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Chapter 20 Quiz
Return to Animal Physiology 4e Student Resources
Chapter 20 Quiz
Quiz Content
*
not completed
.
Which statement about skeletal muscle is true?
Proteins in thick filaments pull on thin filaments, while intermediate filaments hold sarcomeres together.
correct
incorrect
Proteins in thin filaments pull on intermediate filaments, while thick filaments hold sarcomeres together.
correct
incorrect
Proteins in thin filaments pull on thick filaments, while intermediate filaments hold sarcomeres together.
correct
incorrect
Proteins in intermediate filaments pull on thin filaments, while thick filaments hold sarcomeres together.
correct
incorrect
*
not completed
.
The power stroke of the myosin head occurs in conjunction with what other event of the cross-bridge cycle?
ATP hydrolysis to ADP and inorganic phosphate
correct
incorrect
ATP binding to the myosin head
correct
incorrect
Release of ADP from the myosin head
correct
incorrect
Release of inorganic phosphate from the myosin head
correct
incorrect
*
not completed
.
In the absence of _______, a muscle can contract but cannot relax.
Ca
2+
correct
incorrect
myosin
correct
incorrect
ATP
correct
incorrect
oxygen
correct
incorrect
*
not completed
.
In a vertebrate skeletal muscle cell, depolarization of the t-tubule membrane causes dihydropyridine receptors to
open and conduct Ca
2+
into the t-tubule.
correct
incorrect
open and conduct Ca
2+
into the sarcoplasmic reticulum.
correct
incorrect
change conformation and interact with ryanodine receptors.
correct
incorrect
bind dihydropyridines and change configuration.
correct
incorrect
*
not completed
.
A hypothetical skeletal muscle cell with no t-tubules would probably
contract and relax more quickly during twitch contractions.
correct
incorrect
contract and relax more slowly during twitch contractions.
correct
incorrect
shorten more quickly during tetanic contractions.
correct
incorrect
have a lower rate of aerobic ATP production.
correct
incorrect
*
not completed
.
During an isometric tetanic contraction, the sarcomeres generate
no force.
correct
incorrect
force but cannot stretch the elastic component of the muscle.
correct
incorrect
force and stretch the elastic component of the muscle, but they cannot move the load.
correct
incorrect
force but do not transmit it to the elastic component of the muscle.
correct
incorrect
*
not completed
.
Why is the latent period of an isotonic twitch different from that of an isometric twitch?
The motoneuron sends a longer action potential if there is an isotonic load on the muscle.
correct
incorrect
The motoneuron sends a longer action potential if there is an isometric load on the muscle.
correct
incorrect
An isotonic twitch does not begin until the muscle develops enough force to lift the load.
correct
incorrect
An isometric twitch does not begin until the muscle develops enough force to lift the load.
correct
incorrect
*
not completed
.
Which of the following factors would increase the stimulation frequency at which a muscle shifts from twitch to tetanic contractions?
Voltage-gated sodium channels with faster kinetics
correct
incorrect
A larger volume fraction of mitochondria
correct
incorrect
A larger volume fraction of myofibrils
correct
incorrect
A larger number of SR Ca
2+
-ATPase proteins
correct
incorrect
*
not completed
.
On the plateau of the length–tension curve,
all myosin heads are in proximity to actin.
correct
incorrect
all actin monomers are in proximity to myosin heads.
correct
incorrect
the width of the A band is minimized.
correct
incorrect
the distance between Z disc is minimized.
correct
incorrect
*
not completed
.
If a muscle contains 10,000 sarcomeres in a series (i.e., end-to-end along its length), each sarcomere is ~2.5 µm in length, and each sarcomere can shorten by 2.5 µm/s, how fast can the muscle shorten?
2.5 µm/s
correct
incorrect
2.5 mm/s
correct
incorrect
2.5 cm/s
correct
incorrect
2.5 m/s
correct
incorrect
*
not completed
.
Muscle A has a volume of 200 cm
3
, a length of 10 cm, and a cross-sectional area of 20 cm
2
. Muscle B has a volume of 100 cm
3
, a length of 5 cm, and a cross-sectional area of 20 cm
2
. Which statement about muscles A and B is true?
Both muscles can produce the same power, but they can shorten at different speeds.
correct
incorrect
Both muscles can shorten at the same speed, but they can produce different amounts of power.
correct
incorrect
Both muscles can exert the same force and can produce the same amount of power.
correct
incorrect
Both muscles can exert the same force, but one can shorten more quickly than the other.
correct
incorrect
*
not completed
.
Order the mechanisms of ATP generation by decreasing yield per episode of use.
Creatine phosphate; anaerobic glycolysis; aerobic catabolism
correct
incorrect
Anaerobic glycolysis; creatine phosphate; aerobic catabolism
correct
incorrect
Aerobic catabolism; creatine phosphate; anaerobic glycolysis
correct
incorrect
Aerobic catabolism; anaerobic glycolysis; creatine phosphate
correct
incorrect
*
not completed
.
Which statement about slow oxidative and fast glycolytic muscle fibers is
false
?
Their thick and thin filaments are arranged differently.
correct
incorrect
They have different numbers of organelles such as mitochondria and sarcoplasmic reticulum.
correct
incorrect
They have different amounts of metabolic enzymes such as hexokinase or citrate synthase.
correct
incorrect
They have different amounts of certain excitation–contraction coupling proteins, such as SR Ca
2+
-ATPase.
correct
incorrect
*
not completed
.
Which best explains why fast glycolytic muscle fibers are larger than slow oxidative fibers?
Slow oxidative fibers rely on the diffusion of oxygen via capillaries.
correct
incorrect
Slow oxidative fibers can oxidize a variety of fuels, whereas fast glycolytic fibers primarily oxidize glucose/glycogen.
correct
incorrect
Fast glycolytic fibers are larger to generate larger action potentials and greater force.
correct
incorrect
Fast glycolytic fibers are larger to exchange glucose across the sarcolemma more quickly.
correct
incorrect
*
not completed
.
Slow oxidative fibers in skeletal muscle are used
only for motions requiring maximum power output, such as jumping.
correct
incorrect
constantly, for postural activities such as standing and sitting.
correct
incorrect
intermittently, for activities requiring more force output than the fast glycolytic fibers alone can produce.
correct
incorrect
intermittently, for activities requiring more force output than the fast glycolytic and fast oxidative glycolytic fibers alone can produce.
correct
incorrect
*
not completed
.
Compared to a typical avian leg muscle, hummingbird flight muscle
produces more force per cross-sectional area.
correct
incorrect
has an exceptionally high volume fraction of mitochondria.
correct
incorrect
has very high numbers of muscle fibers per capillary.
correct
incorrect
has very high levels of SR Ca
2+
-ATPase, but low levels of mitochondria.
correct
incorrect
*
not completed
.
Muscles of the larynx that help mammals to produce complex sounds can contract and relax at much higher frequencies than the muscles of the limbs, but they produce relatively low force as they act on the vocal cords. Based on these characteristics, one would predict that laryngeal muscles have
high levels of myosin.
correct
incorrect
high levels of parvalbumin.
correct
incorrect
high levels of troponin T.
correct
incorrect
unusually long sarcomeres.
correct
incorrect
*
not completed
.
Calcium enters the cytoplasm of a smooth muscle cell by
active transport from the sarcoplasmic reticulum only.
correct
incorrect
active transport from the extracellular space and the sarcoplasmic reticulum.
correct
incorrect
diffusion from the sarcoplasmic reticulum only.
correct
incorrect
diffusion from the extracellular space and the sarcoplasmic reticulum.
correct
incorrect
*
not completed
.
Which of the following
cannot
modulate force production in smooth muscle?
Inhibition of myosin light-chain kinase
correct
incorrect
Inhibition of myosin light-chain phosphatase
correct
incorrect
Binding of Ca
2+
to troponin C
correct
incorrect
Hormonal stimuli
correct
incorrect
*
not completed
.
In smooth muscle, calcium must bind to _______ to initiate contraction.
calmodulin
correct
incorrect
troponin C
correct
incorrect
myosin
correct
incorrect
ryanodine receptor
correct
incorrect
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