ions that move away from their open ion channels.

B) sustained opening of voltage-gated potassium channels.

The divisions of the nervous system that have antagonistic, or opposing, actions are the A) motor and sensory systems. B) sympathetic and parasympathetic systems. C) presynaptic and postsynaptic membranes. D) forebrain and hindbrain. E) central nervous system and peripheral nervous system.

B) sympathetic and parasympathetic systems.

Choose the correct sequence of the following events leading to the sensory processing of a stimulus. 1. transmission 2. transduction 3. integration 4. amplification A) 1 → 2 → 3 → 4 B) 1 → 4 → 2 → 3 C) 2 → 4 → 1 → 3 D) 3 → 1 → 2 → 4 E) 3 → 1 → 4 → 2

C) 2 → 4 → 1 → 3

The system that modulates excitation and inhibition of the smooth and cardiac muscles of the digestive, cardiovascular, and excretory systems is the A) central nervous system. B) motor system. C) autonomic nervous system. D) parasympathetic nervous system. E) sympathetic nervous system.

C) autonomic nervous system.

The behavior of most animals is influenced by the periods of daylight and darkness in the environment. Fiddler crabs' courtship behaviors are instead synchronized by the 29 1/2-day cycle of the moon. What is the adaptive significance of using lunar cues? A) The fiddler crab courtship ritual is highly visual, so individuals need the light of the full moon to be able to observe courtship displays. B) Egg maturation in fiddler crab females takes 29 1/2 days. C) By courting at the full and new moon, fiddler crabs link their reproduction to the times of the highest tides that disperse their larvae to safer, deeper waters. D) The algae that larval fiddler crabs consume for energy and metabolism bloom on a monthly cycle, so recently hatched larvae have plenty to eat during a crucial time of their lives. E) It takes about 29 days for a fiddler crab to reach sexual maturity.

C) By courting at the full and new moon, fiddler crabs link their reproduction to the times of the highest tides that disperse their larvae to safer, deeper waters.

A human baby performs a sucking behavior perfectly when it is put in the presence of the nipple of its mother's breast. A) A B) B C) C D) D E) E

C) C

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

C) C.

The period in which voltage-gated potassium channels are open and hyperpolarization has yet to occur is at label A) A. B) B. C) C. D) D. E) E.

C) C.

In Belding's ground squirrels, it is mostly the females that behave altruistically by sounding alarm calls. What is the likely reason for this distinction? A) Males have smaller vocal cords and are less likely to make sounds. B) Females invest more in foraging and food stores, so they are more defensive. C) Females settle in the area in which they were born, so the alarm is warning kin. D) The sex ratio is biased. E) Males forage in areas separate from females; therefore, alarm calls are useless.

C) Females settle in the area in which they were born, so the alarm is warning kin.

What is the fitness benefit of polygamy in birds that rear young that are precocious (develop and mature rapidly)? A) Females will copulate with many males to ensure that all of their eggs are fertilized. B) Females don't have to decide on one mate, and can copulate with as many males as they deem worthy to share their genes with in reproduction. C) Fit males don't have to help feed and rear young and can spend this time seeking out and mating with many females. D) Females don't have to spend time rearing young and can mate and rear additional broods during a breeding season. E) Both males and females spend little time with courtship and brood-rearing, and don't tax their own physiology, so they can breed again in subsequent breeding seasons.

C) Fit males don't have to help feed and rear young and can spend this time seeking out and mating with many females.

A female cat in heat urinates more often and in many places. Male cats are attracted to the urine deposits. Which of the following is a proximate cause of this increased urination? A) It announces to the males that she is in heat. B) Female cats that did this in the past attracted more males. C) It is a result of hormonal changes associated with her reproductive cycle. D) The female cat learned the behavior from observing other cats. E) All of the options are ultimate causes of behavior.

C) It is a result of hormonal changes associated with her reproductive cycle.

Cephalization, the clustering of neurons and interneurons in the anterior part of the animal, is apparent in A) Hydra. B) cnidarians. C) Planaria. D) sea stars. E) invertebrate animals with radial symmetry.

C) Planaria.

A female cat in heat urinates more often and in many places. Male cats congregate near the urine deposits and fight with each other. Which of the following would be an ultimate cause of the male cats' response to the female's urinating behavior? A) The males have learned to recognize the specific odor of the urine of a female in heat. B) When the males smelled the odor, various neurons in their brains were stimulated. C) Responding to the odor means locating reproductively receptive females. D) Male cats' hormones are triggered by the odor released by the female. E) The odor serves as a releaser for the instinctive behavior of the males.

C) Responding to the odor means locating reproductively receptive females.

What happens when a resting neuron's membrane depolarizes? A) There is a net diffusion of Na+ out of the cell. B) The equilibrium potential for K+ (EK) becomes more positive. C) The neuron's membrane voltage becomes more positive. D) The neuron is less likely to generate an action potential. E) The cell's inside is more negative than the outside.

C) The neuron's membrane voltage becomes more positive.

Umami perception would be stimulated by A) sugar water. B) chocolate milk. C) a savory and rich cheese. D) acidic orange juice. E) salt water.

C) a savory and rich cheese.

A given photon of light may trigger an action potential with thousands of times more energy because the signal strength is magnified by A) the receptor. B) a G protein. C) an enzyme-catalyzed reaction. D) sensory adaptation. E) triggering several receptors at once.

C) an enzyme-catalyzed reaction.

Which of the following does not have a coefficient of relatedness of 0.5? A) a father to his daughter B) a mother to her son C) an uncle to his nephew D) a brother to his brother E) a sister to her brother

C) an uncle to his nephew

A common feature of action potentials is that they A) cause the membrane to hyperpolarize and then depolarize. B) can undergo temporal and spatial summation. C) are triggered by a depolarization that reaches threshold. D) move at the same speed along all axons. E) require the diffusion of Na+ and K+ through ligand-gated channels to propagate.

C) are triggered by a depolarization that reaches threshold.

Animals that help other animals of the same species A) have excess energy reserves. B) are bigger and stronger than the other animals. C) are usually related to the other animals. D) are always male. E) have defective genes controlling their behavior.

C) are usually related to the other animals.

What type of signal is brief and can work among obstructions at night? A) olfactory B) visual C) auditory D) tactile E) magnetic

C) auditory

The central nervous system is lacking in animals that have A) a complete gut. B) bilateral symmetry. C) radial symmetry. D) a closed circulatory system. E) excitable membranes.

C) radial symmetry.

Imagine you are resting comfortably on a sofa after dinner. This could be described as a state with A) increased activity in the sympathetic, parasympathetic, and enteric nervous systems. B) decreased activity in the sympathetic, parasympathetic, and enteric nervous systems. C) decreased activity in the sympathetic nervous system, and increased activity in the parasympathetic and enteric nervous systems. D) increased activity in the sympathetic nervous system, and decreased activity in the parasympathetic and enteric nervous systems. E) increased activity in the sympathetic nervous system, decreased activity in the parasympathetic nervous system, and increased activity in the enteric nervous system.

C) decreased activity in the sympathetic nervous system, and increased activity in the parasympathetic and enteric nervous systems.

Receptors for neurotransmitters are of primary functional importance in assuring one-way synaptic transmission because they are mostly found on the A) axonal membrane. B) axon hillock. C) dendritic membrane. D) mitochondrial membrane. E) presynaptic membrane.

C) dendritic membrane.

Action potentials in the heart move from one contractile cell to the next via A) chemical synapses using acetylcholine. B) chemical synapses using norepinephrine. C) electrical synapses using gap junctions. D) myelinated motor neurons. E) nonmyelinated motor neurons.

C) electrical synapses using gap junctions.

A neuropeptide that might function as a natural analgesic is A) acetylcholine. B) epinephrine. C) endorphin. D) nitric oxide. E) GABA.

C) endorphin.

A skeletal muscle deprived of adequate ATP supplies will A) immediately relax. B) release all actin—myosin bonds. C) enter a state where actin and myosin are unable to separate. D) fire many more action potentials than usual and enter a state of "rigor." E) sequester all free calcium ions into the sarcoplasmic reticulum.

C) enter a state where actin and myosin are unable to separate.

The membrane potential that exactly offsets an ion's concentration gradient is called the A) graded potential. B) threshold potential. C) equilibrium potential. D) action potential. E) inhibitory postsynaptic potential.

C) equilibrium potential.

Cerebrospinal fluid can be described as all of the following except A) functioning in transport of nutrients and hormones through the brain. B) a product of the filtration of blood in the brain. C) formed from layers of connective tissue. D) functioning to cushion the brain. E) filling cavities in the brain called ventricles.

C) formed from layers of connective tissue.

Neural transmission across a mammalian synapse is accomplished by A) the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron. B) impulses traveling as electrical currents across the synapse. C) impulses causing the release of a chemical signal and its diffusion across the synapse. D) impulses ricocheting back and forth across the synapse. E) the movement of calcium ions from the presynaptic into the postsynaptic neuron.

C) impulses causing the release of a chemical signal and its diffusion across the synapse.

Most of the neurons in the human brain are A) sensory neurons. B) motor neurons. C) interneurons. D) auditory neurons. E) peripheral neurons.

C) interneurons.

The observation that the acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it is an example of a A) voltage-gated sodium channel. B) voltage-gated potassium channel. C) ligand-gated sodium channel. D) second-messenger-gated sodium channel. E) chemical that inhibits action potentials.

C) ligand-gated sodium channel.

Which sensory distinction is not encoded by a difference in which axon transfers the information to the brain? A) white and red B) red and green C) loud and faint D) salty and sweet E) spicy and cool

C) loud and faint

Curare, a substance that blocks the acetylcholine receptors on skeletal muscle, will cause A) rapid muscle twitches. B) sustained muscle contraction (tetanus). C) muscle relaxation. D) specific disruption of blood pressure and digestive functions. E) no effect in the absence of acetylcholinesterase.

C) muscle relaxation.

Displays of nocturnal mammals are usually A) visual and auditory. B) tactile and visual. C) olfactory and auditory. D) visual and olfactory. E) tactile and auditory.

C) olfactory and auditory.

Two fundamental principles that characterize gated ion channels in the neuronal membrane are that the channels A) are always open, but the concentration gradients of ions frequently change. B) are always closed, but ions move closer to the channels during excitation. C) open and close depending on stimuli and are specific as to which ion can traverse them. D) open and close depending on chemical messengers and are nonspecific as to which ion can traverse them. E) open in response to stimuli, and then close simultaneously, in unison.

C) open and close depending on stimuli and are specific as to which ion can traverse them.

Two fundamental concepts about the ion channels of a "resting" neuron are that the channels A) are always open, but the concentration gradients of ions frequently change. B) are always closed, but ions move closer to the channels during excitation. C) open and close depending on stimuli, and are specific as to which ion can traverse them. D) open and close depending on chemical messengers, and are nonspecific as to which ion can traverse them. E) open in response to stimuli, and then close simultaneously, in unison.

C) open and close depending on stimuli, and are specific as to which ion can traverse them.

In the sequence of permeability changes for a complete action potential, the first of these events that occurs is the A) activation of the sodium-potassium "pump." B) inhibition of the sodium-potassium "pump." C) opening of voltage-gated sodium channels. D) closing of voltage-gated potassium channels. E) opening of voltage-gated potassium channels.

C) opening of voltage-gated sodium channels.

Circannual rhythms in birds are influenced by A) periods of food availability. B) reproductive readiness. C) periods of daylight and darkness. D) magnetic fields. E) lunar cycles.

C) periods of daylight and darkness.

A chemical produced by an animal that serves as a communication to another animal of the same species is called a(n) A) sign stimulus. B) inducer. C) pheromone. D) imprinter. E) agonistic promoter.

C) pheromone.

Action potentials are normally carried in only one direction: from the axon hillock toward the axon terminals. If you experimentally depolarize the middle of the axon to threshold, using an electronic probe, then A) no action potential will be initiated. B) an action potential will be initiated and proceed only in the normal direction toward the axon terminal. C) an action potential will be initiated and proceed only back toward the axon hillock. D) two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock. E) an action potential will be initiated, but it will die out before it reaches the axon terminal.

D) two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock.

Opening all of the sodium channels, with all other ion channels closed—which is an admittedly artificial setting—on an otherwise typical neuron should move its membrane potential to A) -90 mV. B) -70 mV. C) 0 mV. D) +30 mV. E) +62 mV.

E) +62 mV.

Which of the following is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber? 1. Tropomyosin shifts and unblocks the cross-bridge binding sites. 2. Calcium is released and binds to the troponin complex. 3. Transverse tubules depolarize the sarcoplasmic reticulum. 4. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP. 5. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane. A) 1 → 2 → 3 → 4 → 5 B) 2 → 1 → 3 → 5 → 4 C) 2 → 3 → 4 → 1 → 5 D) 5 → 3 → 1 → 2 → 4 E) 5 → 3 → 2 → 1 → 4

E) 5 → 3 → 2 → 1 → 4

Neurotransmitters affect postsynaptic cells by A) initiating signal transduction pathways in the cells. B) causing molecular changes in the cells. C) affecting ion-channel proteins. D) altering the permeability of the cells. E) All of these options are correct.

E) All of these options are correct.

Animals use pheromones to communicate A) reproductive readiness. B) species recognition. C) gender recognition. D) danger. E) All options are correct.

E) All options are correct.

Upon observing a golden eagle flying overhead, a sentry prairie dog gives a warning call to other foraging members of the prairie dog community. A) A B) B C) C D) D E) E

E) E

Which of the following statements is true about the certainty of paternity? A) Young or eggs laid by a female are likely to contain the same genes as another female's eggs in a population of birds. B) The certainty of paternity is high in most species with internal fertilization because the acts of mating and birth are separated by time. C) Males that guard females they have mated with are certain of their paternity. D) The certainty of paternity is low when egg laying and mating occur together, as in external fertilization. E) Paternal behavior exists because it has been reinforced over generations by natural selection.

E) Paternal behavior exists because it has been reinforced over generations by natural selection.

Calcium ions regulate contraction of smooth muscle cells by binding to A) troponin. B) tropomyosin. C) actin. D) myosin. E) calmodulin.

E) calmodulin.

The binding of calcium to the troponin complex A) activates myosin kinase, causing phosphorylation of myosin heads. B) disrupts cross-bridges, allowing filaments to slide past each other. C) allows tropomyosin to bind actin. D) opens ion channels, allowing sodium to rush into the muscle cells. E) causes tropomyosin to shift position, exposing myosin bind sites on actin.

E) causes tropomyosin to shift position, exposing myosin bind sites on actin.

Suppose a particular neurotransmitter causes an IPSP in postsynaptic cell X and an EPSP in postsynaptic cell Y. A likely explanation is that A) the threshold value in the postsynaptic membrane is different for cell X and cell Y. B) cell Y forms chemical synapses, whereas cell X forms electrical synapses. C) the axon of cell X is myelinated, but that of cell Y is not. D) only cell Y produces an enzyme that terminates the activity of the neurotransmitter. E) cells X and Y express different receptor molecules for this particular neurotransmitter.

E) cells X and Y express different receptor molecules for this particular neurotransmitter.

The activity of acetylcholine in a synapse is terminated by its A) active transport across the presynaptic membrane. B) diffusion across the presynaptic membrane. C) active transport across the postsynaptic membrane. D) diffusion across the postsynaptic membrane. E) degradation by a hydrolytic enzyme on the postsynaptic membrane.

E) degradation by a hydrolytic enzyme on the postsynaptic membrane.

The release of acetylcholine from the terminal of a motor neuron is most directly linked to the A) entry of potassium into the axon terminal. B) exit of potassium from the axon terminal. C) entry of sodium into the axon terminal. D) exit of sodium from the axon terminal. E) entry of calcium into the axon terminal.

E) entry of calcium into the axon terminal.

Neurotransmitters are released from axon terminals via A) osmosis. B) active transport. C) diffusion. D) transcytosis. E) exocytosis.

E) exocytosis.

Neurotransmitters categorized as inhibitory are expected to A) act independently of their receptor proteins. B) close potassium channels. C) open sodium channels. D) close chloride channels. E) hyperpolarize the membrane.

E) hyperpolarize the membrane.

A simple nervous system A) must include chemical senses, mechanoreception, and vision. B) includes a minimum of 12 effector neurons. C) has information flow in only one direction: toward an integrating center. D) has information flow in only one direction: away from an integrating center. E) includes sensory information, an integrating center, and effectors.

E) includes sensory information, an integrating center, and effectors.

A graded hyperpolarization of a membrane can be induced by 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+.

E) increasing its membrane's permeability to K+.

Saltatory conduction is a term applied to A) conduction of impulses across electrical synapses. B) an action potential that skips the axon hillock in moving from the dendritic region to the axon terminal. C) the rapid movement of an action potential reverberating back and forth along a neuron. D) jumping from one neuron to an adjacent neuron. E) jumping from one node of Ranvier to the next in a myelinated neuron.

E) jumping from one node of Ranvier to the next in a myelinated neuron.

Compared to oxidative skeletal muscle fibers, those classified as glycolytic typically have A) a higher concentration of myoglobin. B) a higher density of mitochondria. C) a darker visual appearance. D) a smaller diameter. E) less resistance to fatigue.

E) less resistance to fatigue.

A ligand for the umami receptor in the sense of taste is A) glucose. B) sodium ions. C) potassium ions. D) hydrogen ions. E) monosodium glutamate.

E) monosodium glutamate.

The contraction of skeletal muscles is based on A) actin filaments coiling up to become shorter. B) myosin filaments coiling up to become shorter. C) actin and myosin filaments both coiling up to become shorter. D) actin cross-bridges binding to myosin and transitioning from a high-energy to a low-energy state. E) myosin cross-bridges binding to actin and transitioning from a high-energy to a low-energy state.

E) myosin cross-bridges binding to actin and transitioning from a high-energy to a low-energy state.

The "selectivity" of a particular ion channel refers to its A) permitting passage by positive but not negative ions. B) permitting passage by negative but not positive ions. C) ability to change its size depending on the ion needing transport. D) binding with only one type of neurotransmitter. E) permitting passage only to a specific ion.

E) permitting passage only to a specific ion.

The mating system in which females are more ornamented than males is A) monogamy. B) promiscuity. C) polygamy. D) polygyny. E) polyandry.

E) polyandry.

The surface on a neuron that discharges the contents of synaptic vesicles is the A) dendrite. B) axon hillock. C) node of Ranvier. D) postsynaptic membrane. E) presynaptic membrane.

E) presynaptic membrane.

Injury to just the hypothalamus would most likely disrupt A) short-term memory. B) coordination during locomotion. C) executive functions, such as decision making. D) sorting of sensory information. E) regulation of body temperature.

E) regulation of body temperature.

Sensory transduction of light/dark information in the vertebrate retina is accomplished by A) ganglion cells. B) amacrine cells. C) bipolar cells. D) horizontal cells. E) rods and cones.

E) rods and cones.