Question 1

A person able to hear only low-frequency sounds would probably have which of the following structural problems in the ear?

Accepted Answer

A)  The tympanum is damaged because of chronic ear infections. 
B)  The basilar membrane is stiffened along its entire length. 
C)  The ear ossicles are abnormally thickened. 
D)  There is a loss of hair cell function in the area closest to the oval window. 
A)  The tympanum is damaged because of chronic ear infections. 
B)  The basilar membrane is stiffened along its entire length. 
C)  The ear ossicles are abnormally thickened. 
D)  There is a loss of hair cell function in the area closest to the oval window. D

Question 2

Which sensory distinction is not encoded by a difference in neuron identity?

Accepted Answer

A)  white and red 
B)  red and green 
C)  loud and faint 
D)  salty and sweet 
A)  white and red 
B)  red and green 
C)  loud and faint 
D)  salty and sweet C

Question 3

Methyl jasmonate is a plant-derived compound that blocks mosquito carbon dioxide receptors. What would you expect to happen if you applied this compound to your skin and then exposed yourself to a swarm of mosquitos?

Accepted Answer

A)  The mosquitos would be repelled and fly as far away as possible from you. 
B)  The mosquitos would lack an important piece of sensory information for finding a host, and so would be less likely to bite you. 
C)  You would be a more attractive host for the mosquitos. 
D)  There would be no difference in the behavior of the mosquitos; they rely on visual cues to find their hosts. 
A)  The mosquitos would be repelled and fly as far away as possible from you. 
B)  The mosquitos would lack an important piece of sensory information for finding a host, and so would be less likely to bite you. 
C)  You would be a more attractive host for the mosquitos. 
D)  There would be no difference in the behavior of the mosquitos; they rely on visual cues to find their hosts. B

Question 4

Artificial electrical stimulation of a human's capsaicin-sensitive neurons would likely produce the sensation of ________.

Accepted Answer

A)  cold temperature 
B)  hot temperature 
C)  tactile stimulus 
D)  deep pressure 
A)  cold temperature 
B)  hot temperature 
C)  tactile stimulus 
D)  deep pressure

Question 5

Two students studying physiology taste a known "bitter" substance, and both report sensing bitterness. They then sample another substance. Student A reports sensing both a bitter taste and a salty taste, but student B reports only a salty taste. What is the most logical explanation?

Accepted Answer

A)  Student A had an allergic reaction to the food, causing him to perceive the food as being bitter. 
B)  Student A has normal "bitter" taste buds; student B has defective "bitter" taste buds that result in lower sensitivity to bitterness. 
C)  Student A has a protein receptor capable of detecting a bitter molecule found in that substance, whereas student B lacks that particular protein receptor. 
D)  Student A has normal saliva, whereas student B's saliva is more alkaline than normal. 
A)  Student A had an allergic reaction to the food, causing him to perceive the food as being bitter. 
B)  Student A has normal "bitter" taste buds; student B has defective "bitter" taste buds that result in lower sensitivity to bitterness. 
C)  Student A has a protein receptor capable of detecting a bitter molecule found in that substance, whereas student B lacks that particular protein receptor. 
D)  Student A has normal saliva, whereas student B's saliva is more alkaline than normal.

Question 6

Use the following information to answer the question.
"Marine cone snails from the genus Conus are estimated to consist of up to 700 species. These predatory molluscs have devised an efficient venom apparatus that allows them to successfully capture polychaete worms, other molluscs, or in some cases fish as their primary food sources. ?. . . conotoxins from Australian species of Conus . . . have the capacity to inhibit specifically the nicotinic acetylcholine receptors in higher animals." (B. G. Livett, K. R. Gayler, and Z. Khalil. 2004. Drugs from the sea: Conopeptides as potential therapeutics. Current Medicinal Chemistry 11:1715-23.)
What is the adaptive value of this toxin?
I.It would cause muscle spasms in the prey.
II.It would result in paralysis of the skeletal muscle of the prey.
III.It would stimulate digestive tract smooth muscle to cause nausea and vomiting of the prey.

Accepted Answer

A)  only I 
B)  only II 
C)  only III 
D)  only I and II 
A)  only I 
B)  only II 
C)  only III 
D)  only I and II

Question 7

Myasthenia gravis is a form of muscle paralysis in which ________.

Accepted Answer

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)  troponin molecules become unable to bind calcium ions 
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)  troponin molecules become unable to bind calcium ions

Question 8

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

Accepted Answer

A)  ATP needed to break actin-myosin bonds 
B)  calcium ions needed to bind to troponin 
C)  oxygen supplies needed for myoglobin 
D)  sodium ions needed to fire action potentials 
A)  ATP needed to break actin-myosin bonds 
B)  calcium ions needed to bind to troponin 
C)  oxygen supplies needed for myoglobin 
D)  sodium ions needed to fire action potentials

Question 9

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.

Accepted Answer

A)  1 → 2 → 3 → 4 → 5 
B)  2 → 1 → 3 → 5 → 4 
C)  2 → 3 → 4 → 1 → 5 
D)  5 → 3 → 2 → 1 → 4 
A)  1 → 2 → 3 → 4 → 5 
B)  2 → 1 → 3 → 5 → 4 
C)  2 → 3 → 4 → 1 → 5 
D)  5 → 3 → 2 → 1 → 4

Question 10

The transduction of sound waves into action potentials occurs

Accepted Answer

A)  in the tectorial membrane as it is stimulated by hair cells. 
B)  when hair cells are bent against the tectorial membrane, causing them to depolarize and release neurotransmitter that stimulates sensory neurons. 
C)  as the basilar membrane vibrates at different frequencies in response to the varying volume of sounds. 
D)  within the middle ear as the vibrations are amplified by the malleus, incus, and stapes. 
A)  in the tectorial membrane as it is stimulated by hair cells. 
B)  when hair cells are bent against the tectorial membrane, causing them to depolarize and release neurotransmitter that stimulates sensory neurons. 
C)  as the basilar membrane vibrates at different frequencies in response to the varying volume of sounds. 
D)  within the middle ear as the vibrations are amplified by the malleus, incus, and stapes.

Question 11

The venom of cobras contains a mixture of substances that have a variety of physiological effects. One substance in the venom works by preventing acetylcholine from binding to muscle receptors. How does the venom affect the prey of the cobra?

Accepted Answer

A)  Action potentials would be continuously generated, causing convulsive muscle contractions. 
B)  Muscle contractions would be prevented, causing paralysis. 
C)  Muscle contractions could still occur, but relaxation of the muscle would be impaired. 
D)  Action potentials would be continuously generated, causing convulsive muscle contractions; muscle contractions would then be prevented, causing paralysis. 
A)  Action potentials would be continuously generated, causing convulsive muscle contractions. 
B)  Muscle contractions would be prevented, causing paralysis. 
C)  Muscle contractions could still occur, but relaxation of the muscle would be impaired. 
D)  Action potentials would be continuously generated, causing convulsive muscle contractions; muscle contractions would then be prevented, causing paralysis.

Question 12

The motor unit in vertebrate skeletal muscle refers to ________.

Accepted Answer

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 
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

Question 13

Elephants hear sounds that are too low for humans to hear. This sensitivity is primarily due to the differences in the ________.

Accepted Answer

A)  arrangement and shape of the ossicles 
B)  flexibility of the basilar membrane in the cochlea 
C)  size and flexibility of the tympanic membrane (eardrum) 
D)  size and shape of the outer ear 
A)  arrangement and shape of the ossicles 
B)  flexibility of the basilar membrane in the cochlea 
C)  size and flexibility of the tympanic membrane (eardrum) 
D)  size and shape of the outer ear

Question 14

Which of the following sensory receptors is correctly paired with its category?

Accepted Answer

A)  hair cell-mechanoreceptor 
B)  muscle spindle-electromagnetic receptor 
C)  taste receptor-mechanoreceptor 
D)  rod-chemoreceptor 
A)  hair cell-mechanoreceptor 
B)  muscle spindle-electromagnetic receptor 
C)  taste receptor-mechanoreceptor 
D)  rod-chemoreceptor

Question 15

The round window ________.
I.dampens fluid vibrations
II.collects sound pressure waves
III.detects the frequency of sounds

Accepted Answer

A)  only I 
B)  only II 
C)  only III 
D)  only II and III 
A)  only I 
B)  only II 
C)  only III 
D)  only II and III

Question 16

When an action potential from a motor neuron arrives at the neuromuscular junction (NMJ), a series of events occurs that leads to muscle contraction. Which of the following events will occur last (that is, after all of the others listed below)?

Accepted Answer

A)  acetylcholine (ACh) release 
B)  conformational change in troponin 
C)  depolarization of the muscle cell 
D)  release of Ca²⁺ from the sarcoplasmic reticulum 
A)  acetylcholine (ACh) release 
B)  conformational change in troponin 
C)  depolarization of the muscle cell 
D)  release of Ca²⁺ from the sarcoplasmic reticulum

Question 17

The leg muscles of a sprinter would differ from a marathon runner in that ________.

Accepted Answer

A)  per gram, the sprinter's muscles would have more mitochondria than the marathon runner's muscles 
B)  per gram, the marathon runner's muscles would contain more myoglobin than the sprinter's muscles 
C)  the marathon runner's muscles would have a greater rate of contraction than the sprinter's muscles 
D)  per gram, the sprinter's muscles would use more oxygen than the marathon runner's muscles 
A)  per gram, the sprinter's muscles would have more mitochondria than the marathon runner's muscles 
B)  per gram, the marathon runner's muscles would contain more myoglobin than the sprinter's muscles 
C)  the marathon runner's muscles would have a greater rate of contraction than the sprinter's muscles 
D)  per gram, the sprinter's muscles would use more oxygen than the marathon runner's muscles

Question 18

Artificial electrical stimulation of a human's menthol-sensitive neurons would likely produce the sensation of ________.

Accepted Answer

A)  cold temperature 
B)  hot temperature 
C)  odor of pepper 
D)  deep pressure 
A)  cold temperature 
B)  hot temperature 
C)  odor of pepper 
D)  deep pressure

Question 19

The conversion of a stimulus into an action potential by a receptor cell is called ________.

Accepted Answer

A)  integration 
B)  transmission 
C)  transduction 
D)  amplification 
A)  integration 
B)  transmission 
C)  transduction 
D)  amplification

Question 20

The structure of the mammalian middle ear is adapted to convert ________.

Accepted Answer

A)  air pressure waves to fluid pressure waves 
B)  fluid pressure waves to air pressure waves 
C)  air pressure waves to nerve impulses 
D)  fluid pressure waves to nerve impulses 
A)  air pressure waves to fluid pressure waves 
B)  fluid pressure waves to air pressure waves 
C)  air pressure waves to nerve impulses 
D)  fluid pressure waves to nerve impulses

Exam 50: Sensory and Motor Mechanisms

A person able to hear only low-frequency sounds would probably have which of the following structural problems in the ear?

Which sensory distinction is not encoded by a difference in neuron identity?

Methyl jasmonate is a plant-derived compound that blocks mosquito carbon dioxide receptors. What would you expect to happen if you applied this compound to your skin and then exposed yourself to a swarm of mosquitos?

Artificial electrical stimulation of a human's capsaicin-sensitive neurons would likely produce the sensation of ________.

Two students studying physiology taste a known "bitter" substance, and both report sensing bitterness. They then sample another substance. Student A reports sensing both a bitter taste and a salty taste, but student B reports only a salty taste. What is the most logical explanation?

Myasthenia gravis is a form of muscle paralysis in which ________.

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 transduction of sound waves into action potentials occurs

The venom of cobras contains a mixture of substances that have a variety of physiological effects. One substance in the venom works by preventing acetylcholine from binding to muscle receptors. How does the venom affect the prey of the cobra?

The motor unit in vertebrate skeletal muscle refers to ________.

Elephants hear sounds that are too low for humans to hear. This sensitivity is primarily due to the differences in the ________.

Which of the following sensory receptors is correctly paired with its category?

The round window ________. I.dampens fluid vibrations II.collects sound pressure waves III.detects the frequency of sounds

When an action potential from a motor neuron arrives at the neuromuscular junction (NMJ), a series of events occurs that leads to muscle contraction. Which of the following events will occur last (that is, after all of the others listed below)?

The leg muscles of a sprinter would differ from a marathon runner in that ________.

Artificial electrical stimulation of a human's menthol-sensitive neurons would likely produce the sensation of ________.

The conversion of a stimulus into an action potential by a receptor cell is called ________.

The structure of the mammalian middle ear is adapted to convert ________.

Evolution, the Themes of Biology, and Scientific Inquiry

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The Structure and Function of Large Biological Molecules

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Membrane Structure and Function

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Gene Expression: From Gene to Protein

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