A critical early step in development is the establishment of positional information in the embryo. The local concentration of substances called _________ in the embryo helps impart this information.

Morphogens work by bringing about the production of the proteins called _______, which turn _______ on or off.

Development works from the general to the specific. In Drosophila, the morphogen called bicoid operates early in development by specifying the development of _______ and _______ portions of the embryo.

In animal development, the process of cleavage produces a ball of cells with an interior cavity. In the succeeding evelopmental process, called gastrulation, the cells in the embryo migrate to form three layers of cells, the _______, _______, and _______, which in terms of location are the _______, _______, and ________ layers of cells in the organism.

In vertebrates, a support structure called a notochord serves to _______, or bring about, the development of a structure called the neural tube, which gives rise to both the _______ and _______.

In what way is development a good example of a biological process that is self-regulating?

In what order do the following developmental steps occur?

a. organogenesis

b. fertilization

c. blastula formation

d. morula formation

e. gastrulation

The process of gastrulation involves;

a. massive cell death.

b. little or no growth of the embryo.

c. development of three tissue layers.

d. organogenesis.

e. cell enlargement.

Organogenesis is accomplished, in part, by the ability of some cells to bring about developmental change in other cells. This process is referred to as:

a. reduction.

b. transformation.

c. translation.

d. induction.

e. fusion.

The cells that migrate from the developing neural tube and eventually form different organs and tissues throughout the body are:

a. neural crest cells.

b. archenteron cells.

c. mesenchyme cells.

d. stem cells.

e. endoderm cells.