Experiments with genetically altered mice showed that the mice would consume abnormally high amounts of bitter-tasting compounds in water after their

Experiments with genetically altered mice showed that the mice would consume abnormally high amounts of bitter-tasting compounds in water after their 

A) hormone receptors for digestive hormones were reduced or eliminated, showing that bitter tastes are reinforced by digestive responses.
B) salt-taste cells were altered to express receptors for bitter tastants, suggesting that animals have unregulated salt appetites.
C) visual sense was reduced or eliminated, suggesting that mice learn visual cues about bitter tastes.
D) olfactory sense was reduced or eliminated, suggesting that mice learn odor cues about bitter tastes.
E) sweet-taste cells were altered to express receptors for bitter tastants, suggesting that the sensation of taste depends only on which taste cell is stimulated.





Answer: E

Among these choices, the most energetically efficient locomotion per unit mass is likely

Among these choices, the most energetically efficient locomotion per unit mass is likely 

A) running by a 50-gram rodent.
B) running by a 40-kg ungulate.
C) flying by a 100-g bird.
D) swimming by a 10-g minnow (bony fish).
E) swimming by a 100-kg tuna (bony fish).





Answer: E

A ball-and-socket joint connects

A ball-and-socket joint connects 

A) the radius to the ulna.
B) the radius to the humerus.
C) the ulna to the humerus.
D) the humerus to the scapula.
E) the radius to the scapula.






Answer: D

An endoskeleton is the primary body support for the

An endoskeleton is the primary body support for the 

A) annelids, including earthworms.
B) insects, including beetles.
C) cartilaginous fishes, including sharks.
D) bivalves, including clams.
E) crustaceans, including lobsters.






Answer: C

Chitin is a major component of

Chitin is a major component of 

A) the skeleton of mammals.
B) the hydrostatic skeletons of earthworms.
C) the exoskeleton of insects.
D) the body hairs of mammals.
E) the skeleton in birds.







Answer: C

The hydrostatic skeleton of the earthworm allows it to move around in its environment by

The hydrostatic skeleton of the earthworm allows it to move around in its environment by 

A) walking on its limbs.
B) crawling with its feet.
C) swimming with its setae.
D) using peristaltic contractions of its circular and longitudinal muscles.
E) alternating contractions and relaxations of its flagellae.






Answer: D

Action potentials in the heart move from one contractile cell to the next via

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) non-myelinated motor neurons.





Answer: C

Calcium ions regulate contraction of smooth muscle cells by binding to

Calcium ions regulate contraction of smooth muscle cells by binding to 

A) troponin.
B) tropomyosin.
C) actin.
D) myosin.
E) calmodulin.






Answer: E

Skeletal, cardiac, and smooth muscle all have

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.







Answer: E

Sustained muscle contraction without relaxation between successive stimuli is called

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.






Answer: B 

The lumen of the transverse tubules of skeletal muscles contains

The lumen of the transverse tubules of skeletal muscles contains 

A) extracellular fluid.
B) cytosol.
C) actin.
D) myosin.
E) sarcomeres.





Answer: A

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.

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




Answer: E

A skeletal muscle with abnormally low levels of calcium ions would be impaired in

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.





Answer: D

Skeletal muscle contraction begins when calcium ions bind to

Skeletal muscle contraction begins when calcium ions bind to 

A) energized cross-bridges.
B) myosin.
C) actin.
D) tropomyosin.
E) troponin.





Answer: E

In a relaxed skeletal muscle, actin is not chemically bound to

In a relaxed skeletal muscle, actin is not chemically bound to 

A) myosin.
B) troponin.
C) tropomyosin.
D) Z lines






Answer: A

Muscle cells are stimulated by neurotransmitters released from the synaptic terminals of

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.






Answer: B

Calcium ions initiate sliding of filaments in skeletal muscles by

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.






Answer: B

The muscles of a recently deceased human can remain in a contracted state, termed rigor mortis, for several hours, due to the lack of

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.





Answer: B

The "motor unit" in vertebrate skeletal muscle refers to

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.





Answer: D

The calcium ions released into the cytosol during excitation of skeletal muscle bind to

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.






Answer: A

Most of the ATP supplies for a skeletal muscle undergoing 1 hour of sustained exercise come from

Most of the ATP supplies for a skeletal muscle undergoing 1 hour of sustained exercise come from

A) creatine phosphate.
B) glycolysis.
C) substrate phosphorylation.
D) oxidative phosphorylation.
E) de novo synthesis.







Answer: D

A skeletal muscle deprived of adequate ATP supplies will

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.





Answer: C

Myasthenia gravis is a form of muscle paralysis in which

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.






Answer: B

Compared to oxidative skeletal muscle fibers, those classified as glycolytic typically have

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.






Answer: E

The contraction of skeletal muscles is based on

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 then flexing.
E) myosin cross-bridges binding to actin and then flexing.







Answer: E

The olfactory bulbs are located

The olfactory bulbs are located 

A) in the nasal cavity.
B) in the anterior pituitary gland.
C) in the posterior pituitary gland.
D) in the brain.
E) in the brainstem.








Answer: D

A ligand for the umami receptor in the sense of taste is

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.






Answer: E

An injury to the occipital lobe will likely impair function of the

An injury to the occipital lobe will likely impair function of the 

A) primary visual cortex.
B) thalamus.
C) optic chiasma.
D) sense of taste.
E) sense of touch.






Answer: A

The blind spot in the human retina is the location that has the collected axons of

The blind spot in the human retina is the location that has the collected axons of 

A) ganglion cells.
B) bipolar cells.
C) primary visual cortex.
D) optic chiasma.
E) lateral geniculate nuclei.






Answer: A

Receptor proteins for the neurotransmitter molecules released by rods and cones are found on

Receptor proteins for the neurotransmitter molecules released by rods and cones are found on 

A) ganglion cells.
B) horizontal cells.
C) amacrine cells.
D) bipolar cells.
E) lateral cells.







Answer: D

In the human retina

In the human retina 

A) cone cells can detect color, but rod cells cannot.
B) cone cells are more sensitive than rod cells to light.
C) cone cells, but not rod cells, have a visual pigment.
D) rod cells are most highly concentrated in the center of the retina.
E) rod cells require higher illumination for stimulation than do cone cells.







Answer: A

For the processing of visual information in the central nervous system of humans, the neuronal projections of ganglion cells to the left and right lateral geniculate nuclei (LGN) are

For the processing of visual information in the central nervous system of humans, the neuronal projections of ganglion cells to the left and right lateral geniculate nuclei (LGN) are 

A) all ipsilateral, meaning that left eye projections stay on the left side of the brain, and vice versa.
B) all contralateral, meaning that left eye projections project to the right side of the brain, and vice versa.
C) ipsilateral for the temporal side of each retina, and contralateral for the nasal side of each retina.
D) ipsilateral for the nasal side of each retina, and contralateral for the temporal side of each retina.
E) randomly crossed in terms of which side of the retina projects to either the left or right side of the brain.






Answer: C

Lateral inhibition via amacrine cells in the mammalian retina

Lateral inhibition via amacrine cells in the mammalian retina 

A) underlies habituation of vision.
B) enhances visual contrast.
C) prevents bleaching in bright light.
D) is required for color vision to occur.
E) recycles neurotransmitter molecules.







Answer: B

A rod exposed to light will

A rod exposed to light will 

A) fire action potentials that will increase its release of glutamate.
B) undergo a graded depolarization that will increase its release of glutamate.
C) undergo a graded hyperpolarization that will increase its release of glutamate.
D) undergo a graded depolarization that will decrease its release of glutamate.
E) undergo a graded hyperpolarization that will decrease its release of glutamate.





Answer: E

Rods exposed to light will

Rods exposed to light will 

A) depolarize due to the opening of sodium channels.
B) hyperpolarize due to the closing of sodium channels.
C) depolarize due to the opening of potassium channels.
D) hyperpolarize due to the closing of potassium channels.
E) fire one action potential for each photon received.







Answer: B

Sensory transduction of light/dark information in the vertebrate retina is accomplished by

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.



Answer: E

Compared to viewing a distant object, viewing an object held within 5 cm of the eye requires a lens that

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.






Answer: B

It can be very difficult to select an angle for sneaking up to a grasshopper to catch it because grasshoppers have

It can be very difficult to select an angle for sneaking up to a grasshopper to catch it because grasshoppers have 

A) excellent hearing for detecting predators.
B) compound eyes with multiple ommatidia.
C) eyes with multiple fovea.
D) a camera-like eye with multiple fovea.
E) binocular vision.





Answer: B

Proteins coded by a very large family of related genes are active in the sensory transduction of

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.





Answer: B

The ratio of expressed receptor types to taste cells is

The ratio of expressed receptor types to taste cells is 

A) ~10:1
B) ~100:1
C) ~1,000:1
D) 1:1
E) 1:~100






Answer: D

Umami perception follows the oral presence of

Umami perception follows the oral presence of 

A) sugar water.
B) a rich chocolate flavor.
C) a savory and complex cheese.
D) acidic orange juice.
E) salt water.







Answer: C

Most of the chemosensory neurons arising in the nasal cavity have axonal projections that terminate in the

Most of the chemosensory neurons arising in the nasal cavity have axonal projections that terminate in the 

A) gustatory complex.
B) anterior hypothalamus.
C) olfactory bulb.
D) occipital lobe.
E) posterior pituitary gland.





Answer: C

Sensillae are

Sensillae are 

A) smell receptors in animals with hydrostatic skeletons.
B) mechanoreceptors that help birds remain oriented during flight.
C) a specific type of hair cell in the human ear.
D) insect taste receptors found on feet and mouthparts.
E) olfactory hairs located on insect antennae.






Answer: D

Tastes and smells are similar in that

Tastes and smells are similar in that 

A) both types of stimuli are present in thousands of different chemicals.
B) both types of stimuli must be dissolved in a body fluid before they can be detected.
C) both types of stimuli are proteins (that is, molecules of very large size and high molecular weight).
D) both types of stimuli evoke action potentials in the cells to which they bind.
E) any given stimulus for one system evokes a response from the other system.






Answer: B

The generation of action potentials in olfactory neurons initiated by odors drawn in the nasal cavity is an example of

The generation of action potentials in olfactory neurons initiated by odors drawn in the nasal cavity is an example of

A) perception.
B) sensory transduction.
C) sensory adaptation.
D) habituation.
E) lateral inhibition.




Answer: B

The lateral line system in fish transduces sensory information in a manner that, among these choices, is most similar to

The lateral line system in fish transduces sensory information in a manner that, among these choices, is most similar to 

A) human vision.
B) human olfaction.
C) human gustation.
D) human vestibular sense.
E) human thermoreception.





Answer: D

Mechanoreceptors that react to low frequency waves are part of the

Mechanoreceptors that react to low frequency waves are part of the 

A) human sense of taste.
B) pain receptors in birds.
C) human sense of smell.
D) lateral line systems in fish.
E) eyes in arthropods.






Answer: D

The sand grains or other dense materials resting on mechanoreceptors used by most invertebrates to sense gravity are called

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.






Answer: A

The perceived pitch of a sound depends on

The perceived pitch of a sound depends on 

A) which part of the tympanic membrane is being vibrated by sound waves.
B) which part of the oval window produces waves in the cochlear fluid.
C) which region of the basilar membrane was set in motion.
D) whether or not the sound moves the incus, malleus, and stapes.
E) the listener having had training in music.





Answer: C

Dizziness is a perceived sensation that can occur when

Dizziness is a perceived sensation that can occur when

A) the hair cells in the cochlea move more than their normal limits.
B) moving fluid in the semicircular canals encounters a stationary cupula.
C) rods and cones provide information that does not correspond with information received by cochlear hair cells.
D) the basilar membrane makes physical contact with the tectorial membrane.
E) the utricle is horizontal but the saccule is vertical.






Answer: B

The cochlea is an organ of auditory transduction that contains

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.





Answer: A