20. Development

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

How is the animal hemisphere of a frog blastula different from the vegetal hemisphere?

Which of the following describes the correct sequence of stages during embryogenesis?

How does a zygote differ from an ovum?

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

The development of a zygote into a blastula is called __________.

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

After a sperm penetrates an egg, a fertilization envelope forms. This envelope __________.

The period of repeated cell divisions without significant cell growth results in formation of the blastula and is called __________.

A sea urchin sperm penetrates the jelly coat of an egg and adheres to receptor proteins on the egg's surface as a result of __________.

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 __________.

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?

What primitive feature forms during gastrulation?

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

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