Question

during a muscle contraction, calcium ions bind to tropomyosin, and this exposes binding sites for attachment of myosin cross bridges to actin.
a true
b false

Explanation:

During muscle contraction, calcium ions bind to troponin, not tropomyosin. When calcium binds to troponin, it causes a conformational change that moves tropomyosin away from the myosin - binding sites on actin. This allows myosin cross - bridges to attach to actin.

Answer:

B. False