1. A sarcomere
is a section of a myofibril.
gets shorter when it contracts.
has striations.
All of the choices are correct.

2. During muscular contraction
actin and myosin filaments slide past each other.
ATP supplies energy. 
calcium ions (Ca++) are involved.
all of the above

3. At a neuromuscular junction, 
a nerve impulse causes the release of a neurotransmitter.
a neurotransmitter causes calcium to be released into the muscle cell. 
A & B
none of the above

4. Which is NOT a function of muscles?
cause movement
produce heat
absorb nutrients
maintain posture

5. A skeletal muscle cell
has light and dark bands (striations).
has only one nucleus.
is under involuntary control.
None of the above are true

6. The origin of the biceps brachii is 
the attachment of the muscle that remains relatively fixed during contraction. 
the scapula.
proximal radius.
A & B

7. The stages in muscle contraction include a
nerve impulse reaching a neuromuscular junction.
nerve impulse stimulating the release of calcium ions.
actin filaments sliding past myosin filaments. 
all the above are true

8. The functional unit of a muscle fiber is the 
sarcomere.
myofilament.
myofibril.
neuromuscular junction.

9. Which of the following statements is NOT true about muscle activity. 
Muscles can only pull, they never push.
All muscles have at least two attachments: the origin and insertion.
During contraction, the muscle origin moves toward the insertion.
All muscles cross at least one joint.

10. Muscle fatigue is due, in part, to the accumulation of
lactic acid.
citric acid.
ATP.
ACTH.