What causes the myosin binding site of an actin molecule to be exposed?

ATP attaching to the myosin cross-bridge
A nerve impulse reaching the motor end plate of a motor nerve
Calcium ions attaching to troponin
Acetylcholine crossing the neuromuscular junction
Calcium ions attaching to troponin  Ca causes a change of shape to the troponin molecule when they attach. This causes troponin to wrench tropomyosin away from its resting position covering the binding site.

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Which of the following is the smallest unit in a muscle?
A. Muscle fibre
B. Myosin
C. Fasciculus
D. Myofibril
What structures attach a muscle to a bone?
A. A tendon
B. A fasciculus
C. A sarcomere
D. An internal intercostal
Which muscle is located on the posterior part of the forearm?
A. Flexor digitorum superficialis
B. Flexor digitorum profundus
C. Extensor digitorum
D. Triceps brachii
Which of the following muscles is NOT named after its location in the body?
A. Deltoid
B. Extensor carpi ulnaris
C. Rectus abdominis
D. Biceps femoris
Which of the following muscles IS named after its location in the body?
A. Sartorius
B. Triceps brachii
C. Soleus
D. Trapezius
Which is the correct equation for anaerobic respiration in humans?
A. Glucose + lactic acid โ†’ carbon dioxide + water
B. Glucose โ†’ lactic acid + carbon dioxide
C. Glucose โ†’ lactic acid + (little energy)
D. Glucoseโ†’ lactic acid
The part of a skeletal muscle cell that is able to contract is called
A. Sarcoplasm
B. Sarcolemma
C. Sarcomere
D. Sarcoplasmic reticulum

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