Q: Which equation correctly represents the net ATP yield from glycolysis of one glucose molecule in skeletal muscle?

$$2 \text{ ATP} + 2 \text{ pyruvate}$$

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, which are essential for initiating muscle contraction.

Question 2

During the contraction of a skeletal muscle fiber, which of the following changes occur in the sarcomere?

Accepted Answer

The I bands and H band narrow, while the A band remains the same width.

Question 3

A patient is experiencing muscle weakness due to a genetic defect that prevents the formation of myosin heads. Which step in the contraction cycle would be directly affected?

Accepted Answer

Formation of cross-bridges between actin and myosin

Question 4

Which equation correctly represents the net ATP yield from glycolysis of one glucose molecule in skeletal muscle?

Accepted Answer

$$2 	ext{ ATP} + 2 	ext{ pyruvate}$$

Question 5

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

ATP is depleted, preventing the detachment of myosin heads from actin.

Question 6

A muscle is stimulated at a frequency greater than 50 times per second, and the tension increases because the next stimulus arrives before the previous relaxation phase is complete. What is this phenomenon called?

Accepted Answer

Wave summation

Question 7

Which of the following is a unique structural feature of cardiac muscle cells compared to skeletal muscle fibers?

Accepted Answer

Presence of intercalated discs containing gap junctions and desmosomes

Question 8

Which of the following best describes the function of creatine phosphate (CP) in muscle contraction?

Accepted Answer

It donates a phosphate group to ADP to rapidly regenerate ATP during the initial seconds of contraction.

Question 9

A marathon runner is able to sustain muscle activity for long periods. Which type of muscle fiber is most abundant in their leg muscles, and why?

Accepted Answer

Slow fibers, because they have many mitochondria and high myoglobin content for aerobic endurance.

Question 10

Which of the following statements about smooth muscle is correct?

Accepted Answer

Smooth muscle cells lack sarcomeres and are non-striated.

Question 11

A patient with a deficiency in acetylcholinesterase (AChE) would most likely experience which of the following symptoms?

Accepted Answer

Prolonged muscle contraction due to continued presence of acetylcholine in the synaptic cleft

Question 12

Which of the following best explains the length-tension relationship in skeletal muscle fibers?

Accepted Answer

Maximum tension is produced when there is optimal overlap between thick and thin filaments, allowing the greatest number of cross-bridges to form.

Question 13

Which of the following is a function of muscle tone in skeletal muscles?

Accepted Answer

Stabilizing the positions of bones and joints without causing movement

Question 14

Which of the following best describes the process of excitation-contraction coupling in skeletal muscle?

Accepted Answer

An action potential in the sarcolemma triggers calcium release from the sarcoplasmic reticulum, leading to cross-bridge formation.

Question 15

Which of the following is true regarding isometric muscle contractions?

Accepted Answer

The muscle develops tension but does not change length.

Question 16

A patient is unable to maintain posture and balance due to a loss of involuntary muscle twitches. Which structure is most likely affected?

Accepted Answer

Motor units responsible for muscle tone

Question 17

Which hormone increases both the duration of stimulation and the force of muscle contraction?

Accepted Answer

Epinephrine

Question 18

Which of the following best explains why fast muscle fibers fatigue more quickly than slow fibers?

Accepted Answer

They have fewer mitochondria and rely more on anaerobic metabolism.

Question 19

Which of the following is a characteristic of multiunit smooth muscle cells?

Accepted Answer

Each cell may be connected to more than one motor neuron and contracts independently.

Muscle Tissue: Structure, Function, and Physiology

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