20. Development

Up to the eight-cell stage, the blastomeres of a mouse embryo can each form a complete embryo if isolated. This indicates that __________.

What primitive feature forms during gastrulation?

The primitive streak of a bird embryo is the functional equivalent of the __________ in a frog.

What is the embryonic origin of the lining of the digestive tube?

One difference between the blastula and gastrula stages of development is that __________.

Which of the following events occurs only during organogenesis?

In humans, the skeleton and muscles develop from the embryonic __________.

The human brain develops from __________.

Which of the following extraembryonic membranes functions in gas exchange and encloses a chamber for the deposition of wastes of a bird embryo?

In mammals, the __________ facilitates implantation in the uterine wall.

Evidence suggests that folic acid may help prevent the development of spina bifida, a common disabling birth defect. It is recommended that women increase their folic acid intake during pregnancy, especially in the first three months. Why is the timing of the folic acid intake relevant?

If you wanted to examine the extraembryonic membranes surrounding a lizard or mouse embryo, you would first have to cut through which of the following to see all the others?

During the development of most animals, cleavage leads to __________.

Which of the following correctly lists the embryonic stages in the order that they develop?

The cortical reaction of sea urchin eggs functions directly ina. the formation of a fertilization envelope.b. the production of a fast block to polyspermy.c. the generation of an electrical impulse by the egg.d. the fusion of egg and sperm nuclei.