Download Early Embryonic Development

Early Embryonic Development
1. Define zygote, embryology, and development.
2. Explain that the location of yolk in the zygote cytoplasm distinguishes the animal pole from the
vegetal pole.
3. Compare the appearance and contents of a starfish zygote to that of a frog zygote.
4. Explain the relationship between mitosis and cleavage, and how mitosis during embryonic
cleavage differs from regular cell division.
5. Describe the various stages of cleavage: zygote, inner cell mass, morula, blastula.
6. Describe how the amount of yolk in a zygote and developing embryo affects cell division,
resulting in blastomeres of different sizes in the developing embryo.
7. Compare and contrast cleavage patterns, and the resulting blastula formed, in the starfish
(which is the same as Sea Urchin) and the frog.
8. Explain how a blastocoel distinguishes a blastula from a morula.
9. Explain why the blastula circumference is essentially the same as the original zygote even
though the blastula is made up of many cells.
10. Explain the importance of both the cleavage stage and blastula formation to the developing
embryo.
11. Recognize that the inward movement of cells to create a blastopore marks the beginning of
gastrulation.
12. Differentiate between the blastocoel of the blastula and the archenteron of the gastrula.
13. Name the three germ layers of a gastrula - ectoderm, endoderm, and mesoderm - and name
the general tissues, organs and systems that develop from each layer.
14. Identify the location of the three germ layers in a starfish gastrula and a frog gastrula.
15. Describe the events that mark the beginning of organogenesis / differentiation in the frog
embryo: neurulation from the dorsal ectoderm and notochord development from the dorsal
mesoderm.
16. Explain how development following the gastrula stage involves differentiation and growth.
17. Sequence the series of events in frog development from fertilization to cleavage, through
gastrulation, and ending with neurulation and differentiation.
18. Explain how the heterogeneous nature of the zygote cytoplasm, and molecules like
transcription factors, can result in genes being "switched on" and "switched off" during the
process of organogenesis / differentiation.
19. Explain how embryonic induction uses "organizers" to direct development in other areas of
the embryo via chemical messages.
Patterns of Embryonic Development
1. Differentiate between external and internal embryonic development.
2. List the general requirements of an embryo for development.
3. Describe how the frog, as an example of an animal that exhibits external development in water,
meets the needs of the developing embryo.
4. Cite some reasons why external embryonic development on land is more difficult than in a
water environment.
5. Explain how internal fertilization and the amniotic egg are successful adaptations to external
embryonic development on land.
6. Differentiate between meroblastic cleavage, as exhibited by chicken embryos, and holoblastic
cleavage exhibited by starfish, frog and human embryos.
7. Describe the function of each of the extraembryonic membranes in the amniotic egg.
8. Differentiate between the general pattern of embryonic development in the three groups of
mammals: monotremes, marsupials, and placental mammals.