Question 1

Which type of muscle tissue is responsible for voluntary movements such as lifting a dumbbell, as shown in the first image?

Accepted Answer

Skeletal muscle

Question 2

Which structure in skeletal muscle fibers stores calcium ions necessary for muscle contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 3

What is the main function of the protein dystrophin in skeletal muscle fibers?

Accepted Answer

It links the cytoskeleton to the extracellular matrix, stabilizing the sarcolemma.

Question 4

During the sliding filament model of muscle contraction, which event directly causes the sarcomere to shorten?

Accepted Answer

Binding of myosin heads to actin and pulling the thin filaments toward the M line

Question 5

Which of the following best describes the role of ATP in muscle contraction and relaxation?

Accepted Answer

ATP is required for both the detachment of myosin heads from actin and the active transport of calcium back into the sarcoplasmic reticulum.

Question 6

A patient presents with muscle weakness and drooping eyelids. Laboratory tests reveal antibodies against acetylcholine receptors. What is the most likely diagnosis?

Accepted Answer

Myasthenia gravis

Question 7

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

Accepted Answer

Presence of intercalated discs with gap junctions

Question 8

Which process yields the greatest amount of ATP per molecule of glucose in muscle cells?

Accepted Answer

Aerobic respiration

Question 9

A muscle fiber is stimulated so frequently that it cannot relax between stimuli, resulting in a sustained contraction. What is this phenomenon called?

Accepted Answer

Tetanus

Question 10

Which of the following best explains why cardiac muscle cannot undergo tetanic contractions?

Accepted Answer

Cardiac muscle cells have long refractory periods due to their action potential properties.

Question 11

Which of the following is true regarding the energy systems used during a 100-meter sprint?

Accepted Answer

Creatine phosphate provides the initial ATP for maximal effort.

Question 12

Which muscle fiber type is most resistant to fatigue and is primarily used for endurance activities?

Accepted Answer

Slow oxidative fibers

Question 13

Which of the following best describes the role of myoglobin in muscle fibers?

Accepted Answer

It stores oxygen for aerobic metabolism.

Question 14

Which of the following events occurs first during excitation-contraction coupling in skeletal muscle?

Accepted Answer

Generation of an action potential along the sarcolemma

Question 15

Which of the following best explains why muscle fatigue occurs during prolonged, high-intensity exercise?

Accepted Answer

Imbalances in ions such as $$K^+$$, $$Ca^{2+}$$, and $$P_i$$ interfere with excitation-contraction coupling

Question 16

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

Accepted Answer

Peristalsis in the digestive tract

Question 17

Which of the following drugs would most likely cause muscle paralysis by blocking acetylcholine receptors at the neuromuscular junction?

Accepted Answer

Curare

Question 18

Which of the following best describes the 'all-or-none' response in muscle fibers?

Accepted Answer

A muscle fiber contracts to its full extent once threshold is reached.

Question 19

Which of the following is the correct sequence of events for ATP production during prolonged, moderate exercise?

Accepted Answer

Creatine phosphate → anaerobic glycolysis → aerobic respiration

Question 20

Which of the following best explains why Duchenne muscular dystrophy leads to muscle weakness?

Accepted Answer

Defective dystrophin leads to fragile sarcolemma and muscle fiber damage during contraction.

Muscle Tissue: Structure, Function, and Physiology

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