Q: Which equation correctly represents the rapid replenishment of ATP in muscle cells using creatine phosphate?

$\text{Creatine~phosphate} + \text{ADP} \rightarrow \text{Creatine} + \text{ATP}$

Question 1

Which of the following statements best describes the sliding filament mechanism of muscle contraction?

Accepted Answer

Myosin heads bind to actin, bend, and pull actin filaments toward the center of the sarcomere, causing the sarcomere to shorten.

Question 2

A patient is experiencing muscle weakness and wasting, and genetic testing reveals a mutation in the dystrophin protein. Which disorder is most likely present?

Accepted Answer

Muscular dystrophy

Question 3

Which of the following is TRUE regarding the role of calcium in skeletal muscle contraction?

Accepted Answer

Calcium binds to troponin, causing the troponin–tropomyosin complex to shift and expose myosin binding sites on actin.

Question 4

During a muscle contraction, ATP is required for which of the following processes?

Accepted Answer

Both for energizing myosin heads to form cross-bridges and for detaching myosin heads from actin.

Question 5

Which equation correctly represents the rapid replenishment of ATP in muscle cells using creatine phosphate?

Accepted Answer

$	ext{Creatine~phosphate} + 	ext{ADP} ightarrow 	ext{Creatine} + 	ext{ATP}$

Question 6

A muscle cell is stimulated repeatedly at a high frequency, resulting in a sustained maximum contraction. What is this phenomenon called?

Accepted Answer

Tetanus

Question 7

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

Accepted Answer

Fast-twitch fibers have fewer mitochondria and rely more on anaerobic metabolism.

Question 8

Which of the following is a correct description of a motor unit?

Accepted Answer

A motor neuron and all the muscle cells it controls.

Question 9

A person is performing a plank exercise, maintaining a stationary position while generating muscle tension. Which type of muscle contraction is occurring?

Accepted Answer

Isometric contraction

Question 10

Which of the following statements about cardiac muscle is TRUE?

Accepted Answer

Cardiac muscle cells are joined by intercalated discs and have gap junctions that allow electrical stimulation of adjacent cells.

Question 11

Which of the following best describes the all-or-none principle in muscle physiology?

Accepted Answer

Individual muscle cells either fully contract or do not contract at all in response to a stimulus.

Question 12

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

Accepted Answer

Synthesizing hormones

Question 13

A patient presents with muscle cramps after intense exercise. Which of the following is the most likely cause?

Accepted Answer

Dehydration and ion imbalances

Question 14

Which of the following best describes the arrangement of actin and myosin filaments in smooth muscle?

Accepted Answer

Arranged in criss-crossed bundles, lacking sarcomeres and striations

Question 15

Which of the following is TRUE regarding the energy sources for muscle contraction?

Accepted Answer

Creatine phosphate can rapidly transfer a phosphate group to ADP to replenish ATP.

Question 16

Which of the following best explains why aerobic training increases muscle endurance?

Accepted Answer

It increases blood supply, mitochondria, and myoglobin in muscle cells.

Question 17

Which of the following is a characteristic of slow-twitch muscle fibers?

Accepted Answer

They have many mitochondria and are well-supplied with blood vessels.

Question 18

Which of the following best describes the process that occurs when nerve activation ends in skeletal muscle?

Accepted Answer

Calcium is pumped back into the sarcoplasmic reticulum, troponin–tropomyosin blocks myosin binding sites, and muscle relaxes.

Question 19

Which of the following is a plausible explanation for why a person with a thigh injury may have difficulty with fine motor control?

Accepted Answer

Thigh muscles have large motor units, resulting in more force but less fine control.

Question 20

Which of the following best describes the function of synergistic muscles?

Accepted Answer

They work together to create the same movement.

The Muscular System: Structure, Function, and Physiology

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