Question 1

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

Accepted Answer

Troponin binds to calcium ions, causing a conformational change that moves tropomyosin and exposes myosin binding sites on actin.

Question 2

During the sliding filament theory of muscle contraction, which event directly results in the shortening of the sarcomere?

Accepted Answer

Power stroke of myosin heads pulling actin filaments toward the center of the sarcomere.

Question 3

Which of the following correctly matches the muscle fiber type with its primary characteristic?

Accepted Answer

Type IIb fibers: Fast contraction, low fatigue resistance

Question 4

What is the primary function of the Z disk in the sarcomere?

Accepted Answer

It anchors the thin filaments and defines the boundary of each sarcomere.

Question 5

A patient presents with muscle weakness and delayed relaxation after contraction. Which protein malfunction is most likely responsible?

Accepted Answer

Defective myosin ATPase, resulting in impaired ATP hydrolysis and crossbridge detachment

Question 6

Which equation best represents the relationship between muscle force ($$F$$), cross-sectional area ($$A$$), and specific tension ($$T$$)?

Accepted Answer

$$F = A 	imes T$$

Question 7

Which of the following statements about the sarcoplasmic reticulum is correct?

Accepted Answer

It releases calcium ions to initiate muscle contraction.

Question 8

In the context of muscle contraction, what is the role of myosin ATPase?

Accepted Answer

It hydrolyzes ATP to provide energy for the power stroke.

Question 9

Which of the following best explains the difference between hypertrophy and hyperplasia in skeletal muscle?

Accepted Answer

Hypertrophy is an increase in the size of existing muscle fibers; hyperplasia is an increase in the number of muscle fibers.

Question 10

Which of the following is a regulatory protein involved in muscle contraction?

Accepted Answer

Troponin

Question 11

A muscle fiber is unable to relax after contraction, resulting in a state known as rigor. What is the most likely cause?

Accepted Answer

Depletion of ATP, preventing crossbridge detachment

Question 12

Which structure is responsible for transmitting the action potential deep into the muscle fiber?

Accepted Answer

T-tubules

Question 13

Which of the following best describes the organization of the sarcomere?

Accepted Answer

It is defined by the region between two Z disks.

Question 14

Which of the following is true regarding the force of muscle contraction?

Accepted Answer

It increases with the number of active motor units and the frequency of stimulation.

Question 15

Which protein acts as an accessory protein, providing structural support to the thin filament in the sarcomere?

Accepted Answer

Nebulin

Question 16

A marathon runner is likely to have a higher proportion of which muscle fiber type?

Accepted Answer

Type I fibers

Question 17

Which of the following best describes the function of crossbridges during muscle contraction?

Accepted Answer

They form connections between actin and myosin, allowing force generation and filament sliding.

Question 18

Which of the following is NOT a step in the excitation-contraction coupling process?

Accepted Answer

Release of sodium ions from the sarcoplasmic reticulum

Question 19

Which of the following equations correctly represents the calculation of muscle tension ($$T) $$given force ($$F) $$and cross-sectional area ($$A$$)?

Accepted Answer

$$T = \frac{F}{A}$$

Question 20

Which of the following mechanisms is most responsible for muscle fatigue during prolonged activity?

Accepted Answer

Accumulation of lactic acid and depletion of ATP

Muscle Tissue Structure, Organization, and Contraction Mechanisms

Study Guide - Practice Questions