Part A Which of the following is true? Skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not. Smooth muscle lacks the thin and thick filaments characteristic of skeletal muscle. Skeletal muscle fibers tend to be shorter than smooth muscle fibers.

Skeletal muscle fibers contain sarcomeres, which are the fundamental units of muscle contraction, allowing them to contract with precision and force. In contrast, smooth muscle fibers do not have this organized structure, leading to a different contraction mechanism that is more gradual and sustained. In terms of length, skeletal muscle fibers are generally longer and multi-nucleated, enabling powerful contractions, while smooth muscle fibers are typically shorter and spindle-shaped, offering continuity and control in involuntary actions like peristalsis in the digestive system.