20. Development

As an animal develops, organs form and the body transforms into a shape typical of the species in a process called __________.

People with Kartagener's syndrome suffer from a variety of ailments, including the intriguing condition known as situs inversus, a reversal of the abdominal and thoracic organs. This condition occurs because of __________.

The digits of a developing vertebrate limb respond to molecules that establish an anterior-posterior axis. These molecules originate in __________.

In an experiment on eye development, a thin piece of aluminum foil was placed between the bulging wall of the brain and the overlying ectoderm where the eye normally forms. Wherever the foil was placed, the lens failed to develop because the foil __________.

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?