chapter 14

Question 1

Which of the following statements is correct with respect to flagella and cilia?
A) The flagellum is usually at the leading end of a swimming sperm cell.
B) Cilia generate a force parallel to the cell surface.
C) There usually are fewer cilia than flagella.
D) Cilia generally are longer than flagella.
E) Cilia often have a helical pattern of movement.

Answer 1

B

Question 2

The axonemal “9 + 2” pattern of microtubules is nine ________ surrounding a(n) ________.
A) outer doublets; central pair
B) basal bodies; inner two
C) central tubules; double pair
D) B tubule structures; middle two
E) triplet microtubules; basal bodies

Answer 2

A

Question 3

The “9 + 0” pattern of microtubules is associated with
A) bacterial locomotion.
B) cyanobacterial locomotion.
C) respiratory tract cilia.
D) sperm tail flagella.
E) primary (sensory) cilia.

Answer 3

E

Question 4

Which of the following lists of structures is in the correct order from inside to outside of the
cell?
A) Axoneme, transition zone, basal body
B) Transition zone, basal body, axoneme
C) Axoneme, basal body, transition zone
D) Basal body, transition zone, axoneme
E) Basal body, axoneme, transition zone

Answer 4

D

Question 5

In the axoneme, dynein sidearms are anchored on
A) B tubules.
B) A tubules.
C) central pair tubules.
D) radial spokes.
E) interdoublet nexin.

Answer 5

B

Question 6

Each of the following diseases is classified as a primary cilia dysplasia (also known as a
ciliopathy) except
A) Kartagener’s syndrome.
B) situs inversus totalis.
C) heterotaxia.
D) Griscelli’s disease.
E) All are primary cilia dysplasias.

Answer 6

D

Question 7

________ links the thick filaments to the Z line.
A) Troponin
B) Tropomyosin
C) Titin
D) Nebulin
E) Myomesin

Answer 7

C

Question 8

Striated muscle has light and dark bands. The light bands are called ________, whereas the
dark bands are called ________.
A) Z lines; M lines
B) H zones; M zones
C) A bands; I bands
D) I bands; A bands
E) M lines; A bands

Answer 8

D

Question 9

Cytological examination of resting and contracted muscle provides important support for the
sliding filaments model for how skeletal muscle contracts. This evidence includes the
observation that during contraction the
A) Z lines move farther apart.
B) lengths of the thick filaments shorten significantly.
C) lengths of the thin filaments shorten significantly.
D) I bands get longer.
E) H zone becomes narrower.

Answer 9

E

Question 10

Biochemical evidence supporting the sliding filament model of muscle contraction includes
the observation that
A) myosin light chains can be phosphorylated.
B) titin connects each end of a thick filament to a Z line.
C) TnC binds Ca2+.
D) actin has polymerization ATPase activity.
E) myosin has an ATP-dependent cross-bridge cycle.

Answer 10

E

Question 11

Which of the following major protein components of skeletal muscle is incorrectly matched
with its function?
A) Titin–links thick filaments to Z line
B) Nebulin–links thin filaments to Z line
C) Myomesin–links myosin filaments at M line
D) Troponin–binds along the length of the thin filaments and blocks myosin binding sites
E) Actin–major component of thin filaments

Answer 11

D

Question 12

Motility may involve
A) movement of a cell/organism through its environment.
B) movement of the environment past a cell.
C) movement of components within a cell.
D) shortening of a cell.
E) All of the above are correct.

Answer 12

E

Question 13

Which of the following changes take place as the muscle contracts?
A) The Z lines get closer together.
B) The H zones get smaller.
C) The I band gets smaller.
D) The A band gets smaller.
E) A, B, and C are correct.

Answer 13

E

Question 14

In relaxed muscle, Ca2+ is found in highest concentration in the
A) sarcoplasm.
B) T tubules.
C) sarcoplasmic reticulum.
D) sarcolemma.
E) neuromuscular junction.

Answer 14

C

Question 15

All of the following are actin-dependent nonmuscle motilities except
A) extension of the ER.
B) cleavage furrow constriction in cytokinesis.
C) chemotaxis.
D) cyclosis or cytoplasmic streaming.
E) amoeboid movement.

Answer 15

A

Question 16

Which of the following characteristics is not associated with cardiac muscle?
A) Intercalated discs
B) Electrical coupling by gap junctions
C) Involuntary nervous control
D) Fusion of cardiomyocytes into large multinucleated myofibers
E) Striations

Answer 16

D

Question 17

Ca2+-calmodulin stimulates phosphorylation of myosin by
A) Ca2+-ATPase.
B) focal adhesion kinase.
C) myosin light chain kinase.
D) ryanodine receptor.
E) titin.

Answer 17

C

Question 18

Which of the following is incorrect about stimulation of striated muscle contraction by the
neuromuscular junction?
A) Acetylcholine is stored in vesicles in the axon terminal.
B) Acetylcholine is secreted in response to a nerve action potential.
C) Acetylcholine binds to soluble receptors in the extracellular environment.
D) Acetylcholine binding stimulates sodium ions to enter the muscle cell.
E) T tubules carry action potentials into the muscle cell.

Answer 18

C

Question 19

Motor proteins convert
A) mechanical energy to chemical energy.
B) heat energy to mechanical energy.
C) kinetic energy to mechanical energy.
D) chemical energy to mechanical energy.
E) chemical energy to heat energy.

Answer 19

D

Question 20

Which of the following features is not shared by microtubule and microfilament molecular
motors?
A) Coupling ATP hydrolysis to change shape and attachment of the motor to its associated
cytoskeletal filament
B) Retention of bound ADP and Pi products immediately after ATP hydrolysis
C) Cycles of ATP hydrolysis, release of ADP and Pi, and binding of new ATP as they undergo a
cross-bridge cycle of force production on a filament
D) Similar structural features that transduce changes in the motor protein shape into movement
E) The motors share all these features.

Answer 20

E

Question 21

Arp2/3-dependent actin polymerization directly drives which of the following activities at
the leading edge of crawling cells?
A) Filament rearward translocation
B) Lamellipodia protrusion
C) New adhesion formation
D) Generation of tension
E) Focal adhesion detachment

Answer 21

B

Question 22

Where would you expect to find the Ca2+-activated form of gelsolin in cells crawling by
amoeboid movement?
A) In and around focal adhesions
B) At the intercalated discs
C) At a pseudopodium
D) In the primary cilium
E) At the cell trailing edge where force is produced to drive endoplasm forward streaming.

Answer 22

C

Question 23

Which of the following is the correct order of events in a crawling cell?
A) Protrusion at the cell’s leading edge, attachment of protrusion, pulling the cell forward,
release, and retraction of trailing edge
B) Attachment of protrusion, pulling the cell forward, protrusion at the cell’s leading edge,
release, and retraction of trailing edge
C) Release and retraction of protrusion, protrusion at the cell’s leading edge, attachment of
trailing edge, pulling the cell forward
D) Attachment of protrusion, protrusion at the cell’s leading edge, pulling the cell forward,
release, and retraction of trailing edge
E) Pulling the cell forward, release and retraction of protrusion, protrusion at the cell’s leading
edge, attachment of trailing edge.

Answer 23

A

Question 24

During the sliding process in microtubules in cilia and flagella, the stalks of an axonemal
dynein attach to, produce force on, and detach from a(n) ________ in a cyclic manner.
A) A tubule
B) B tubule
C) radial spoke
D) interdoublet nexin connections
E) central pair

Answer 24

B

Question 25

In striated muscle contraction, the Ca2+-ATPase pump A) releases Ca2+ from the T tubule. B) secretes Ca2+ from the axon terminal. C) is voltage-gated. D) decreases Ca2+ in the sarcoplasm. E) increases Ca2+ binding to TnC.

Answer 25

D

Question 26

Which of the following proteins attaches a crawling cell to the substrate in a focal adhesion? A) Actin B) Myosins C) α-actinin D) Integrin E) Titin

Answer 26

D

Question 27

Which of the following sequences is in the correct order for the cyclic process by which a myosin head generates force on an actin filament for muscle contraction? A) Power stroke, cross-bridge formation, cross-bridge dissociation, cocking of myosin head B) Cross-bridge formation, power stroke, cross-bridge dissociation, cocking of myosin head C) Cross-bridge formation, cocking of myosin head, power stroke, cross-bridge dissociation D) Cross-bridge formation, cross-bridge dissociation, cocking of myosin head, power stroke E) Cross-bridge formation, power stroke, cross-bridge dissociation, power stroke, cocking of myosin head

Answer 27

B

Question 28

Axonemal dyneins are A) associated with organelle movement. B) associated with cilia and flagella. C) monomeric myosin-like proteins. D) responsible for axonal anterograde transport. E) All of the above are correct.

Answer 28

B

Question 29

Which of the following is responsible for retrograde axonal transport? A) Cytoplasmic dynein B) Kinesin 5 C) Kinesin 13 D) Myosin V E) Kinesin 1

Answer 29

A

Question 30

In the sliding filament model of muscle contraction, I bands contain A) thick filaments. B) thin filaments. C) myosin II. D) myomesin. E) both thick and thin filaments.

Answer 30

B

Question 31

Each of the following is an example of microfilament-based motility and contractility except A) ciliary motility. B) pseudopodia formation. C) cytoplasmic streaming. D) cytokinesis. E) trailing edge retraction in a moving cell.

Answer 31

A

Question 32

Which of the following would you expect to observe in an in vitro experimental mixture containing microtubules anchored by their minus ends to centrosomes, polystyrene beads with kinesin or dynein motors attached, and ATP? A) Movement of kinesin-attached beads along microtubules away from centrosomes B) Movement of dynein-attached beads along microtubules toward from centrosomes C) Movement of beads in either direction along a single microtubule D) Removal of ATP stopping all bead movement along microtubules E) All would be expected.

Answer 32

E

Question 33

Kinesin 1 and myosin II share each of the following features except A) two heads. B) dimers formed by heavy chain tails coiled around each other. C) formation of filaments. D) plus end directed motor activity. E) ATPase activity.

Answer 33

C

Question 34

In the axoneme, sidearms A) are 10 protofilament incomplete microtubules attached to 13 protofilament microtubules. B) generate force to slide microtubules past one another. C) project toward the central pair from each outer doublet. D) link adjacent doublet microtubules to limit sliding. E) are complete 13 protofilament microtubules.

Answer 34

B

Question 35

In the axoneme, nexin A) transports tubulin to the axoneme tip for assembly. B) generates force for outer doublets sliding past each other. C) projects inward from each doublet toward the central pair microtubules. D) links adjacent outer doublets to limit sliding. E) connects each outer doublet to the plasma membrane

Answer 35

D

Question 36

Which of the following would you use to inhibit the contraction of muscle in vitro as a control for an experiment you are conducting? A) A drug that increases sarcoplasm Ca2+ concentration B) A motor protein ATPase inhibitor C) A Ca2+-ATPase inhibitor D) A drug that increases T-tubule depolarization E) All would inhibit muscle contraction.

Answer 36

B

Question 37

Kinesin 1 is highly processive motor, taking more than 100 steps (covering 1 μm along a microtubule) before dissociating, primarily because A) it hydrolyzes ATP more rapidly than other motors. B) one of its two heads is always attached in a hand-over-hand mechanism. C) light chains at its nonmotor end attach to cargo vesicles. D) its efficiency of converting ATP hydrolysis energy to useful work is 60—70%. E) All are required for processivity.

Answer 37

B

Question 38

Primary cilia have a(n) ________ function and typically display a ________ structure. A) axonal; 9+2 B) motile; 9+0 C) motile; 9+2 D) sensory; 9+0 E) filopodial; 9+4

Answer 38

D

Question 39

A Ca2+-binding protein that activates many enzymes, including myosin light-chain kinase, is A) Ca2+-ATPase. B) gelsolin. C) calmodulin. D) myosin light-chain phosphatase. E) TnC.

Answer 39

C