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Multiple Choice
The diameter of a muscle fiber will predict which of the following characteristics?
A
The number of motor neurons innervating the fiber
B
The speed at which the muscle fiber contracts
C
The length of the muscle fiber
D
The amount of force the muscle fiber can generate
Verified step by step guidance
1
Understand the relationship between muscle fiber diameter and its functional characteristics. Larger muscle fibers generally have more myofibrils, which are the contractile units of the muscle, and this directly impacts the force they can generate.
Recall that the amount of force a muscle fiber can generate is proportional to the cross-sectional area of the fiber. Larger diameter fibers have a greater cross-sectional area, allowing them to produce more force.
Eliminate the incorrect options by analyzing their relationship to muscle fiber diameter: The number of motor neurons innervating a fiber is not determined by its diameter, as motor unit size is independent of fiber size. Similarly, the speed of contraction is more related to fiber type (e.g., fast-twitch vs. slow-twitch) than diameter. The length of the muscle fiber is also unrelated to its diameter.
Focus on the correct option: The diameter of a muscle fiber is directly related to the amount of force it can generate because larger fibers contain more contractile proteins (actin and myosin), which contribute to greater force production.
Conclude that the correct answer is 'The amount of force the muscle fiber can generate,' as this is the characteristic most directly influenced by the diameter of the muscle fiber.