BIO230 Cuny NATURAL SCIENCES DEPARTMENT Exam 3

1) Which of the following is a recognized function of skeletal muscle?

A) produce movement

B) maintain posture

C) maintain body temperature

D) All of the answers are correct.

2) Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly

specialized for

A) conduction.

B) contraction.

C) peristalsis.

D) cushioning

3) The dense layer of connective tissue that surrounds an entire skeletal muscle is the

A) tendon.

B) epimysium.

C) endomysium.

D) perimysium.

4) The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent

muscle fibers together is the

A) endomysium.

B) perimysium.

C) epimysium.

D) superficial fascia

5) The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone

is called a(n)

A) fascicle.

B) tendon.

C) ligament.

D) epimysium.

6) Muscle fibers differ from "typical cells" in that muscle fibers

A) lack a plasma membrane.

B) have many nuclei.

C) are very small.

D) lack mitochondria.

7) The plasma membrane of skeletal muscle is called the

A) sarcolemma.

B) sarcomere.

C) sarcosome.

D) sarcoplasmic reticulum

8) The cytoplasm of skeletal muscle is called the

A) sarcolemma.

B) sarcoplasm.

C) sarcosome.

D) sarcoplasmic reticulum

9) The endoplasmic reticulum of skeletal muscle is called the

A) sarcolemma.

B) sarcomere.

C) sarcosome.

D) sarcoplasmic reticulum

10) The repeating contractile unit of a skeletal muscle fiber is the

A) sarcolemma.

B) sarcomere.

C) sarcoplasmic reticulum.

D) myofibril.

11) The region of the sarcomere that always contains only thin filaments is the

A) Z line.

B) I band.

C) H band.

D) A band.

12) The area in the center of the A band that contains no thin filaments is the

A) Z line.

B) M line.

C) H band.

D) I band.

13) What is released from sarcoplasmic reticulum?

A) sarcoplasm

B) acetylcholine

C) protein

D) calcium ions

14) What physiological process occurs in T tubes?

A) release of neurotransmitter

B) conduction of the action potential into the cell interior

C) activity of acetylcholinesterase

D) release of protein into the muscle fiber

15) Interactions between actin and myosin filaments of the sarcomere are responsible for

A) muscle fatigue.

B) the conduction of neural stimulation to the muscle fiber.

C) muscle contraction.

D) muscle relaxation.

16) At rest, active sites on the actin are blocked by

A) myosin molecules.

B) ATP molecules.

C) tropomyosin molecules.

D) calcium ions.

17) The thin filaments of striated muscle are made of which protein(s)?

A) actin

B) tropomyosin

C) troponin

D) All of the answers are correct

18) Physical evidence that supports the sliding filament theory of muscle contraction includes

A) constant distance between Z lines during contraction.

B) decreased width of the H band during contraction.

C) increased width of the I band during contraction.

D) decreased width of the A band during contraction

19) When a skeletal muscle fiber contracts,

A) the H bands and I bands get smaller.

B) the width of the A band remains constant.

C) the Z lines get closer together.

D) All of the answers are correct.

20) Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten,

the muscle fiber

A) lengthens.

B) shortens.

C) strengthens.

D) weakens

21) Which of the following is an ion that is more concentrated inside the cell than outside?

A) sodium

B) chloride

C) potassium

D) calcium

22) During the ________ phase of action potential development, voltage-gated sodium channels

are open.

A) repolarization

B) depolarization

C) refractory

D) threshold

23) If potassium channels were blocked, the ________ phase of the action potential would not

occur normally.

A) repolarization

B) depolarization

C) refractory

D) threshold

24) A membrane potential at -80 mV is

A) at threshold.

B) depolarized.

C) repolarized.

D) in the refractory period.

25) The Na+/K+ ion pump is responsible for

A) diffusing chloride across the plasma membrane.

B) transferring messages from enzyme-linked receptors to the cell nucleus.

C) maintaining the sodium/potassium concentration gradients constant.

D) initiating action potentials

26) Neurons and ________ have electrically excitable membranes that propagate action

potentials.

A) osteocytes

B) muscle cells

C) epithelial cells

D) proteins

27) Which of the following statements is not true about action potentials?

A) They can travel long distances within cells.

B) They occur in neurons.

C) They can travel in two directions.

D) They can be generated in less than 2 msec.

28) The narrow space between the synaptic terminal and the muscle fiber is the

A) synaptic knob.

B) motor end plate.

C) motor unit.

D) synaptic cleft.

29) The action potential is conducted into a skeletal muscle fiber by

A) motor end plates.

B) neuromuscular junctions.

C) transverse (T) tubules.

D) sarcoplasmic reticulum.

30) The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with

molecules of the neurotransmitter

A) epinephrine.

B) norepinephrine.

C) acetylcholine.

D) antidiuretic hormone

31) Communication between axons and muscle fibers occurs at specialized synapses called

A) junctional folds.

B) neuromuscular junctions.

C) motor end plates.

D) active sites.

32) How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal

muscle?

A) It would make the muscles more excitable.

B) It would produce uncontrolled muscle spasms.

C) It would cause spastic paralysis (muscles are contracted and unable to relax).

D) It would cause flaccid paralysis (muscles are relaxed and unable to contract).

33) When calcium ion binds to troponin,

A) tropomyosin moves aside and active sites on the actin are exposed.

B) active sites on the myosin are exposed.

C) actin heads will bind to myosin.

D) muscle relaxation occurs.

34) Which of the following acts as an ATPase (breaks ATP molecule) during the contraction

cycle of muscle?

A) actin molecules

B) troponin molecules

C) tropomyosin molecules

D) the head portion of the myosin molecule

35) When a muscle is stimulated repeatedly at a high rate, eliminating a relaxation phase, the

amount of tension gradually increases to a steady maximum tension. This is called

A) incomplete tetanus.

B) complete tetanus.

C) recruitment.

D) wave summation.

36) Joints can be classified structurally as

A) bony.

B) fibrous.

C) cartilaginous.

D) synovial.

E) All of the answers are correct

37) True or False:

The functions of synovial fluid are shock absorption and lubrication

38) Which of the following is an example of a ball-and-socket joint?

A) elbow

B) shoulder

C) ankle

D) wrist

39) A joint that permits only flexion and extension is a ________ joint.

A) saddle

B) hinge

C) pivot

D) gliding

40) A movement away from the midline of the body is termed

A) extension.

B) abduction.

C) adduction.

D) flexion.