Question 1

Which of the following best explains the 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 2

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

Accepted Answer

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

Question 3

A patient is experiencing muscle weakness due to a defect in the neuromuscular junction. Which structure is most likely affected?

Accepted Answer

Acetylcholine receptors on the motor end plate

Question 4

Which of the following is NOT a function of the muscular system?

Accepted Answer

Synthesis of hormones

Question 5

During a muscle contraction, which event occurs immediately after the power stroke?

Accepted Answer

ATP binds to the myosin head, causing it to detach from actin.

Question 6

Which type of muscle tissue is responsible for voluntary movements?

Accepted Answer

Skeletal muscle

Question 7

Which protein directly blocks the myosin-binding sites on actin in a relaxed muscle?

Accepted Answer

Tropomyosin

Question 8

Which of the following best describes the role of acetylcholine at the neuromuscular junction?

Accepted Answer

It depolarizes the muscle fiber membrane, initiating an action potential.

Question 9

Which equation represents the conversion of creatine phosphate to ATP in muscle cells?

Accepted Answer

$$\mathrm{Creatine~phosphate + ADP \rightarrow Creatine + ATP}$$

Question 10

A marathon runner relies on which primary metabolic pathway for sustained ATP production during the race?

Accepted Answer

Aerobic respiration

Question 11

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

Accepted Answer

Isotonic contractions change muscle length, while isometric contractions do not.

Question 12

Which structure in the muscle fiber stores calcium ions necessary for contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 13

A patient with myasthenia gravis has impaired muscle contraction due to antibodies targeting which component?

Accepted Answer

Acetylcholine receptors

Question 14

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

Accepted Answer

Presence of intercalated discs

Question 15

Which process is responsible for the rapid removal of calcium ions from the cytoplasm to end muscle contraction?

Accepted Answer

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

Question 16

Which of the following best explains why ATP is required for muscle relaxation?

Accepted Answer

ATP is needed to detach myosin heads from actin filaments.

Question 17

Which of the following is a direct result of acetylcholine binding to its receptor on the muscle cell membrane?

Accepted Answer

Opening of sodium channels and depolarization of the sarcolemma

Question 18

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

Accepted Answer

Actin and myosin filaments slide past each other, shortening the sarcomere.

Question 19

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

Accepted Answer

Action potential → release of $$\mathrm{Ca$$^{2+}$$}$$ → troponin activation → cross-bridge formation

Question 20

Which muscle type is most resistant to fatigue and why?

Accepted Answer

Slow-twitch (Type I) fibers due to high mitochondrial density and aerobic metabolism

Chapter 9: Muscles and Muscle Tissue – Study Guide & Learning Objectives

Study Guide - Practice Questions