Question

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 1

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.