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

$$\text{Creatine phosphate} + \text{ADP} \rightarrow \text{Creatine} + \text{ATP}$$

Question 1

Which of the following best describes the latent period of a muscle twitch as shown in a myogram?

Accepted Answer

The period after a single stimulus when excitation-contraction coupling occurs, but no muscle tension is seen.

Question 2

A muscle fiber is stimulated by two action potentials in rapid succession, resulting in increased force. What is the physiological basis for this phenomenon?

Accepted Answer

Additional Ca$$^{2+}$$ released with the second stimulus stimulates more shortening, leading to wave (temporal) summation.

Question 3

Which of the following is TRUE regarding the size principle of recruitment in skeletal muscle contraction?

Accepted Answer

Motor units with smallest muscle fibers are recruited first, and larger units are recruited as stimulus intensity increases.

Question 4

During isotonic contraction, which of the following events occurs?

Accepted Answer

Muscle tension exceeds the load, causing the muscle to shorten and move the load.

Question 5

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

Accepted Answer

$$	ext{Creatine phosphate} + 	ext{ADP} ightarrow 	ext{Creatine} + 	ext{ATP}$$

Question 6

A sprinter uses which energy system predominantly during the first 10 seconds of a race?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate (CP)

Question 7

Which of the following best explains muscle fatigue during prolonged, high-intensity exercise?

Accepted Answer

Ionic imbalances, increased inorganic phosphate, and decreased glycogen contribute to fatigue.

Question 8

Which of the following statements about muscle tone is correct?

Accepted Answer

Muscle tone is a constant, slightly contracted state due to spinal reflexes and alternating activation of motor units.

Question 9

Which muscle fiber type is best suited for endurance activities such as maintaining posture?

Accepted Answer

Slow oxidative fibers

Question 10

A muscle fiber is stretched to 170% of its resting length. What happens to its ability to generate tension?

Accepted Answer

Tension decreases because filaments do not overlap enough for cross bridge formation.

Question 11

Which of the following is a characteristic of unfused (incomplete) tetanus?

Accepted Answer

Muscle tension fluctuates, producing a quivering contraction due to partial relaxation between stimuli.

Question 12

Which of the following best describes an isometric contraction?

Accepted Answer

Muscle tension increases but the muscle neither shortens nor lengthens.

Question 13

Which of the following factors increases the force of skeletal muscle contraction?

Accepted Answer

High frequency of stimulation, large number of muscle fibers recruited, and optimal sarcomere length.

Question 14

During resistance exercise, such as weight lifting, which adaptation occurs in skeletal muscle?

Accepted Answer

Muscle hypertrophy due to increased fiber size, mitochondria, myofilaments, and glycogen stores.

Question 15

Which of the following is TRUE regarding the relationship between load and velocity of muscle contraction?

Accepted Answer

The greater the load, the slower the muscle contracts.

Question 16

Which metabolic pathway produces the most ATP per glucose molecule during muscle contraction?

Accepted Answer

Aerobic respiration

Question 17

Which of the following best describes concentric contraction?

Accepted Answer

Muscle shortens and does work, such as picking up a book.

Question 18

Which of the following is a function of ATP in muscle contraction?

Accepted Answer

ATP is required to move and detach cross bridges, pump Ca$$^{2+}$$ back into SR, and restore ion gradients after excitation-contraction coupling.

Question 19

Which muscle fiber type is most resistant to fatigue and best suited for prolonged, low-intensity activities?

Accepted Answer

Slow oxidative fibers

Question 20

Which of the following statements about motor units is correct?

Accepted Answer

A motor unit consists of a motor neuron and all the muscle fibers it supplies.

Whole Skeletal Muscle Contraction: Structure, Function, and Energy in Muscle Physiology

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