1. Which germ layers are present at the end of
week 3 of development (day 21)?
(A) Epiblast only
(B) Epiblast and hypoblast
(C) Ectoderm and endoderm
(D) Ectoderm, mesoderm, and endoderm
(E) Epiblast, mesoderm, and hypoblast
2. Which process establishes the three
definitive
germ layers?
(A) Neurulation
(B) Gastrulation
(C) Craniocaudal folding
(D) Lateral folding
(E) Angiogenesis
3. The first indication of gastrulation in the
embryo is
(A) formation of the primitive streak
(B) formation of the notochord
(C) formation of the neural tube
(D) formation of extraembryonic mesoderm
(E) formation of tertiary chorionic villi