Deck 46: The Musculoskeletal System

Question 1

Shown below is an electron micrograph of part of a myofibril from a relaxed muscle fiber.Which of the labeled regions will NOT shorten when the muscle contracts?

A)A band
B)Sarcomere
C)H band
D)I band

Answer 1

A

Question 2

You decide to do an experiment with isolated myofibrils to explore the effects of ATP hydrolysis on myofibril function.You do this by bathing the myofibrils in a solution that contains a modified form of ATP, which cannot be split into ADP and P_i. At what step will myofibril function be arrested by using this compound instead of unmodified ATP?

A)Myosin heads will be unable to bind to the actin filaments.
B)There will be no block in the cycle, since ATP hydrolysis is not required for this process.
C)The myosin heads will remain attached to the actin filaments after the power stroke.
D)Myosin heads will bind to the actin filaments, but the power stroke will not occur and actin filaments will not slide over the myosin filaments.

Answer 2

A

Question 3

Which of the bone development lineages is incorrect?

A)white blood cell progenitors $\rightarrow$ monocytes $\rightarrow$ osteoclast
B)undifferentiated mesenchymal cells $\rightarrow$ osteocyte $\rightarrow$ osteoblast
C)undifferentiated mesenchymal cells $\rightarrow$ fibroblast $\rightarrow$ collagen
D)undifferentiated mesenchymal cells $\rightarrow$ chondroblast $\rightarrow$ chondrocyte

Answer 3

undifferentiated mesenchymal cells $\rightarrow$ osteocyte $\rightarrow$ osteoblast

Question 4

Utilizing more motor units for stronger muscle contractions is called

A)fast-twitching.
B)fatigue.
C)aerobic capacity.
D)recruitment.

Question 5

In arthropods, locomotion is accomplished by muscles that work against

A)each other.
B)the exoskeleton.
C)a hydrostatic skeleton.
D)mineralized bones.

Question 6

The use-dependent decrease in the ability of a muscle to generate force is called _____.

A)tetanus
B)aerobic fitness
C)fatigue
D)endurance

Question 7

The neurotransmitter released from the nerve terminus at the neuromuscular junction is __________.

A)troponin
B)Ca²⁺
C)tropomyosin
D)acetylcholine

Question 8

Select the incorrect statement about muscle and muscle fibers.

A)Long distance runners tend to have more slow-twitch muscle fibers than fast-twitch fibers.
B)A quick contraction and relaxation of an isolated skeletal muscle is called tetanus.
C)Fast-twitch fibers have fewer capillaries and mitochondria than slow-twitch fibers.
D)Slow-twitch muscle fibers have high concentrations of myoglobin.

Question 9

According to the figure, which one represents the muscle in an optimal condition for a strong contraction?

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

Question 10

In a stimulated muscle fiber, the calcium ions released by the sarcoplasmic reticulum bind to the protein _______.

A)myosin
B)tropomyosin
C)actin
D)troponin

Question 11

You witness a demonstration of a martial arts master breaking a large concrete block with his hand.Besides mastering the technique, what is another benefit of the repetitive practice of breaking concrete?

A)Repetitive stress on the long bones will solidify cartilage.
B)The Haversian canal system will supply more blood and strengthen the bone.
C)The repetitive stress will lead to remodeling and strengthening of the long bones.
D)The marrow cavity will solidify and strengthen the bone.

Question 12

Which of the following regarding the Haversian System is false?

A)Haversian canals may contain nerve fibers.
B)Haversian canals run parallel to the length of long bone.
C)Haversian canals are created by osteoclasts that tunnel through the bone matrix.
D)It keeps osteocytes alive.

Question 13

In the power stroke shown in panel c below, the thin filaments are pulled towards the center of the sarcomere.What is the specific sequence of events that occurs during a power stroke?

A)Release of the phosphate group -> release of ADP -> myosin head changes shape
B)Release of ADP-> release of the phosphate group -> myosin head changes shape
C)Release of ADP -> myosin head changes shape -> release of the phosphate group
D)Release of the phosphate group -> myosin head changes shape -> release of ADP

Question 14

Which of the following regarding bone growth is false?

A)Cartilage of growth plates actively grow in lengthwise direction.
B)Increase in bone thickness results from the adding of bone layers on top of the periosteum.
C)Some cartilage remains after it is replaced by bone.
D)Cartilage calcification encroaches on the cartilaginous growth plate.

Question 15

Insects such as mosquitoes and beetles can beat their wings at tremendous speeds.This can be accomplished because

A)their wing muscle contractions causes another set of muscles to stretch which in turn produces another contraction without waiting for the arrival of a nerve impulse.
B)their wing muscle contractions cause another set of muscles to relax which in turn produces another wing movement.
C)their wing muscle contractions are stimulated by the continuous nerve signal impulses which produce a continuous contraction of their wing muscles.
D)their wing muscle contractions are capable of producing more ATP which allows these insects to have much faster and sustained wing movements.

Question 16

The structure enabling depolarization to travel deep into the muscle fiber is the ______.

A)sarcomere
B)motor unit
C)T tubule
D)sarcoplasmic reticulum

Question 17

As the Baby Boomer generation ages, more and more joint replacement surgeries take place each year.Hip replacement surgery is the gold standard of all joint replacement surgeries, with many patients able to walk just a few hours after surgery and return home the very next day.In contrast, knee replacement surgery usually requires hospital stays of several days, followed by weeks to months of physical therapy.What best explains why the recovery after hip replacement surgery is so much faster than after knee replacement surgery?

A)The hip joint is more superficial and more accessible to surgeons than the knee joint.
B)The hip only moves in one direction, and recovery of one motion is easier than recovering movement in many directions.
C)The upper end of the thigh bone has less overall surface contact with the hip bone than its lower end has in the knee with bones of the lower leg.
D)The knee joint is stabilized by many more structures (many of which have to be cut) than the hip joint.

Question 18

The mammalian jaw is an example of what kind of moveable joint?

A)gliding joint
B)ball-and-socket joint
C)hinge joint
D)combination joint

Question 19

Which of the following is required to detach myosin from actin?

A)calcium
B)ATP
C)phosphate
D)troponin

Question 20

Select the incorrect statement related to sarcomere structure and function.

A)Two Z lines form the opposite borders of one sarcomere.
B)Thin filaments are not present in the H band of a sarcomere.
C)I bands consist of both thin and thick filaments.
D)Stacks of thick filaments produce dark bands, called the A band.

Question 21

Impulses conducted along the muscle fiber's transverse tubules stimulate the release of calcium ions into the cytoplasm

A)from the Z line.
B)from the actin and myosin subunits.
C)from the troponin.
D)from the sarcoplasmic reticulum.

Question 22

You have just read an advertisement for a new drug that claims people who take it can get muscular bodies without spending months lifting weights in the gym.The drug stimulates muscle growth in the same way that weight lifting does, which is to

A)stimulate existing muscle fibers to divide.
B)stimulate growth in the size of existing muscle fibers.
C)stimulate an increase in the proportion of slow-twitch muscle fibers.
D)stimulate existing muscle fibers to fuse with one another.

Question 23

A cross bridge is the binding of which two proteins?

A)actin and myosin
B)actin and troponin
C)myosin and troponin
D)collagen and troponin

Question 24

If you rub the scaled skin of a shark, it feels rough if you move your hand from tail to head but smooth if you move from head to tail.What is a major advantage of the scales being oriented this way?

A)to keep the shark afloat in the water
B)to counteract friction as the shark swims through the water
C)to better protect the shark from predators
D)to better prevent water loss from the body tissues

Question 25

Which of these muscles would you expect to have the greatest proportion of slow-twitch fibers?

A)the lateral rectus
B)chicken breast muscle
C)the soleus
D)the gastrocnemius

Question 26

In order for a muscle to contract, calcium ions released from the sarcoplasmic reticulum must bind to

A)troponin.
B)myosin.
C)tropomyosin.
D)ATP.

Question 27

What molecule contributes to the red color of slow-twitch muscle fibers?

A)myoglobin
B)ATP
C)glycogen
D)lactic acid

Question 28

The human skeleton is a typical vertebrate

A)exoskeleton.
B)hydrostatic skeleton.
C)axial skeleton only.
D)endoskeleton.

Question 29

A muscle fiber contracts by a sequence of events initiated by the binding of acetylcholine to its receptor.Which of the following is the correct sequence? I-The calcium-troponin complex pulls tropomyosin away from the myosin binding sites of actin.II-The freed-sites of actin bind to myosin to form cross bridges.III-Calcium ion binds to the troponin.

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

Question 30

Vertebrate bone does NOT ____.

A)contain blood vessels
B)contain sarcomere units
C)contain hydroxyapatite crystals
D)become remodeled with use

Question 31

What is the association between tropomyosin and troponin molecules in resting striated muscle fibers?

A)Tropomyosin holds the troponin in place on the myosin.
B)Troponin holds the tropomyosin in place on the myosin.
C)Tropomyosin holds the troponin in place on the actin.
D)Troponin holds the tropomyosin in place on the actin.

Question 32

The myofibrils consist of both thin filaments made of actin and thick filaments composed of

A)tropomyosin.
B)myosin.
C)acetylcholine.
D)troponin.

Question 33

The movement of actin and myosin fibers in a muscle contraction contains all of the following steps EXCEPT

A)the myosin head attaches to the actin filament.
B)the globular myosin head detaches from the actin filament.
C)myosin rolls up from one end, forming a ball.
D)the myosin head returns to its original conformation.

Question 34

All of the following statements about exoskeletons are correct EXCEPT

A)exoskeletons are made of chitin.
B)muscles are attached to the exoskeleton.
C)exoskeletons do not limit growth because they can stretch.
D)exoskeletons are shed by many arthropods in a process called molting.

Question 35

You are investigating the scene of a hit and run where somebody's pet dog was killed.It is a very hot day so the dog's body temperature is unlikely to yield any important information regarding the time of death.The dog's limbs are movable and there is no significant smell of rotting flesh.What is the best guess of the time of death?

A)within the last 10 minutes
B)within the last 2 hours
C)3-4 hours ago
D)24 hours ago

Question 36

A lab technician is preparing to dispose of a rat and a frog that were euthanized earlier in the day for a scientific study.Although the two animals died at the same time, the rat has rigor mortis while the frog does not yet show any signs of it.What is the best explanation for this time difference in the onset of rigor mortis?

A)The rat has higher concentrations of myoglobin in its muscles than the frog.
B)All the frog's muscles are fast-twitch muscles.
C)The rat's muscles have a greater density of myofilaments than the frog's muscles.
D)The frog has lower concentrations of glycogen in its muscles than the rat.

Question 37

In order for an earthworm to lengthen several contiguous segments of its body, it must

A)contract its longitudinal muscles, which pulls up the chaetae and moves the body fluid perpendicular to the long axis of the worm.
B)contract its longitudinal muscles, which extends the chaetae into the surrounding soil and moves the body fluid parallel to the long axis of the worm.
C)contract its circular muscles, which extends the chaetae into the surrounding soil and moves the body fluid parallel to the long axis of the worm.
D)contract its circular muscles, which pulls up the chaetae and moves the body fluid parallel to the long axis of the worm.

Question 38

Which of the following is/are required with actin and myosin in order to initiate muscle contraction?

A)ATP
B)calcium and phosphate
C)phosphate
D)calcium and ATP

Question 39

The muscles that move the eye have a high proportion of fast-twitch fibers and reach maximum tension very fast.These fibers belong to the class of __________ fibers.

A)type I
B)type II
C)type III
D)type IV

Question 40

Impulses conducted along the transverse tubules of the muscle fiber stimulate

A)the release of ATP.
B)the binding of actin to the Z lines.
C)tropomyosin and troponin binding.
D)the release of calcium ions.

Question 41

Imagine an earthworm that has no chaetae.How would the lack of chaetae affect movement of the earthworm?

A)The earthworm would have difficulty changing locations, since it cannot anchor itself in the soil.
B)The earthworm would be much flatter than normal since it has no hydrostatic skeleton.
C)The earthworm would only be able to extend its body segments.
D)The earthworm would only be able to shorten its body segments.

Question 42

The masseter muscles originate on your cheekbones and insert into the posterior corners of the mandible (the lower jaw bone) underneath your ears.Will contraction of the masseter muscles open or close your jaw?

A)open
B)close

Question 43

Sarin gas is an inhibitor of an enzyme that functions in the neuromuscular junction to break down acetylcholine.What is the most likely description of how a person would die after inhaling this poisonous gas?

A)suffocation via paralysis, or a block in stimulation, of the respiratory muscles
B)epileptic convulsions caused by disorganized electrical activity in the brain
C)by a heart attack
D)suffocation via tetanus, or constant stimulation, of the respiratory muscles

Question 44

The figure below represents a joint in the hind leg of a grasshopper.The exoskeleton of the leg is indicated by the two pairs of parallel black lines.A muscle that moves this leg is fixed to the skeleton at the end marked with a blue star.When the muscle contracts, it will pull on the tendon at its opposite end.Which configuration shows the most likely arrangement of the exoskeleton and a muscle that increases the flexion of this leg?

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

Question 45

Based on the above diagram and other information from your text, what is the most likely (e.g., most parsimonious) explanation for the evolution of flight in vertebrates?

A)The common ancestor of all terrestrial vertebrates was wingless and wings evolved independently three different times: in bats, in pterosaurs and in the common ancestor of birds and dinosaurs.
B)Wings evolved once in vertebrates (e.g., the common ancestor of all terrestrial vertebrates had wings) and wings were subsequently lost in all but three lineages: bats, pterosaurs and birds.
C)The common ancestor of all terrestrial vertebrates was wingless and wings evolved independently three different times: in bats, in pterosaurs and in birds.
D)The common ancestor of all terrestrial vertebrates was wingless and wings evolved independently two different times: once in bats and once in the common ancestor of birds, pterosaurs and dinosaurs.