Deck 22: An Introduction to Animal Development

Question 1

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

A)increases;increases
B)increases;decreases
C)decreases;increases
D)decreases;decreases

Answer 1

C

Question 2

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?

A)the cortical granules of the sea urchin egg
B)the jelly layer of the sea urchin egg
C)the vitelline envelope of the sea urchin egg
D)the plasma membrane

Answer 2

C

Question 3

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

A)be able to fertilize the eggs normally
B)be able to fertilize eggs from other species
C)not be attracted to bind to the egg membrane
D)not be able to swim toward the egg

Answer 3

C

Question 4

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

A)Drosophila and Xenopus do not undergo gastrulation;humans do.
B)Drosophila and Xenopus undergo metamorphosis;humans do not.
C)Drosophila and Xenopus do not show development of germ layers;humans do.
D)In Drosophila and Xenopus the notochord remains;in humans,it disappears.
E)Drosophila and Xenopus do not undergo blastula formation;humans do.

Question 5

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

A)digestive
B)nervous
C)endocrine
D)circulatory
E)excretory

Question 6

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?

A)endodermal cells on the exterior of the embryo
B)mesodermal cells that develop on the inside of the blastocyst
C)ectodermal cells that line the inside of the blastocoel
D)endodermal cells that migrate to the inside of the blastocoel

Question 7

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?

A)neural tube
B)somites
C)digestive system
D)skin

Question 8

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

A)formation of three embryonic cell layers
B)movement and alignment of many embryonic cells
C)determination of cell types as a result of cell-cell interactions
D)formation of specialized plant tissues

Question 9

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?

A)formation of the neural tube
B)formation of the gastrula
C)formation of the notochord
D)formation of the somites
E)formation of the lateral mesoderm

Question 10

The cells of the somites are determined to become all of the following tissues except _____.

A)bone tissue
B)muscle tissue
C)nervous tissue
D)skin tissue
E)connective tissue

Question 11

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?

A)central nervous system
B)digestive system
C)kidneys
D)lungs

Question 12

What happens during gastrulation?

A)The neural tube forms.
B)The blastula forms.
C)The somites form.
D)The three embryonic tissue germ layers form.

Question 13

The function of the acrosomal complex during fertilization is _____.

A)to block polyspermy
B)to dissolve the coating of the egg
C)to nourish the sperm mitochondria
D)to permit maximum sperm motility

Question 14

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

A)tissue-specific proteins
B)bindin proteins
C)cytoplasmic determinants
D)mRNAs transcribed from embryonic genome

Question 15

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 _____.

A)acrosomal complexes in sperm
B)complex coverings of the egg
C)specific protein binding between sperm and egg
D)fertilization envelopes
E)blocking of non-species-specific mRNA sequences

Question 16

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?

A)organogenesis
B)cell differentiation
C)mitosis
D)morphogenesis
E)germ layer formation

Question 17

One difference between early development in humans and in Xenopus (frogs)is that _____.

A)in humans,there is no formation of the blastula;in Xenopus,the blastula is a critical stage in early embryogenesis
B)in humans,blastocysts implant into the uterine wall;there is no implantation in Xenopus
C)in humans,gastrulation is delayed as the egg moves along the fallopian tube;in Xenopus,gastrulation takes place immediately after blastula formation
D)in humans,the yolk sac is much smaller than that seen in Xenopus
E)in humans,neurulation occurs immediately after cleavage;in Xenopus,neurulation is delayed until after gastrulation

Question 18

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)_____.

A)structural protein retinal and/or lens cells
B)intercellular signal transmitted between retinal and lens cells
C)transcriptional factor that regulates genes involving retinal and/or lens cells
D)extracellular matrix protein secreted by the retinal and/or lens cells

Question 19

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?

A)0%
B)25%
C)50%
D)75%
E)100%

Question 20

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

A)Other kinds of signals serve similar functions in mammals.
B)Sperm-egg recognition relies on egg cytoplasmic components in mammals.
C)Sperm have evolved to become more selective in mammals.
D)Sea urchin fertilization occurs in open ocean.

Question 21

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

A)differentiation,pattern formation,morphogenesis,determination
B)differentiation,determination,morphogenesis,pattern formation
C)pattern formation,determination,morphogenesis,differentiation
D)pattern formation,morphogenesis,differentiation,determination
E)pattern formation,morphogenesis,determination,differentiation

Question 22

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

A)Somites are forming as distinct masses on either side of the neural tube.
B)Cells of the lateral mesoderm are undergoing rapid cell division.
C)Cells of the primitive retina are beginning to synthesize pigment molecules.
D)The embryo has developed a chambered heart.