Question 1

A marathon runner, like the one shown crossing the finish line in the first image, relies primarily on which type of skeletal muscle fiber for performance, and why?

Accepted Answer

Slow twitch oxidative fibers, because they are fatigue-resistant and support aerobic metabolism.

Question 2

Which of the following best explains why sprinters, like those shown in the second image, have a higher proportion of fast twitch muscle fibers?

Accepted Answer

Fast twitch fibers contract rapidly and generate high force but fatigue quickly.

Question 3

Referencing the table of muscle fiber properties, which muscle fiber type would you expect to predominate in the postural muscles of the back, and why?

Accepted Answer

Slow fibers, because they are fatigue-resistant and support prolonged activity.

Question 4

A muscle biopsy reveals fibers with a small diameter, dark color, and abundant mitochondria. Which type of muscle fiber is this, and what is its primary function?

Accepted Answer

Slow twitch oxidative fiber; sustained, fatigue-resistant contractions.

Question 5

Which of the following best describes the process of muscle hypertrophy?

Accepted Answer

Increase in the diameter of existing muscle fibers due to synthesis of more actin and myosin.

Question 6

During a 100-meter sprint, which metabolic pathway is primarily responsible for ATP production after the initial ATP/CP reserves are depleted?

Accepted Answer

Glycolysis (anaerobic metabolism).

Question 7

Which of the following changes would you expect in skeletal muscle as a result of aging?

Accepted Answer

Decrease in muscle size, strength, and endurance due to loss of myofibrils and myoglobin.

Question 8

A patient presents with muscle weakness and cramping after severe dehydration. Which electrolyte imbalance is most likely responsible for these symptoms?

Accepted Answer

Hyponatremia

Question 9

Which of the following best explains why cardiac muscle cells are able to contract in a coordinated, rhythmic manner?

Accepted Answer

They are connected by intercalated discs containing gap junctions and desmosomes.

Question 10

Which of the following is a primary difference between smooth muscle and skeletal muscle contraction?

Accepted Answer

Smooth muscle can maintain tension over a wide range of lengths due to plasticity, while skeletal muscle cannot.

Question 11

A person is training for a long-distance cycling event. Which adaptation would you expect in their skeletal muscles after several months of aerobic training?

Accepted Answer

Increased number of mitochondria and capillaries in muscle fibers.

Question 12

Which of the following best describes the effect of organophosphate insecticides on muscle contraction?

Accepted Answer

They block acetylcholine esterase, leading to more acetylcholine in the synaptic gap and spastic paralysis.

Question 13

Which of the following equations correctly represents the relationship between force, cross-sectional area, and muscle tension?

Accepted Answer

$$F = \sigma \cdot A$$

Question 14

A patient with Duchenne’s muscular dystrophy is unable to produce normal dystrophin protein. Which of the following is a likely consequence?

Accepted Answer

Progressive muscle weakness and early onset muscle atrophy.

Question 15

Which of the following best explains why a muscle cramp (spasm) occurs?

Accepted Answer

Sudden, strong, unwanted contraction of a muscle.

Question 16

Which of the following best describes the control mechanism for cardiac muscle contraction?

Accepted Answer

Controlled by pacemaker cells and the autonomic nervous system.

Question 17

Which of the following is a characteristic of fast twitch glycolytic fibers?

Accepted Answer

Large diameter and high glycolytic enzyme concentration.

Question 18

A person experiences muscle atrophy after being immobilized in a cast for several weeks. Which of the following best explains this phenomenon?

Accepted Answer

Decrease in the diameter of muscle fibers due to loss of actin and myosin.

Question 19

Which of the following best describes the energy source for skeletal muscle during moderate activity?

Accepted Answer

Aerobic metabolism in mitochondria.

Question 20

Which of the following is a distinguishing feature of cardiac muscle tissue visible in the provided histological images?

Accepted Answer

Presence of intercalated discs connecting adjacent cells.

Muscle Performance and Muscle Tissue Types: Structure, Function, and Disorders

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