Question 1

Which of the following best describes an isometric muscle contraction?

Accepted Answer

Muscle tension increases but the muscle neither shortens nor lengthens.

Question 2

A weightlifter attempts to lift a barbell that is too heavy and cannot move it. Which type of contraction is occurring in the lifter's biceps?

Accepted Answer

Isometric contraction

Question 3

During a muscle twitch, which phase corresponds to the time when cross bridges are active and tension increases?

Accepted Answer

Contraction period

Question 4

Which equation correctly represents the direct phosphorylation of ADP by creatine phosphate (CP) in muscle cells?

Accepted Answer

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

Question 5

A sprinter running a 100-meter dash primarily relies on which energy system for muscle contraction?

Accepted Answer

Direct phosphorylation by creatine phosphate

Question 6

Which of the following best explains why muscle fatigue occurs during prolonged, intense exercise?

Accepted Answer

Ionic imbalances and depletion of ATP disrupt membrane potential and contraction.

Question 7

Which statement about motor units is correct?

Accepted Answer

A single motor neuron and all the muscle fibers it innervates form a motor unit.

Question 8

If a muscle fiber is stimulated so rapidly that no relaxation occurs between stimuli, what is this condition called?

Accepted Answer

Fused (complete) tetanus

Question 9

Which of the following is a correct description of the aerobic pathway for ATP production in muscle?

Accepted Answer

It uses oxygen to break down glucose, producing CO$$_2$$, H$$_2O$$, and ATP.

Question 10

Which muscle fiber type is most resistant to fatigue and best suited for endurance activities?

Accepted Answer

Slow oxidative fibers

Question 11

A marathon runner's muscles primarily use which energy system after the first 30 minutes of exercise?

Accepted Answer

Aerobic respiration

Question 12

Which factor does NOT directly increase the force of muscle contraction?

Accepted Answer

Decreased frequency of stimulation

Question 13

Which of the following best describes the role of calcium ions ($$\mathrm{Ca}^{2+}) in $$smooth muscle contraction?

Accepted Answer

$$\mathrm{Ca}^{2+}$$ binds to and activates calmodulin, which then activates myosin light chain kinase.

Question 14

Which adaptation is most likely to occur in skeletal muscle after several weeks of resistance exercise?

Accepted Answer

Muscle hypertrophy due to increased fiber size

Question 15

Which of the following is a characteristic unique to smooth muscle fibers compared to skeletal muscle fibers?

Accepted Answer

Smooth muscle fibers have a single nucleus and lack striations.

Question 16

A patient with paralyzed muscles due to nerve injury is at risk for which of the following?

Accepted Answer

Fibrous connective tissue replacing lost muscle tissue

Question 17

Which process is responsible for the replenishment of oxygen reserves, glycogen stores, and ATP after strenuous exercise?

Accepted Answer

Excess postexercise oxygen consumption (EPOC)

Question 18

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

Accepted Answer

Fast glycolytic fibers rely on anaerobic metabolism, which produces less ATP and more lactic acid.

Question 19

Which of the following is true regarding the recruitment of motor units during muscle contraction?

Accepted Answer

Motor units with the smallest muscle fibers are recruited first.

Question 20

Which of the following is a correct statement about the mechanism of smooth muscle contraction?

Accepted Answer

Smooth muscle contraction is initiated by calcium binding to calmodulin, not troponin.

Chapter 9 B -Muscle Contraction, Energy Systems, and Muscle Fiber Types: Study Notes for Anatomy & Physiology

Study Guide - Practice Questions