forms from epiblast?

a. Chorion
b. Placenta
c. Amnion
d. Allantois

Asquirrel population lives in an area. over many years, a river in that area grows wider and stronger, eventually forming a canyon. the squirrel populations on the two sides of the canyon can no longer mate with each other and ultimately form distinct species. this is an example of

Most enzyme names end in the

What term describes a doctor who becomes a specialist by meeting standards beyond those of getting a license and passing a test in the specialty area?