11.  If a woman ovulates two oocytes and both are fertilized,  
A.  identical twins result.
B.  fraternal twins result.
C.  Siamese twins result.
D.  monozygotic twinning occurs.
E.  paternal twins result.

12.  An embryonic cell that has the potential to develop into a wide range of tissues is called a/an  
A.  differentiated cell.
B.  multipotent cell.
C.  pluripotent cell.
D.  omnipotent cell.
E.  totipotent cell.

13.  An embryonic cell that contains the potential to give rise to any tissue type is called a/an  
A.  differentiated cell.
B.  multipotent cell.
C.  pluripotent cell.
D.  omnipotent cell.
E.  totipotent cell.

14.  Once the embryonic mass has 12 or more cells, it is called a  
A.  morula.
B.  gastrula.
C.  blastula.
D.  blastocyst.
E.  trophoblast.

15.  The single layer of cells that surrounds the blastocele is the  
A.  morula.
B.  gastrula.
C.  blastocyst.
D.  trophoblast.
E.  inner cell mass.

16.  When the embryonic mass of cells develops an internal cavity, the mass of cells is called a(n)  
A.  zygote.
B.  morula.
C.  blastocyst.
D.  embryonic disc.
E.  trophoblast.

17.  The inner cell mass of the blastocyst  
A.  consists of yolk-filled storage cells.
B.  contains cells that will form the embryo.
C.  represents the future placenta.
D.  will form the zona pellucida.
E.  contains cells that are discarded.

18. The placenta and membranes surrounding the embryo develop from the 
A. morula.
B. blastocyst.
C. trophoblast.
D. inner cell mass.
E. blastocele.

19.  At the time of implantation, the human embryo is in a stage of development known as the  
A.  fetus.
B.  zygote.
C.  morula.
D.  blastocyst.
E.  egg.

20.  The placenta plays an important role in  
A.  implantation.
B.  onset of lactation.
C.  beginning of parturition.
D.  provision of nutrients to the fetus.
E.  insulating the fetus.