Q: Which of the following is the correct formula for the hydrolysis of ATP during muscle contraction?

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy}$$

Question 1

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

Accepted Answer

Muscles convert chemical energy (ATP) into mechanical energy to exert force.

Question 2

Which connective tissue layer surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 3

A patient is experiencing muscle weakness due to a lack of acetylcholine at the neuromuscular junction. Which step in muscle contraction is most directly affected?

Accepted Answer

Transmission of the action potential across the synaptic cleft

Question 4

Which of the following is the correct sequence of events for excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential travels along sarcolemma $$\rightarrow T-$$tubules $$\rightarrow$$ calcium release from sarcoplasmic reticulum $$\rightarrow$$ exposure of active sites on actin

Question 5

Which property of muscle tissue allows it to respond to a stimulus by generating an electrical signal?

Accepted Answer

Excitability

Question 6

During a muscle twitch, which phase corresponds to the time when calcium ions are actively being pumped back into the sarcoplasmic reticulum?

Accepted Answer

Relaxation phase

Question 7

A marathon runner relies primarily on which type of muscle fibers and what is their main energy source?

Accepted Answer

Slow-twitch fibers; aerobic metabolism

Question 8

Which of the following best explains why cardiac muscle cells can contract in a coordinated manner?

Accepted Answer

They are connected by intercalated discs containing gap junctions.

Question 9

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

Accepted Answer

Pumping blood

Question 10

A muscle fiber is unable to relax after contraction. Which of the following is the most likely cause?

Accepted Answer

Failure to remove calcium ions from the cytosol

Question 11

Which of the following best describes the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions change muscle length, isometric contractions do not.

Question 12

Which of the following is the correct formula for the hydrolysis of ATP during muscle contraction?

Accepted Answer

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy}$$

Question 13

Which of the following best explains why smooth muscle can sustain contractions for longer periods than skeletal muscle?

Accepted Answer

Smooth muscle uses less ATP and has slower cross-bridge cycling.

Question 14

A patient with a genetic defect in the protein dystrophin would most likely have problems with which of the following?

Accepted Answer

Transmitting force from the sarcomere to the cell membrane

Question 15

Which of the following is a correct statement about the role of calcium in muscle contraction?

Accepted Answer

Calcium binds to troponin, causing tropomyosin to move and expose active sites on actin.

Question 16

Which of the following best describes the difference between fast-twitch and slow-twitch muscle fibers?

Accepted Answer

Fast-twitch fibers fatigue quickly and rely on anaerobic metabolism; slow-twitch fibers are fatigue-resistant and rely on aerobic metabolism.

Question 17

Which of the following is the functional unit of contraction in a skeletal muscle fiber?

Accepted Answer

Sarcomere

Question 18

During repeated stimulation of a muscle, which phenomenon describes the additive effect of individual twitches leading to a stronger contraction?

Accepted Answer

Summation

Question 19

Which of the following best explains why muscle fatigue occurs during prolonged activity?

Accepted Answer

ATP production fails to keep up with demand, leading to accumulation of metabolic byproducts.

Question 20

A muscle is contracting but not changing length while holding a heavy object steady. What type of contraction is this?

Accepted Answer

Isometric

Muscle Tissue: Structure, Function, and Physiology

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