Identical twins result from the fertilization of…….
a) one ovum by one sperm
b) one ovum by two sperms
c) two ova by two sperms
d) two ova by one sperm
Which of the following are mismatched?
a) endoderm: lining of the digestive tube
b) ectoderm: circulatory system
c) mesoderm: notochord
d) mesoderm: reproductive system
