20. Development

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

Which stage of development is common in amphibians but not seen in mammals?

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

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 __________.

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.

Which of the following is common to the development of both birds and mammals?a. holoblastic cleavageb. epiblast and hypoblastc. trophoblastd. gray crescent

The archenteron develops intoa. the mesoderm.b. the endoderm.c. the placenta.d. the lumen of the digestive tract.

What structural adaptation in chickens allows them to lay their eggs in arid environments rather than in water?a. extraembryonic membranesb. yolkc. cleavaged. gastrulation