Which of the following accurately describes the way in which a muscle moves?
a. no atp is needed in the contraction of a muscle.
b. when actin filaments are pulled toward the center of the sarcomere, the fiber shortens.
c. during contraction, cross-bridges pull the myosin to the center of the sarcomere.
d. interaction and attachment between myosin and actin cause a muscle fiber to relax.

Answer;

B. When actin filaments are pulled toward the center of the sarcomere, the fiber shortens.

Explanation;The events of muscle fiber shortening occurs with in the sacromeres in the fibers. Contraction of striated muscle fibers takes place as the sacromeres shorten as myosin heads pull on the actin filaments.Filament movement starts at the region or zone where thin and thick filaments overlap. Myofibril contains many sacromeres along its length and thuse myofibrils and muscle cells contract as the sacromeres contract.

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