Question 1

Which of the following best describes the sequence of events at the neuromuscular junction leading to muscle contraction?

Accepted Answer

Acetylcholine is released from the motor neuron, binds to receptors on the sarcolemma, causing sodium ions to enter the muscle fiber, leading to depolarization and an action potential.

Question 2

Which structure is the smallest functional unit of a vertebrate skeletal muscle responsible for contraction?

Accepted Answer

Sarcomere

Question 3

According to the sliding filament model, which event directly causes the shortening of the sarcomere during muscle contraction?

Accepted Answer

The myosin heads bind to actin and pull the thin filaments toward the center of the sarcomere.

Question 4

What is the primary role of calcium ions ($$\mathrm{Ca$$^{2+}$$}) in $$skeletal muscle contraction?

Accepted Answer

They bind to troponin, causing a conformational change that exposes myosin-binding sites on actin.

Question 5

Which process is essential for muscle relaxation after contraction?

Accepted Answer

Active transport of $$\mathrm{Ca$$^{2+}$$}$$ back into the sarcoplasmic reticulum

Question 6

A marathon runner primarily uses which type of skeletal muscle fiber during a race?

Accepted Answer

Type I (slow-twitch oxidative) fibers

Question 7

Which of the following best describes the difference between exoskeletons and endoskeletons?

Accepted Answer

Exoskeletons are external and provide protection, while endoskeletons are internal and allow for greater growth and flexibility.

Question 8

Which form of locomotion is most energetically efficient for animals covering long distances?

Accepted Answer

Swimming

Question 9

During a muscle contraction, what happens to the length of the A band and the I band in the sarcomere?

Accepted Answer

The A band remains the same length, while the I band shortens.

Question 10

Which of the following scenarios would most likely result in muscle fatigue due to lactic acid buildup?

Accepted Answer

A sprinter running a 100-meter dash at maximum effort

Question 11

Which equation best represents the hydrolysis of ATP during muscle contraction?

Accepted Answer

$$\mathrm{ATP + H_2O \rightarrow ADP + P_i + energy}$$

Question 12

Which of the following is a characteristic of hydrostatic skeletons?

Accepted Answer

They rely on fluid-filled compartments to maintain shape and allow movement.

Question 13

Which of the following best explains why calcium channel blockers can reduce muscle contraction strength?

Accepted Answer

They prevent $$\mathrm{Ca$$^{2+}$$}$$ from entering the muscle cell, reducing troponin activation and cross-bridge formation.

Question 14

Which muscle fiber type is most resistant to fatigue and why?

Accepted Answer

Type I (slow-twitch oxidative) fibers, due to their high mitochondrial content and aerobic metabolism.

Question 15

Which of the following is the correct order of structures from largest to smallest in vertebrate skeletal muscle?

Accepted Answer

Muscle, fascicle, muscle fiber, myofibril, sarcomere

Question 16

Which of the following best describes the energetic cost of flying compared to running and swimming?

Accepted Answer

Flying generally requires more energy per unit distance than running or swimming.

Question 17

Which event must occur for the cross-bridge cycle to end and muscle relaxation to begin?

Accepted Answer

$$\mathrm{Ca$$^{2+}$$} is $$actively transported back into the sarcoplasmic reticulum.

Question 18

Which of the following is a similarity between exoskeletons and endoskeletons?

Accepted Answer

Both provide structural support and sites for muscle attachment.

Question 19

Which of the following best explains why fast-twitch glycolytic fibers fatigue more quickly than slow-twitch oxidative fibers?

Accepted Answer

They rely primarily on anaerobic metabolism, which produces less ATP and more lactic acid.

Question 20

Which of the following is a direct result of acetylcholine binding to receptors on the muscle cell membrane at the neuromuscular junction?

Accepted Answer

An influx of sodium ions ($$\mathrm{Na^+}) $$into the muscle cell, leading to depolarization.

Muscle Structure, Function, and Locomotion: Study Guide

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