48) Which of the following statements regarding exercise is true?
A) The main source of energy during aerobic exercise is ATP from aerobic respiration.
B) For an activity such as jogging or long-distance running, the primary source of energy is
stored ATP and PCr.
C) During a short burst of activity such as a sprint, the main source of energy is aerobic
respiration.
D) If the demand for ATP outstrips oxygen supply, muscles switch to aerobic fermentation.
49) Muscles that are constantly active, such as those maintaining our body posture, have a high
proportion of
A) fast, fatigue-resistant fibers.
B) fast, fatigue-susceptible fibers.
C) slow, fatigue-resistant fibers.
D) slow, fatigue-susceptible fibers.
50) A tennis player serving the ball uses fast muscle fibers. The ATP needed to accomplish this
comes from
A) anaerobic fermentation.
B) aerobic respiration.
C) conversion of lactic acid to ATP.
D) conversion of Ca2+ to ATP.
51) A muscle fiber from the latissimus dorsi (one of the back muscles) of a chimpanzee has a lot
of mitochondria and myoglobin and can generate relatively little force. Which type of muscle
fiber is being described?
A) a fast, fatigue-resistant fiber
B) a fast, fatigue-susceptible fiber
C) a slow, fatigue-resistant fiber
D) a slow, fatigue-susceptible fiber
52) Mutations in the gene for troponin can result in the production of the troponin protein, which
has varying affinities for Ca2+ ions. Suppose that in a muscle cell a mutant troponin is expressed
that has such a high affinity for Ca2+ ions that once they bind to troponin they cannot unbind.
What will likely happen in this muscle cell?
A) Myosin heads will not bind to actin after action potentials stop being received.
B) Myosin heads will bind to actin after action potentials stop being received.
C) Tropomyosin will not move to expose myosin binding sites.
D) Cross-bridges will form between myosin and tropomyosin.
53) Acetylcholine (ACh) is released by motor neurons and binds to receptors on muscle cells to
initiate action potentials. Some snake venom contains specific toxins that bind irreversibly to
these receptors and block acetylcholine’s ability to bind. If an animal is bitten by a snake with
these toxins in its venom, what do you predict would happen?
A) The animal’s muscles would not use stored ATP for energy.
B) The animal’s muscles would contract uncontrollably.
C) The animal’s muscles would not be able to contract.
D) The animal’s muscles would use lactic acid fermentation for energy.
54) Fast muscle fibers contain a high proportion of myofibrils, which allows the fibers to
generate high amounts of force. However, this leaves little room in the fibers for other cellular
components, including mitochondria. The opposite is true for slow muscle fibers. Does this
information support or refute what you know about the fatigue-susceptibility of fast and slow
fibers? Why or why not?
A) It supports it because if fast fibers have less room for mitochondria than slow fibers do, they
cannot produce as much ATP and thus are less fatigue-resistant than slow fibers.
B) It supports it because if fast fibers have less room for mitochondria than slow fibers do, they
can produce more ATP than slow fibers and thus are more fatigue-resistant than slow fibers.
C) It refutes it because if fast fibers have less room for mitochondria than slow fibers do, they
can produce more ATP than slow fibers and thus are less fatigue-resistant than slow fibers.
D) It refutes it because if fast fibers have less room for mitochondria than slow fibers do, they
cannot produce as much ATP and thus are more fatigue-resistant than slow fibers.
55) Your friend is complaining of middle back pain. She also says that she hurts the most near
her spine. What part of her back may have been injured?
A) cervical vertebrae
B) sacral vertebrae
C) lumbar vertebrae
D) thoracic vertebrae
30.2 Art Questions
1) Which part of this figure depicts the thoracic vertebrae?
A) part A
B) part B
C) part C
D) part D
2) Which part of this figure depicting a bone shows spongy bone tissue?
A) part A
B) part B
C) part C
D) part D
3) Which of the following treatments could possibly help to transform the bone on the right to
the bone on the left?
A) wearing long sleeves while out in the sun
B) swimming for 30 minutes a day
C) removing calcium from the diet
D) taking vitamin D supplements
4) An animal’s locomotor muscle was dissected and the percentages of fast and slow fibers were
determined and plotted in the figure below. Which of the following muscles is the likely source
for this data?
A) flight muscles of a migratory bird
B) thigh muscles of a marathon runner
C) neck muscles of a chimpanzee
D) jumping muscles of a frog
30.3 Scenario Questions
After reading the paragraphs below, answer the questions that follow.
Rickets is a softening of the bones that can lead to frequent fractures and skeletal deformities.
The legs of a person with rickets tend to bow outward under the force exerted by body weight
and movement. British scientists recently found a serious increase in the incidence of rickets and
other bone deficiencies among women in Middle Eastern countries who cover their bodies
completely to express a form of religious belief, as well as among their breast-fed children.
Most of the body’s vitamin D, which is necessary for calcium absorption by bone tissue, is
obtained through sunlight acting on the skin. Doctors warn that women who completely cover
their skin do not get enough sunlight to produce the vitamin D necessary for bone health. This
lack of sun exposure also lowers the level of vitamin D in their breast milk, which means that
their children may develop the same vitamin D deficiencies. Lack of calcium and phosphorous,
which are needed for bone repair and replacement, can also lead to rickets. Rickets caused by a
dietary lack of these minerals is more common in developing countries because dairy products
and green vegetables, the best sources of calcium, are not commonly eaten.
1) As a physician caring for a nursing woman who has chosen to dress in a way that covers her
skin but who is concerned about rickets developing in her baby, you might advise her to
A) exercise more.
B) eats lots of meat and potatoes.
C) take vitamin D and calcium supplements.
D) give up smoking.
2) In rickets, lack of calcium decreases the strength of the mineral matrix of compact bone so
that it is unable to
A) resist compression.
B) complete extension.
C) complement muscle contraction.
D) bend at the joints.
After reading the paragraph below, answer the questions that follow.
The “Ironman” is a version of the triathlon, a race that includes three events: swimming,
bicycling, and running. In an Ironman, an athlete must swim 2.4 miles, bike 112 miles, and run
26.2 miles, in that order, without a break. The annual Ironman World Championship is held in
Hawaii every year. The men’s course record was set in 2011 by Australia’s Craig Alexander with
a time of 8 hours, 18 minutes, and 37 seconds, and the women’s course record was set in 2009 by
England’s Chrissie Wellington with a time of 8 hours, 54 minutes, and 2 seconds.
3) What type of muscle fibers would likely be found in the legs of athletes who attempt to
complete this race?
A) fast, fatigue-resistant fibers
B) fast, fatigue-susceptible fibers
C) slow, fatigue-resistant fibers
D) slow, fatigue-susceptible fibers
4) What type of energy would the leg muscles of athletes that enter this race use during the final
26.2-mile foot race?
A) stored ATP and PCr
B) aerobic respiration
C) stored ATP and PCr plus lactic acid fermentation
D) lactic acid fermentation
5) Which event of the Ironman would likely contribute the most to bone development and
growth?
A) swimming
B) bicycling
C) running
D) All events would contribute equally.
After reading the paragraph below, answer the questions that follow.
When sarcomeres contract, they generate force (tension). However, the amount of force
generated depends on the sarcomere length and the amount of thick and thin filament overlap.
Below is a figure that details the force—generating properties of a single sarcomere. This figure
was modified from a scientific paper by Al Gordon and colleagues from 1966 and is a classic
illustration of the relationship between sarcomere length and force.
6) At what point on the graph is the sarcomere the most extended?
A) point A
B) point B
C) point C
D) point E
7) At what point on the graph is the most tension generated?
A) point A
B) point B
C) point C
D) point E
8) At what point on the graph are thick and thin filaments most overlapped?
A) point A
B) point B
C) point D
D) point E
9) What portion of the graph would involve myosin forming cross-bridges and going through
power strokes?
A) from A to B
B) from D to B
C) from B to E
D) from A to E
10) Mammalian muscles can shorten approximately 35% of their resting length when all
sarcomeres contract. If a sarcomere passes through maximal tension generation during this 35%
contraction, what is the likely starting point for contraction of a sarcomere?
A) point A
B) point B
C) point D
D) point E