Question 1

Which of the following best describes the primary function of muscle tissue in the human body?

Accepted Answer

To convert chemical energy (ATP) into mechanical energy and heat

Question 2

A patient is diagnosed with a genetic disorder that prevents the production of functional troponin. Which of the following would most likely occur in their skeletal muscle fibers?

Accepted Answer

Tropomyosin would remain in place, blocking myosin-binding sites, preventing contraction

Question 3

Which of the following correctly matches the muscle type with its characteristics?

Accepted Answer

Smooth muscle: involuntary, non-striated, one nucleus

Question 4

During the sliding filament mechanism of muscle contraction, which of the following statements is TRUE?

Accepted Answer

Actin slides over myosin, increasing filament overlap without changing filament length

Question 5

Which connective tissue layer surrounds an individual muscle fiber?

Accepted Answer

Endomysium

Question 6

A toxin blocks acetylcholinesterase at the neuromuscular junction. What is the most likely effect on muscle contraction?

Accepted Answer

Muscle contraction will be prolonged and possibly lead to spasm due to persistent ACh

Question 7

Which of the following best explains why ATP is required for myosin to detach from actin during the cross-bridge cycle?

Accepted Answer

ATP binding to myosin causes a conformational change that releases myosin from actin

Question 8

Which of the following sarcomere regions decreases in size during muscle contraction?

Accepted Answer

I band and H zone

Question 9

A patient presents with muscle weakness. Laboratory tests reveal a defect in the T-tubules of their skeletal muscle fibers. Which process is most directly impaired?

Accepted Answer

Transmission of the action potential deep into the muscle fiber

Question 10

Which protein is responsible for the elasticity and recoil of the sarcomere after contraction?

Accepted Answer

Titin

Question 11

A muscle biopsy shows striated fibers with intercalated discs and a single nucleus per cell. Which type of muscle is this?

Accepted Answer

Cardiac muscle

Question 12

Which of the following correctly traces the signal path for skeletal muscle contraction?

Accepted Answer

Neuron action potential → ACh release → muscle action potential → T-tubules → SR → Ca$$^{2+}$$ release → troponin activation → cross-bridge formation

Question 13

If Ca$$^{2+} is $$removed from the sarcomere, what is the immediate effect on muscle contraction?

Accepted Answer

Tropomyosin blocks myosin-binding sites, preventing contraction

Question 14

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in muscle contraction?

Accepted Answer

It stores and releases Ca$$^{2+}$$ ions in response to an action potential

Question 15

Which of the following is a correct sequence of skeletal muscle organization from largest to smallest structure?

Accepted Answer

Whole muscle → fascicle → muscle fiber → myofibril → sarcomere

Question 16

A patient is exposed to a drug that prevents ATP hydrolysis in skeletal muscle. Which step of the cross-bridge cycle is directly inhibited?

Accepted Answer

Recocking of the myosin head

Question 17

Which of the following best explains why the H zone decreases in size during muscle contraction?

Accepted Answer

The actin filaments slide toward the M line, increasing overlap with myosin

Question 18

Which structure is responsible for anchoring actin filaments at the end of the sarcomere?

Accepted Answer

Z disc

Question 19

Which of the following best describes the function of tropomyosin in skeletal muscle contraction?

Accepted Answer

It blocks myosin-binding sites on actin when Ca$$^{2+} is $$absent

Question 20

A patient suffers a spinal cord injury that prevents voluntary control of their leg muscles. Which muscle type is primarily affected?

Accepted Answer

Skeletal muscle

Muscles & Muscle Tissue: Structure, Function, and Contraction

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