Question 1

Which feature is characteristic of birds' but not placental mammals' embryonic development?

Accepted Answer

A)  The embryo forms from the epiblast. 
B)  Gastrulation occurs in the epiblast. 
C)  The hypoblast contributes to extraembryonic membranes. 
D)  Epiblast cells migrate through the primitive groove to become endoderm and mesoderm. 
E)  The blastocoel lies between the epiblast and hypoblast. 
A)  The embryo forms from the epiblast. 
B)  Gastrulation occurs in the epiblast. 
C)  The hypoblast contributes to extraembryonic membranes. 
D)  Epiblast cells migrate through the primitive groove to become endoderm and mesoderm. 
E)  The blastocoel lies between the epiblast and hypoblast. E

Question 2

Refer to the figure showing the expression of the Hoxb gene cluster in a mouse.   Based on the figure, you can conclude that

Accepted Answer

A)  determination of anterior structures is dependent upon expression of Hoxb1 and Hoxb2 genes. 
B)  Hoxb1 is expressed later in development than Hoxb9. 
C)  each Hoxb gene is expressed in a unique region along the anterior-posterior axis in which other Hoxb genes are not expressed. 
D)  there is greater Hoxb3 expression in the posterior than in the anterior region of the embryo. 
E)  Hoxb9 is the only Hoxb gene expressed in the anterior region of the embryo. 
A)  determination of anterior structures is dependent upon expression of Hoxb1 and Hoxb2 genes. 
B)  Hoxb1 is expressed later in development than Hoxb9. 
C)  each Hoxb gene is expressed in a unique region along the anterior-posterior axis in which other Hoxb genes are not expressed. 
D)  there is greater Hoxb3 expression in the posterior than in the anterior region of the embryo. 
E)  Hoxb9 is the only Hoxb gene expressed in the anterior region of the embryo. A

Question 3

Which statement about cleavage in placental mammals is true?

Accepted Answer

A)  The blastomeres divide synchronously. 
B)  Gene transcription occurs in blastomeres. 
C)  Cleavage occurs rapidly relative to other animals. 
D)  Cleavage is radial. 
E)  Cleavage is incomplete. 
A)  The blastomeres divide synchronously. 
B)  Gene transcription occurs in blastomeres. 
C)  Cleavage occurs rapidly relative to other animals. 
D)  Cleavage is radial. 
E)  Cleavage is incomplete. B

Question 4

Which statement about extraembryonic membranes of developing chicks is true?

Accepted Answer

A)  The allantoic membrane forms from endoderm and mesoderm, and it stores metabolic wastes. 
B)  The chorion and amnion form from endoderm and mesoderm. 
C)  The chorion secretes a protective fluid into the amniotic cavity. 
D)  The extraembryonic membrane closest to the eggshell is the amnion. 
E)  The chorion enhances water loss from the egg, keeping the embryo safe. 
A)  The allantoic membrane forms from endoderm and mesoderm, and it stores metabolic wastes. 
B)  The chorion and amnion form from endoderm and mesoderm. 
C)  The chorion secretes a protective fluid into the amniotic cavity. 
D)  The extraembryonic membrane closest to the eggshell is the amnion. 
E)  The chorion enhances water loss from the egg, keeping the embryo safe.

Question 5

Along the dorsal surface of the frog embryo, mesoderm cells secrete BMP proteins, which induce the overlying ectoderm to become epidermis.If the actions of BMP proteins were blocked,

Accepted Answer

A)  the ectoderm would develop into bone tissue. 
B)  the ectoderm would develop into neural tissue. 
C)  gastrulation would cease. 
D)  a second entire embryo would develop along the embryo's dorsal surface. 
E)  the ectoderm would develop into the lower skin layer (dermis). 
A)  the ectoderm would develop into bone tissue. 
B)  the ectoderm would develop into neural tissue. 
C)  gastrulation would cease. 
D)  a second entire embryo would develop along the embryo's dorsal surface. 
E)  the ectoderm would develop into the lower skin layer (dermis).

Question 6

If the placenta were to deteriorate during gestation, which process would be compromised?

Accepted Answer

A)  Cleavage in stages in the embryo 
B)  Gastrulation in the embryo 
C)  Implantation 
D)  Removal of urea and carbon dioxide from the embryo 
E)  Sloughing of the endometrium 
A)  Cleavage in stages in the embryo 
B)  Gastrulation in the embryo 
C)  Implantation 
D)  Removal of urea and carbon dioxide from the embryo 
E)  Sloughing of the endometrium

Question 7

Refer to the figure.   The gastrulation shown here is likely to be similar to gastrulation in a

Accepted Answer

A)  Xenopus (frog). 
B)  duck-billed platypus (monotreme). 
C)  human. 
D)  zebrafish. 
E)  sea urchin (echinoderm). 
A)  Xenopus (frog). 
B)  duck-billed platypus (monotreme). 
C)  human. 
D)  zebrafish. 
E)  sea urchin (echinoderm).

Question 8

In the chick embryo, which structure functions as the blastopore?

Accepted Answer

A)  Dorsal lip 
B)  Blastodisc 
C)  Primitive groove 
D)  Hypoblast 
E)  Blastocoel 
A)  Dorsal lip 
B)  Blastodisc 
C)  Primitive groove 
D)  Hypoblast 
E)  Blastocoel

Question 9

Which feature characterizes extraembryonic membranes of chicks and turtles, but not humans?

Accepted Answer

A)  They are part of the embryo. 
B)  They function in nutrition. 
C)  They are formed from contributions of ectoderm, endoderm, and mesoderm. 
D)  They function in storage of nitrogenous waste. 
E)  They function in gas exchange. 
A)  They are part of the embryo. 
B)  They function in nutrition. 
C)  They are formed from contributions of ectoderm, endoderm, and mesoderm. 
D)  They function in storage of nitrogenous waste. 
E)  They function in gas exchange.

Question 10

In which organism does the nuclear volume increase while the cytoplasmic volume stays the same during early cleavage?

Accepted Answer

A)  Fruit fly 
B)  Frog 
C)  Bird 
D)  Fish 
E)  Lizard 
A)  Fruit fly 
B)  Frog 
C)  Bird 
D)  Fish 
E)  Lizard

Question 11

As gastrulation begins, the cells of the chick embryo are organized as a

Accepted Answer

A)  blastocyst. 
B)  blastodisc. 
C)  hypoblast. 
D)  trophoblast. 
E)  yolk plug. 
A)  blastocyst. 
B)  blastodisc. 
C)  hypoblast. 
D)  trophoblast. 
E)  yolk plug.

Question 12

Amphibian gastrulation starts at the

Accepted Answer

A)  vegetal pole. 
B)  gray crescent. 
C)  animal pole. 
D)  archenteron. 
E)  blastocoel. 
A)  vegetal pole. 
B)  gray crescent. 
C)  animal pole. 
D)  archenteron. 
E)  blastocoel.

Question 13

Which feature characterizes the pole plasm of the Drosophila egg?

Accepted Answer

A)  It is located at both the animal and vegetal poles. 
B)  It surrounds nuclei as they migrate from the central region to the poles of the developing Drosophila. 
C)  It contains components necessary for differentiation into germ cells. 
D)  It is anchored to the poles of the embryo during gastrulation. 
E)  It lacks mitochondria and mRNA. 
A)  It is located at both the animal and vegetal poles. 
B)  It surrounds nuclei as they migrate from the central region to the poles of the developing Drosophila. 
C)  It contains components necessary for differentiation into germ cells. 
D)  It is anchored to the poles of the embryo during gastrulation. 
E)  It lacks mitochondria and mRNA.

Question 14

Which feature is a characteristic of both fruit flies and birds?

Accepted Answer

A)  Centrally located yolk in the egg 
B)  Migration of nuclei to the periphery of the egg 
C)  Incomplete cleavage 
D)  Larger blastomeres in the animal hemisphere than in the vegetal hemisphere 
E)  Cycles of mitosis without cell division 
A)  Centrally located yolk in the egg 
B)  Migration of nuclei to the periphery of the egg 
C)  Incomplete cleavage 
D)  Larger blastomeres in the animal hemisphere than in the vegetal hemisphere 
E)  Cycles of mitosis without cell division

Question 15

A researcher studying frog development finds that organizer cells in the anterior region of the embryo are inhibiting certain growth factors.When the researcher looks at the posterior region of the embryo, she is (likely/unlikely) _______ to find that the organizer cells are inhibiting these same growth factors.

Accepted Answer

The answer of A researcher studying frog development finds that...

Question 16

Refer to the figure showing two scanning electron micrographs of a chick embryo.Part A of the figure shows the embryo in cross section, and part B shows the embryo as you look down from above, with the overlying epidermal ectoderm removed.   In comparing these images, we can see that the structures labeled "a" and "b" in part B correspond to the structures labeled _______ in part A, respectively.

Accepted Answer

The answer of Refer to the figure showing two scanning...

Question 17

Which statement about frog eggs is true?

Accepted Answer

A)  Sperm-binding sites occur uniformly over the surface of the egg. 
B)  Microtubules organized by the sperm's centriole guide movements of cortical cytoplasm. 
C)  The gray crescent is a band of the most darkly pigmented cytoplasm in a fertilized frog egg. 
D)  Inner cytoplasm rotates, relative to cortical cytoplasm, toward the site of sperm entry. 
E)  The gray crescent marks the location of sperm entry. 
A)  Sperm-binding sites occur uniformly over the surface of the egg. 
B)  Microtubules organized by the sperm's centriole guide movements of cortical cytoplasm. 
C)  The gray crescent is a band of the most darkly pigmented cytoplasm in a fertilized frog egg. 
D)  Inner cytoplasm rotates, relative to cortical cytoplasm, toward the site of sperm entry. 
E)  The gray crescent marks the location of sperm entry.

Question 18

Choose the correct pairing of characteristics of the unfertilized frog egg and those of the fertilized frog egg.

Accepted Answer

A)  Bilaterally symmetrical: radially symmetrical 
B)  Gray crescent present: gray crescent absent 
C)  Diploid: haploid 
D)  β-catenin throughout the cytoplasm: β-catenin degraded in a certain region 
E)  Glycogen synthase kinase-3 (GSK-3) inhibited in a certain region: GSK-3 throughout the cytoplasm 
A)  Bilaterally symmetrical: radially symmetrical 
B)  Gray crescent present: gray crescent absent 
C)  Diploid: haploid 
D)  β-catenin throughout the cytoplasm: β-catenin degraded in a certain region 
E)  Glycogen synthase kinase-3 (GSK-3) inhibited in a certain region: GSK-3 throughout the cytoplasm

Question 19

You are watching the early cleavage stages in a sea urchin embryo and see that the first cleavage divides the egg in half and that the cleavage plane is parallel to the animal-vegetal axis.The second cleavage is also parallel to this axis, and the third cleavage is perpendicular to this axis.At this point, you are able to say that the embryo has a _______ cleavage pattern.

Accepted Answer

The answer of You are watching the early cleavage stages...

Question 20

Refer to the figure showing some of the manipulations carried out by Spemann on developing amphibians.   Experiment 1 resulted in

Accepted Answer

A)  two clumps of undifferentiated cells. 
B)  two normal embryos. 
C)  one normal embryo and one clump of undifferentiated cells. 
D)  two embryos joined at the belly. 
E)  two embryos joined along their backs. 
A)  two clumps of undifferentiated cells. 
B)  two normal embryos. 
C)  one normal embryo and one clump of undifferentiated cells. 
D)  two embryos joined at the belly. 
E)  two embryos joined along their backs.

Exam 43: Animal Development

Which feature is characteristic of birds' but not placental mammals' embryonic development?

Refer to the figure showing the expression of the Hoxb gene cluster in a mouse. Based on the figure, you can conclude that

Which statement about cleavage in placental mammals is true?

Which statement about extraembryonic membranes of developing chicks is true?

Along the dorsal surface of the frog embryo, mesoderm cells secrete BMP proteins, which induce the overlying ectoderm to become epidermis.If the actions of BMP proteins were blocked,

If the placenta were to deteriorate during gestation, which process would be compromised?

Refer to the figure. The gastrulation shown here is likely to be similar to gastrulation in a

In the chick embryo, which structure functions as the blastopore?

Which feature characterizes extraembryonic membranes of chicks and turtles, but not humans?

In which organism does the nuclear volume increase while the cytoplasmic volume stays the same during early cleavage?

As gastrulation begins, the cells of the chick embryo are organized as a

Amphibian gastrulation starts at the

Which feature characterizes the pole plasm of the Drosophila egg?

Which feature is a characteristic of both fruit flies and birds?

Which statement about frog eggs is true?

Choose the correct pairing of characteristics of the unfertilized frog egg and those of the fertilized frog egg.

Refer to the figure showing some of the manipulations carried out by Spemann on developing amphibians. Experiment 1 resulted in

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