Question

Which of the following accurately describes the way in which a muscle moves? A.When actin filaments are pulled toward the center of the sarcomere, the fiber shortens. B.Interaction and attachment between myosin and actin cause a muscle fiber to relax. C.No ATP is needed is the contraction of a muscle. D.During contraction, cross- bridges pull the myosin to the center of the sarcomere.

Answer 1

The correct answer is this one: "A.When actin filaments are pulled toward the center of the sarcomere, the fiber shortens." The statement that accurately describes the way in which a muscle moves is when actin filaments are pulled toward the center of the sarcomere, the fiber shortens

Answer 2

Answer:

The correct answer would be option A.

It can be best explained with the help of sliding filament theory which states that muscle contraction takes place by sliding of actin (thin filament) and myosin (thick filament). past each other.

Calcium ions released as a result of action potential bind to the troponin on actin which unmasks the active sites.

Myosin heads bind to these exposed active sites and form cross-bridges.

With the help of ATP hydrolysis, myosin pulls the attached actin filaments and Z line towards the center of A band.

Consequently, the sarcomere shortens and results in contraction.