Question 1

Which of the following statements best describes the role of the sarcolemma in skeletal muscle fibers?

Accepted Answer

It is the plasma membrane of the muscle fiber, responsible for conducting action potentials.

Question 2

During the sliding filament model of muscle contraction, which event occurs at the molecular level?

Accepted Answer

Thin filaments slide past thick filaments, increasing the overlap between actin and myosin.

Question 3

Which of the following best explains why indirect muscle attachments are more common than direct attachments?

Accepted Answer

Indirect attachments allow for greater durability and can span rough bony projections.

Question 4

A patient presents with muscle weakness and elevated levels of creatine kinase. Genetic testing reveals a mutation in the gene encoding dystrophin. Which condition is most likely?

Accepted Answer

Duchenne muscular dystrophy

Question 5

Which of the following is the correct sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential → Ca2+ release from SR → Ca2+ binds troponin → Tropomyosin moves → Cross bridge formation

Question 6

Which muscle fiber type is most resistant to fatigue and why?

Accepted Answer

Slow oxidative fibers, because they use aerobic metabolism and contain myoglobin.

Question 7

A muscle is stimulated repeatedly with the same strength stimulus, and the contractions become progressively stronger. This phenomenon is known as:

Accepted Answer

Treppe (the staircase effect)

Question 8

Which of the following equations correctly represents the reaction catalyzed by creatine kinase during short bursts of muscle activity?

Accepted Answer

$$\mathrm{CP} + \mathrm{ADP} \rightarrow \mathrm{Creatine} + \mathrm{ATP}$$

Question 9

Which of the following best describes the function of the sodium-potassium ATPase pump in muscle fibers?

Accepted Answer

It restores ionic gradients after an action potential by moving 3 Na+ out and 2 K+ in per ATP hydrolyzed.

Question 10

A muscle contraction in which tension increases but the muscle does not change length is called:

Accepted Answer

Isometric contraction

Question 11

Which of the following is a unique feature of cardiac muscle tissue compared to skeletal muscle tissue?

Accepted Answer

Presence of intercalated discs for electrical coupling

Question 12

Which protein blocks the myosin binding sites on actin in a relaxed skeletal muscle fiber?

Accepted Answer

Tropomyosin

Question 13

Which of the following best explains why lactic acid accumulates in muscles during intense exercise?

Accepted Answer

Aerobic respiration is unable to keep up with ATP demand, so pyruvic acid is converted to lactic acid.

Question 14

Which of the following is true regarding the arrangement of connective tissue sheaths in skeletal muscle?

Accepted Answer

The perimysium surrounds fascicles, which are bundles of muscle fibers.

Question 15

Which of the following best describes the role of calcium ions ($$\mathrm{Ca}^{2+}) in $$muscle contraction?

Accepted Answer

They bind to troponin, causing a conformational change that moves tropomyosin and exposes myosin binding sites on actin.

Question 16

A marathon runner is most likely to have a higher proportion of which muscle fiber type in their leg muscles?

Accepted Answer

Slow oxidative fibers

Question 17

Which of the following best describes the function of the motor end plate at the neuromuscular junction?

Accepted Answer

It contains highly folded regions of the sarcolemma with acetylcholine receptors.

Question 18

Which of the following is a correct description of the H zone in a sarcomere?

Accepted Answer

It is the region within the A band where thick and thin filaments do not overlap.

Question 19

Which of the following best explains why muscle tone is important for the body?

Accepted Answer

It keeps muscles firm, healthy, and ready to respond to stimulation.

Question 20

Which of the following is a unique property of smooth muscle compared to skeletal muscle?

Accepted Answer

Ability to divide and undergo hyperplasia in response to hormones

Comprehensive Study Notes: Muscles and Muscle Tissue (Chapter 9)

Study Guide - Practice Questions

Study Guide - Flashcards