Question 1

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in skeletal muscle contraction?

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$necessary for muscle contraction.

Question 2

A patient is unable to relax their muscles after contraction. Which of the following is the most likely cause?

Accepted Answer

A deficiency in ATP, preventing detachment of myosin heads from actin.

Question 3

Which structure is responsible for carrying the action potential deep into the muscle fiber, triggering calcium release?

Accepted Answer

T-tubule (transverse tubule)

Question 4

During intense exercise, when oxygen is limited, what is the fate of pyruvate produced by glycolysis in skeletal muscle?

Accepted Answer

It is converted to lactic acid, which is transported to the liver.

Question 5

Which of the following is the correct sequence of events in the cross-bridge cycle during muscle contraction?

Accepted Answer

Cross-bridge formation, power stroke, detachment, cocking of myosin head

Question 6

Which protein complex blocks the active sites on actin in a resting muscle fiber?

Accepted Answer

Troponin-tropomyosin complex

Question 7

What is the primary function of acetylcholinesterase (AChE) at the neuromuscular junction?

Accepted Answer

It degrades acetylcholine, terminating the muscle stimulation.

Question 8

Which of the following best explains why skeletal muscle fibers are multinucleate?

Accepted Answer

They require multiple copies of genes to produce large amounts of proteins for contraction.

Question 9

A muscle fiber is unable to contract even though acetylcholine is released at the neuromuscular junction. Which of the following is the most likely explanation?

Accepted Answer

The acetylcholine receptors on the sarcolemma are blocked or nonfunctional.

Question 10

Which of the following equations correctly represents the breakdown of creatine phosphate to regenerate ATP during muscle contraction?

Accepted Answer

$$\mathrm{Creatine\;phosphate + ADP \xrightarrow{creatine\;kinase} Creatine + ATP}$$

Question 11

Which layer of connective tissue surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 12

Which of the following best describes the sliding filament model of muscle contraction?

Accepted Answer

Thin filaments slide past thick filaments, shortening the sarcomere.

Question 13

Which metabolic pathway provides the greatest yield of ATP per glucose molecule during muscle activity?

Accepted Answer

Aerobic respiration

Question 14

Which of the following is NOT a function of skeletal muscle?

Accepted Answer

Pumping blood throughout the body

Question 15

What would happen if the perimysium of a muscle was damaged?

Accepted Answer

Muscle fascicles would lose structural support and organization.

Question 16

Which of the following best explains why muscle contraction cannot continue indefinitely during intense exercise?

Accepted Answer

ATP and creatine phosphate stores are depleted, and oxygen becomes limited.

Question 17

Which of the following is the correct order of structures from largest to smallest in skeletal muscle?

Accepted Answer

Muscle, fascicle, fiber, myofibril, myofilament

Question 18

Which of the following statements about glycolysis in muscle cells is correct?

Accepted Answer

It produces 2 ATP and 2 pyruvate molecules per glucose molecule.

Question 19

What is the role of satellite cells in skeletal muscle?

Accepted Answer

They are stem cells involved in muscle tissue repair.

Muscle Tissue: Structure, Function, and Contraction Mechanisms

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