Download AnS 214 SI Multiple Choice Set 2 Week 9/28 – 10/2 The following

AnS 214 SI Multiple Choice Set 2
Week 9/28 – 10/2
The following multiple choice questions pertain to material covered in this week's lecture set. Answering the following
questions will aid your exam preparation. These questions are meant as a gauge of your content knowledge - use them to
pinpoint areas where you need more preparation.
Answers to last week's MC Set 1:
Contact me if you have questions regarding this answer key.
1. C
6. D
11. E
2. B
7. B
12. E
3. E
8. E
13. D
4. C
9. A
14. A
5. A
10. B
15. B
16. E
17. C
18. E
19. A
20. C
21. C
22. A
23. B
24. E
25. E
1. Belgian blue cattle are phenotypically 'double-muscled' because
A. They overproduce a growth factor called myostatin, causing extreme hypertrophy of muscle groups and
B. They are missing the gene, myotropin, which initiates hyperplasia, resulting in twice the number of muscle cells
C. Their muscles undergo hyperplasia due to a mutant form of the gene coding for myostatin - the protein
responsible for halting muscle growth
D. They are made to run four three-mile sprints/day, uphill both ways
E. They have a mutant form of the gene somatostatin, which produces a protein that competes for myostatin
receptors, altering growth patterns
2. Botox is a neurotoxin that prevents the release of acetylcholine, effectively paralyzing the injected muscle. It achieves
this by
A. Adhering to the post-synaptic receptors, preventing them from binding acetylcholine
B. Binding to myonuclei, causing them to overproduce acetylcholinesterase, which degrades AChE before it can
bind to receptors
C. Adhering to SNAP-25, the protein responsible for opening Ca+ channels, preventing vesicular release
D. Cleaving SNAP-5, the enzyme that degrades Ca+ vesicles, allowing them to release their content
E. Inactivates SNAP-25, the protein responsible for the release of synaptic vesicles, preventing the release of
AChE into the synaptic cleft
3. Which of the following is TRUE about motor units?
A. It consists of a myofiber and all the motor neurons that activate it
B. It is able to grow with age by recruiting de-innervated fast twitch fibers
C. Large motor units are recruited first, followed by smaller units to provide a gradient of exerted force
D. Myofibers belonging to a single motor unit are segregated to a single part of a muscle series, which is
responsible for the phenomenon of muscle groups
E. The number of functional motor units increases with age, allowing for finer object manipulation
4. Acetylcholine in muscles
A. Is the primary neurotransmitter at the NMJ, responsible for the hyperpolarization of the post synaptic
sarcolemma
B. Diffuses across the NMJ to activate Na+/K+ channels on a post-synaptic dendrite, initiating end plate potential
C. Binds to ligand-gated channels on the sarcoplasmic reticulum to release Ca+ ions
D. Binds to voltage gated channels in the junctional folds, initiating end plate potential
E. Is degraded by acetylcholinesterase to prevent continuous muscle stimulation
5. Opening of Na+/K+ channels on the sarcolemma
A. Induces depolarization of the sarcoplasmic reticulum, inducing the release of Cl- ions
B. Induces hyperpolarization of the sarcolemma, which draws positively charged Ca+ out of the SR
C. Results in a conformational shift of the voltage sensitive tubular proteins, causing Ca+ leakage to the sarcoplasm
D. Allows the opening of voltage gated Ca+ channels on the SR
E. Triggers apoptosis of the myofiber
6. Ca+ ions in the sarcoplasm
A. Bind to the TI subunit of troponin, inducing a conformational change in tropomyosin that uncovers G-actin
binding sites
B. Allows myosin to bind to actin by causing tropomyosin to slide deeper into thin filament grooves
C. Bind to tropomyosin, causing a conformational change in troponin that permits binding of myosin heads
D.Trigger a tyrosine kinase cascade the releases AChE into the synaptic cleft.
E. Destroy myostatin-acetylcholine linkages, inhibiting release of T4 from the thyroid
7. Ca+ ions are returned to the SR with the help of a protein called
A. SNAP-25
B. myostatin
C. calcitonin
D. calsequestrin
E. calmodulin
8. An increase in strength is correlated to _______________; an increase in flexibility involves ______________________
A. addition of sarcomeres in series; addition of sarcomeres in parallel
B. lean protein intake; yoga
C. higher muscle cross-section; longer sarcomere series in myofibers
D. greater overlap of actin and myosin; longer resting length of sarcomeres
E. higher affinity of SR for Ca+ ions; greater number of myofibrils per myofiber
9. Low concentration of Ca+ ions in the cell
A. hinders the attachment of myosin heads to actin binding sites
B. results in activation of cross-bridge formation
C. is a result of sarcolemma depolarization
D. suggests a dietary deficiency
E. results in a higher affinity of myosin for actin
10. Attachment of an ATP molecule to the myosin head
A. causes the myosin head to ratchet into the 'cocked' position
B. is responsible for rigor mortis
C. causes bound myosin to return to its relaxed position, resulting in actin sliding past myosin
D. allows the myosin head to attach to actin
E. allows the myosin head to detatch from actin
11. Relaxation involves all of the following EXCEPT
A. ACh degradation by AChE
B. repolarization of the sarcolemma
C. attachment of ATP to myosin
D. binding of cytoplasmic Ca+ to calsequestrin
E. passive diffusion of Ca+ into terminal cisternae
12. Excitation-contraction coupling involves
A. hyperpolarization of the sarcolemma
B. an increase in the sarcomere's actin-myosin overlap
C. sliding of acting and myosin filaments past each other
D. attachment of actin heads to myosin
E. attachment of Ca+ to troponin in order to free actin binding sites
13. Which of the following is FALSE about the contraction of sarcomeres?
A. The power stroke is responsible for motion, and involves the return of myosin heads to the 90° position
B. The formation of cross-bridges involves the attachment of myosin heads to tropomyosin binding sites
C. Requires high intracellular concentrations of both Ca+ and ATP
D. Becomes somewhat permanent as a result of ATP depletion
E. Is continuous given the constant release of ACh into the synaptic cleft, and availability of Ca+ in the cytoplasm
14. Ca+ returns to the sarcoplasmic reticulum
A. via active transport across the terminal cisternae membranes
B. with the help of SNAP-25 protein
C. faster in type I muscle than type II
D. during the contraction part of the muscle twitch
E. only in dying tissues
15. Type II muscle fibers
A. are alternatively called “slow twitch” fibers
B. are the primary constituent of small motor unit complexes
C. degenerate with age
D. have a slower rate of relaxation due to a lower activity of myosin ATP-ase
E. are found in higher concentration in endurance runner, than in sprinters
16. The strength of sarcomere contraction
A. is optimal with maximum actin-myosin overlap
B. is optimal with minimum actin-myosin overlap
C. is a direct result of the number of troponins available on actin
D. is sub-optimal due to over-contraction of resting human sarcomeres
E. can be increased with pep talks
17. Which of the following is TRUE about muscle twitches?
A. The first period is of identical length in both fast and slow twitch fibers
B. Period of contraction is the longest, relative to the other two periods
C. The last two periods are longer in type II fibers than type I fibers
D. Consists of three periods: excitation period, period of contraction, period of relaxation
E. Are shorter in type I fibers than type II fibers
18. As a person ages
A. Small motor units grow by recruiting de-innervated fibers from degenerating large motor units
B. Small motor units die out, resulting in the loss of fine motor function
C. Type I fibers become de-innervated
D. Fine motor function increases because small motor units pick up de-innervated type II fibers
E. The number or medium and large motor units decreases, while the number of small motor units increases
19. Which of the following is TRUE?
A. Marathon runners naturally are more likely to have a higher proportion of Type I to Type II muscle fibers.
B. Anaerobic glycolosis is the energy mechanism used to sustain long periods of exercise.
C. Glycolytic anaerobic production of ATP is the first energy-producing mechanism to be recruited by exercising
muscle.
D. Sprinters are naturally more likely to have a higher proportion of slow oxidative muscle fibers to fast glycolytic.
E. Aerobic oxidation will only provide ATP to muscle for the first 6-10 seconds of exercise.
20. Isometric contractions
A. can either be eccentric (shortening)or concentric (lengthening)
B. maintain the same tension throughout a contraction
C. maintain the same rate of extension/contraction throughout the motion
D. are what occurs when you try and fail to lift or move an object because it is too heavy
E. use more type II than type I muscle fibers
21. Fused tetany
A. is a result of hypocalcemia
B. is regularly achieved under normal physiological conditions
C. occurs after one maximum strength neural stimulation
D. is characterized by sustained, fluttering contractions
E. generates four times more force than a single muscle twitch
22. Which of the following is FALSE about muscle contractions?
A. The electrical excitation of a muscle fiber is a all or none event.
B. Contractile strength can be influenced by both the frequency and the strength of the nervous stimulus.
C. The strength of a muscle twitch is an all or none event.
D. Hypocalcemia can result in a decreased capacity of muscle to contract.
E. Lengthening contractions generate more force than concentric contractions.
23. The strength of muscle twitches can be influenced by all of the following EXCEPT
A. pH
B. hydration
C. levels of calcium present in the tissues from the previous contractions
D. stretch of the muscle
E. all of the above can influence the strength of muscle contractions
24. The correct order of muscle energy system use is
A. creatine phosphate, glycolysis, aerobic respiration
B. phosphagen system, oxidative phosphorylation, anaerobic fermentation
C. glycogen-lactic acid system, creatine kinase, aerobic respiration
D. none of the above
E. all of the above are valid, but depend on the type of motor unit (type I, type II, mixed)
25. Your favorite body system is
A. muscle
B. muscle
C. muscle
D. muscle
E. all of the above