Exam 22: An Introduction to Animal Development

What would be one clue that you are observing cell differentiation in a frog embryo?

The mammalian zona pellucida is digested during the process of fertilization.This structure is probably most similar to which of the follwong structures of sea urchin eggs?

What is a major difference between the development of Drosophila or Xenopus (frogs)and that of humans?

During organogenesis,the first organ system to begin forming in animal embryos is the _____ system.

Scientists using RNA in situ hybridization techniques observed that a transcription factor called macho-1 localized to some cells during early cleavage,but not others.Descendents of these cells expressing macho-1 produce mesodermal tissues.If you prevented the expression of macho-1 in an embryo during cleavage,which structures might you expect to be absent in later development?

Which of the following is the most basic process in the developing embryo because all of the other processes listed can occur only after it,or in conjunction with it?

What happens during gastrulation?

During gastrulation in amphibians,the presumptive mesoderm moves into the interior of the embryo by following fibrils of fibronectin.Given what you know about gastrulation,you predict that the fibronectin is most likely secreted by which cells?

The function of the acrosomal complex during fertilization is _____.

During cleavage the size of individual cells _____,while the overall size of the embryo _____.

Spina bifida is one of the most prevalent of human birth defects.The defect usually involves the spinal cord or the spinal canal opening to the outside of the body.In severe cases,movement of the legs may be limited or entirely absent.At which stage of development is this defect likely to occur?

In many animal embryos,the eye develops very early.The Pax6 protein is important to eye development;its absence can prevent the formation of eyes in mice and humans.Thus,Pax6 probably acts as a(n)_____.

Many amphibian species release their sperm and eggs directly into a watery environment.All of the following mechanisms might ensure species-specific fertilization in these populations except _____.

Which of the following directors of embryonic development can be found within unfertilized eggs?

Gastrulation is an important event in early embryonic development.Which of the following is Not a result of this process?

Chordin is an organizer protein found only in the dorsal regions of frog embryos.Removing chordin would most likely disrupt the determination of which structure?

Suppose an antibody to bindin was introduced into a chamber containing sea urchin sperm and eggs.You predict that the antibody-treated sperm will _____.

Sperm-egg interactions are species-specific in sea urchins,but not in mammals.What might be one reason for this difference?

Which of the following is the correct sequence in the development of specialized cells?

The allele D codes for right-handed coiling in a species of snail,while allele d codes for left-handed coiling.Assuming the proteins encoded by these two alleles are cytoplasmic determinants,if a dd female mates with a DD male,what percentage of offspring snails will develop shells that are left-handed coils?