Internal organs develop from which germ layer?
a. the endoderm
b. the mesoderm
c. the ectoderm
d. the blastoderm
Question 2
A muscle relaxes after contracting when
a. calcium is taken up by internal organelles.
b. internal acetylcholine is broken apart by acetylcholinesteras e.
c. troponin is taken up by internal organelles.
d. myosin and actin begin to interact.