Question 1

Which of the following statements best describes the role of the sarcoplasmic reticulum in skeletal muscle contraction?

Accepted Answer

It stores and releases calcium ions ($$Ca^{2+}) $$necessary for contraction.

Question 2

During the crossbridge cycle, what event directly triggers the power stroke of the myosin head?

Accepted Answer

Release of $$P_i ($$inorganic phosphate) from the myosin head.

Question 3

A patient with McArdle’s disease cannot convert glycogen to glucose-6-phosphate. Which metabolic pathway is most directly affected in their skeletal muscle during exercise?

Accepted Answer

Anaerobic glycolysis

Question 4

Which muscle type is primarily responsible for moving blood through the circulatory system and is modulated by the endocrine system?

Accepted Answer

Cardiac muscle

Question 5

What is the main function of titin in the sarcomere?

Accepted Answer

It stabilizes the position of contractile elements and provides elasticity.

Question 6

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

ATP is no longer available to release myosin from actin.

Question 7

A muscle fiber is stimulated repeatedly before it can fully relax, resulting in a stronger contraction. What is this phenomenon called?

Accepted Answer

Summation

Question 8

Which equation correctly represents the reaction catalyzed by creatine kinase during rapid ATP regeneration in muscle?

Accepted Answer

$$\mathrm{Phosphocreatine} + \mathrm{ADP} \rightarrow \mathrm{Creatine} + \mathrm{ATP}$$

Question 9

Which of the following muscle fiber types is most resistant to fatigue and relies primarily on oxidative phosphorylation?

Accepted Answer

Slow-twitch fibers (ST, type I)

Question 10

A person is performing a biceps curl. Which muscle acts as the flexor, and what is its role?

Accepted Answer

Biceps; brings bones together

Question 11

Which of the following best describes the function of the transverse (T) tubules in skeletal muscle fibers?

Accepted Answer

They allow action potentials to penetrate deeper into the muscle fiber.

Question 12

Which protein complex binds calcium to initiate the removal of tropomyosin from the myosin-binding site on actin?

Accepted Answer

Troponin

Question 13

A muscle contraction that generates force without changing the overall length of the muscle is called:

Accepted Answer

Isometric contraction

Question 14

Which of the following is true regarding the length-tension relationship in skeletal muscle?

Accepted Answer

Maximum force is generated when the sarcomere is at its optimum length, neither too long nor too short.

Question 15

Which of the following best explains the difference between single-unit and multiunit smooth muscle?

Accepted Answer

Single-unit smooth muscle fibers contract together due to gap junctions, while multiunit fibers contract independently.

Question 16

Which of the following events occurs first during excitation-contraction coupling in skeletal muscle?

Accepted Answer

Acetylcholine binds to receptors on the sarcolemma.

Question 17

Which of the following is a correct sequence of events in the contraction-relaxation cycle of skeletal muscle?

Accepted Answer

Action potential → calcium release → troponin binds calcium → tropomyosin moves → crossbridge formation

Question 18

Which of the following is a major cause of muscle fatigue during extended submaximal exercise?

Accepted Answer

Depletion of glycogen stores

Question 19

Which of the following best describes the role of myoglobin in muscle fibers?

Accepted Answer

It binds oxygen, making it readily available for aerobic processes.

Question 20

A muscle cramp is best described as:

Accepted Answer

A sustained, painful contraction of muscle.

Muscle Tissue and Mechanics: Structure and Function in Human Physiology

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