11) During which stage of development do cells arrange themselves into three layers?

A) morula

B) cleavage

C) gastrulation

D) organogenesis

12) Which of the following is true of the animal pole of a zygote?

A) The animal pole is closer to the nucleus than the vegetal pole.

B) The animal pole is hollow.

C) The animal pole becomes the entire embryo.

D) The animal pole produces larger cells than the vegetal pole.

13) The blastocoel is:

A) a fertilized egg.

B) the group of cells that form the archenteron.

C) a fluid-filled cavity.

D) a hollow sphere of cells.

14) Migration of which of the following to different parts of the embryo produces various tissues and organs?

A) morula cells

B) the animal pole

C) the blastocoel

D) neural crest cells

E) notochord cells

15) Place the following steps of organogenesis in the correct order: (1) neural crest cells breakaway, (2) neural folds grow into a neural tube, (3) the notochord induces development of the neural plate.

A) 1, 2, 3

B) 1, 3, 2

C) 3, 1, 2

D) 2, 3, 1

E) 3, 2, 1

16) What is the effect of higher concentration of bicoid protein in part of a fruit fly embryo?

A) It will develop into the posterior end of the organism.

B) It will develop into the heart of the organism.

C) It will develop into the head end of the organism.

D) It lowers the chances of embryo survival.

17) A basic description of the function of morphogens is that they:

A) stimulate the formation of the ectoderm.

B) affect the course of local development.

C) kill cells during development.

D) stop all embryonic growth.

18) At which of the following levels does bicoid work in fruit flies?

A) regulation of development of the head end, middle, and posterior end

B) regulation of development of organ systems

C) regulation of development of organs only in the thorax region of the organism

D) regulation of development of wings

19) Which of the following is a process by which an initial set of genes turns on a second set of regulatory genes, which eventually turns on a third set of genes?

A) developmental chain reaction

B) gastrulation

C) the sonic hedgehog sequence

D) the genetic cascade

E) somite production

20) Which cells are most important in initiating the production of bicoid protein?

A) limb bud cells

B) posterior portion cells

C) nurse cells

D) neural tube cells