Biology 1220



Biology 1220

Quiz #6 with answers

Name:________________________________________________________

Total Marks: 22 Total Pages: 3

(1) 1. The following are characteristics of muscle fibers except:

A) conductivity

B) elasticity

C) excitability

D) secretion

E) contractibility

(1) 2. The connective tissue layer that surrounds muscle fascicles is called:

A) the endomysium

B) the perimysium

C) the sarcolemma

D) the epimysium

E) the periosteum

(1) 3. The following are in order, from smallest to biggest:

A) myofilaments, myofibrils, muscle fiber, fascicle, muscle

B) myofilaments, muscle fiber, myofibrils, fascicle, muscle

C) myofilaments, myofibrils, fascicle, muscle fiber, muscle

D) myofilaments, fascicle, myofibrils, muscle fiber, muscle

E) myofibrils, myofilaments, muscle fiber, fascicle, muscle

(1) 4. Which one of the following statements is true?

A) Each skeletal muscle fiber is controlled by several neuromuscular junctions.

B) Skeletal muscles can contract without nervous system control.

C) Each skeletal muscle fiber is controlled by a neuron at a single neuromuscular junction.

D) A neuron must contract with a muscle fiber.

E) A single neuron can control only one muscle fiber.

(1) 5. What is most directly responsible for the contraction of a skeletal muscle fiber?

A) a neurotransmitter is released from a neuron

B) thin filaments slide alongside of thick filaments

C) an electrical signal passes through the intercalated disc

D) T tubules enter the sarcoplasm

E) an action potential travels along a neuron

(1) 6. Thick filaments are composed of:

A) myosin

B) actin

C) troponin

D) tropomyosin

E) titin

(1) 7. What is the basic functional unit of a skeletal muscle fiber?

A) the sarcolemma

B) the sarcoplasm

C) the sarcomere

D) the sarcoplasmic reticulum

E) the transverse tubule

E. the terminal cistern

(1) 8. Which of the following is a regulatory protein of the muscle fiber?

A) troponin

B) myosin

C) dystrophin

D) actin

E) collagen

E. cross-bridges

(2) 9. What is a motor unit?

one nerve fiber and all of the muscle fibers that it innervates is called a motor unit

(1) 10. Name one component of the sarcoplasm.

Myofibrils, glycogen, myoglobin, sarcoplasmic reticulum, any of the usual organelles associated with a cell including ribosomes, mitochondria, Golgi etc.

(2) 11. What is the function of the transverse tubules (T-tubules)?

T-tubules conduct the action potential from the sarcolemma to the sarcoplasmic reticulum in the sarcoplasm

(2) 12. If Ca2+ (calcium ions) are prevented from being released into the sarcoplasm of a skeletal muscle cell, what is the result? Refer to the muscle proteins involved.

There will be no calcium binding to troponin, troponin/tropomyosin will not move away from the active sites on actin, myosin will not be able to form cross-bridges and there will be no contraction

(2) 13. Immediately after a neurotransmitter has diffused across the synaptic cleft and engaged its receptor, what happens to the sarcolemma?

Gated channels open, sodium and potassium ions flow across the membrane, which depolarizes the cell and an action potential is initiated in the sarcolemma

(5) 17. Complete one of the following: Use labeled drawings if you’d like.

a. Describe the steps involved in transferring a signal from a neuron to a skeletal muscle, which is the excitation phase of muscle fibers.

b. Describe excitation-contraction coupling (that is, the steps after development of the muscle fiber action potential that allows contraction to proceed).

c. Describe the contraction cycle.

d. Describe the relaxation phase of muscle fibers.

Go directly to the notes starting on page 7 of the notes

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