Question

question 8 of 10
what is the next step in muscle contraction after the actin changes shape?
a. myosin binds to actin.
b. an atp molecule binds to the myosin.
c. a calcium ion binds to actin.
d. myosin and actin slide past each other.

Explanation:

In muscle contraction, after actin changes shape (due to calcium binding), the next step is myosin binding to actin. This forms cross - bridges. Option B (ATP binding to myosin) occurs later (for myosin head detachment). Option C (calcium binding to actin) is the step that causes actin shape change (not after). Option D (sliding) happens after myosin - actin binding. So the correct next step is myosin binding to actin.

Answer:

A. Myosin binds to actin.