Question 1

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

Accepted Answer

Myosin pulls on actin, causing the thin filament to slide inward and the sarcomere to shorten.

Question 2

During muscle contraction, what happens to the I band and H zone?

Accepted Answer

The I band diminishes in size, the H zone disappears, and the A band remains the same length.

Question 3

In order for cross bridges to form in contracting skeletal muscle, calcium must:

Accepted Answer

Bind to troponin, which moves the tropomyosin away from myosin-binding sites.

Question 4

Which of the following is the correct sequence of events for muscle contraction?

Accepted Answer

Motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments

Question 5

Curare poisoning blocks acetylcholine receptors at the neuromuscular junction. What would be the most likely symptom?

Accepted Answer

Muscle paralysis due to failure of action potential generation in muscle fibers.

Question 6

Which metabolic pathway provides the fastest source of ATP for muscle contraction but only lasts about 15 seconds?

Accepted Answer

Creatine phosphate pathway

Question 7

What is the main by-product of anaerobic glycolysis during intense exercise?

Accepted Answer

Lactic acid

Question 8

If a muscle fiber permanently stops producing ATP, what would happen to the actin-myosin interaction?

Accepted Answer

Myosin would be able to bind to actin but would not be able to detach, resulting in muscle rigidity.

Question 9

Which of the following best explains why heavy breathing continues after intense exercise?

Accepted Answer

To pay back oxygen debt by replenishing creatine phosphate, converting lactate to pyruvate, and reloading oxygen onto myoglobin.

Question 10

Which of the following is true about isometric muscle contraction?

Accepted Answer

The muscle develops tension but does not change length.

Question 11

During which type of muscle contraction does the muscle lengthen while maintaining tension?

Accepted Answer

Eccentric isotonic contraction

Question 12

Which of the following statements about the motor unit is correct?

Accepted Answer

A motor unit consists of one motor neuron and all the muscle fibers it supplies.

Question 13

Which of the following is a function of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine, terminating the signal at the synaptic cleft.

Question 14

Which of the following best describes the role of troponin in muscle contraction?

Accepted Answer

Troponin binds to calcium ions, causing a conformational change that moves tropomyosin away from actin's binding sites.

Question 15

Which of the following is NOT a cause of muscle fatigue?

Accepted Answer

Excessive release of acetylcholine at the neuromuscular junction

Question 16

Which of the following statements about complete (fused) tetanus is correct?

Accepted Answer

Complete tetanus involves development of maximum tension with no relaxation between stimuli.

Question 17

Which of the following best describes the role of the agonist muscle during movement?

Accepted Answer

It is the primary muscle responsible for a particular movement.

Question 18

Which of the following equations correctly represents the reaction catalyzed by creatine kinase?

Accepted Answer

$$\mathrm{Creatine\ phosphate} + \mathrm{ADP} \xrightarrow{\mathrm{creatine\ kinase}} \mathrm{Creatine} + \mathrm{ATP}$$

Question 19

Which process is responsible for the majority of ATP production during prolonged, moderate exercise?

Accepted Answer

Aerobic cellular respiration

Question 20

Which of the following best describes the function of a synergist muscle?

Accepted Answer

It assists the agonist by adding extra force or reducing unnecessary movement.

Muscles and Muscle Tissue: Contraction, Metabolism, and Types of Muscle Contraction

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