Question 1

The dorsal lip of the blastopore organizes embryo formation in frogs.The equivalent structure in chickens is _______.

Accepted Answer

The answer of The dorsal lip of the blastopore organizes...

Question 2

Spina bifida is a birth defect in humans in which part of the spinal cord, as well as the adjacent area of the spine, develops abnormally.What process was disturbed during prenatal development in individuals born with spina bifida?

Accepted Answer

Spina bifida is a neural tube

Question 3

If the dorsal lip of the blastopore is transplanted from one frog gastrula onto a second frog gastrula on the opposite side from the embryo's original blastopore, which result is the most likely?

Accepted Answer

A)  A belly piece will form. 
B)  Gastrulation will cease. 
C)  A second complete embryo will form belly-to-belly with the recipient of the transplant. 
D)  The transplant will be rejected. 
E)  Only half an embryo will develop at the site of transplantation. 
A)  A belly piece will form. 
B)  Gastrulation will cease. 
C)  A second complete embryo will form belly-to-belly with the recipient of the transplant. 
D)  The transplant will be rejected. 
E)  Only half an embryo will develop at the site of transplantation.

Question 4

Refer to the figure showing cytoplasmic factors in a fertilized frog egg.   Suppose a researcher experimenting with the frog egg shown in part A removes the vesicles containing the GSK-3 inhibiting protein.What will be the most likely result of this experiment?

Accepted Answer

A)  The embryo will develop into two larvae joined belly-to-belly. 
B)  No dorsal-ventral axis will be established in the embryo. 
C)  Anterior structures will form, but posterior structures will not form. 
D)  Two sets of dorsal structures will form. 
E)  An embryo with two dorsal-ventral axes will form. 
A)  The embryo will develop into two larvae joined belly-to-belly. 
B)  No dorsal-ventral axis will be established in the embryo. 
C)  Anterior structures will form, but posterior structures will not form. 
D)  Two sets of dorsal structures will form. 
E)  An embryo with two dorsal-ventral axes will form.

Question 5

Refer to the figure showing manipulations carried out by Spemann on developing amphibians.   The results of this experiment indicate that the gray crescent is _______ for normal development of the amphibian embryo.

Accepted Answer

The answer of Refer to the figure showing manipulations carried...

Question 6

Experimental destruction of cells of the hypoblast of a developing chick would most immediately impair

Accepted Answer

A)  formation of the primitive groove. 
B)  movement of surface cells into the gastrula. 
C)  cleavage. 
D)  formation of the blastocoel. 
E)  formation of extraembryonic membranes. 
A)  formation of the primitive groove. 
B)  movement of surface cells into the gastrula. 
C)  cleavage. 
D)  formation of the blastocoel. 
E)  formation of extraembryonic membranes.

Question 7

The mesoderm of the anterior part of a vertebrate embryo is programmed to produce forelegs rather than hind legs by

Accepted Answer

A)  convergent extension. 
B)  neural crest cells. 
C)  Hox genes. 
D)  the spacing of somites in the embryo. 
E)  the archenteron. 
A)  convergent extension. 
B)  neural crest cells. 
C)  Hox genes. 
D)  the spacing of somites in the embryo. 
E)  the archenteron.

Question 8

In placental mammals, implantation would fail if cells of the _______ failed to express adhesion molecules.

Accepted Answer

A)  inner cell mass 
B)  trophoblast 
C)  zona pellucida 
D)  embryonic ectoderm 
E)  placenta 
A)  inner cell mass 
B)  trophoblast 
C)  zona pellucida 
D)  embryonic ectoderm 
E)  placenta

Question 9

A body plan consisting of repeating segments that are modified during development into structures such as vertebrae, ribs, and muscles depends on the production of cells by

Accepted Answer

A)  the neural tube. 
B)  neural crest cells. 
C)  endoderm. 
D)  somites. 
E)  the notochord. 
A)  the neural tube. 
B)  neural crest cells. 
C)  endoderm. 
D)  somites. 
E)  the notochord.

Question 10

A woman ovulates two eggs that are fertilized by different sperm.The embryos implant and develop to full term.The two babies the woman gives birth to are

Accepted Answer

A)  identical twins, with identical genomes. 
B)  identical twins, sharing 50 percent of their genes. 
C)  non-identical twins, with no genes in common. 
D)  non-identical twins, with a 50 percent chance of being the same sex. 
E)  identical twins, with a 50 percent chance of being the same sex. 
A)  identical twins, with identical genomes. 
B)  identical twins, sharing 50 percent of their genes. 
C)  non-identical twins, with no genes in common. 
D)  non-identical twins, with a 50 percent chance of being the same sex. 
E)  identical twins, with a 50 percent chance of being the same sex.

Question 11

If you experimentally removed the GSK-inhibiting protein from a fertilized amphibian egg, a likely result would be

Accepted Answer

A)  more glycogen synthase kinase-3 (GSK-3) on the dorsal side than on the ventral side of the embryo. 
B)  more β-catenin on the ventral side than on the dorsal side of the embryo. 
C)  a redistribution of β-catenin to the dorsal side of the embryo. 
D)  an inversion of the anterior-posterior axis. 
E)  a disruption of the dorsal-ventral axis. 
A)  more glycogen synthase kinase-3 (GSK-3) on the dorsal side than on the ventral side of the embryo. 
B)  more β-catenin on the ventral side than on the dorsal side of the embryo. 
C)  a redistribution of β-catenin to the dorsal side of the embryo. 
D)  an inversion of the anterior-posterior axis. 
E)  a disruption of the dorsal-ventral axis.

Question 12

Epiboly

Accepted Answer

A)  is a form of convergent extension displayed during gastrulation. 
B)  occurs when a sheet of cells rolls inward to form an inner layer. 
C)  occurs when rows of cells move apart from one another. 
D)  is the process by which animal hemisphere cells flatten and spread toward the site of involution during frog gastrulation. 
E)  occurs when a sheet of cells bends inward. 
A)  is a form of convergent extension displayed during gastrulation. 
B)  occurs when a sheet of cells rolls inward to form an inner layer. 
C)  occurs when rows of cells move apart from one another. 
D)  is the process by which animal hemisphere cells flatten and spread toward the site of involution during frog gastrulation. 
E)  occurs when a sheet of cells bends inward.

Question 13

Which are least likely to be cytoplasmic determinants that direct embryonic development in frogs?

Accepted Answer

A)  Transcription factors 
B)  Protein kinases 
C)  Protein kinase inhibitors 
D)  Molecules of β-catenin 
E)  Ribosomal RNAs 
A)  Transcription factors 
B)  Protein kinases 
C)  Protein kinase inhibitors 
D)  Molecules of β-catenin 
E)  Ribosomal RNAs

Question 14

Experimental overexpression of β-catenin in another region of an amphibian embryo results in

Accepted Answer

A)  failure of cleavage to occur. 
B)  induction of a second axis of embryo formation. 
C)  failure of gastrulation to occur. 
D)  failure of invagination to occur. 
E)  speeding up of the cleavage process. 
A)  failure of cleavage to occur. 
B)  induction of a second axis of embryo formation. 
C)  failure of gastrulation to occur. 
D)  failure of invagination to occur. 
E)  speeding up of the cleavage process.

Question 15

Which feature characterizes the chick gastrula?

Accepted Answer

A)  It is a round ball of cells with a central cavity. 
B)  The blastocoel is located between the epiblast and the hypoblast. 
C)  The hypoblast does not contribute to the extraembryonic membranes. 
D)  The hypoblast is located above the epiblast. 
E)  The embryo proper develops from the hypoblast. 
A)  It is a round ball of cells with a central cavity. 
B)  The blastocoel is located between the epiblast and the hypoblast. 
C)  The hypoblast does not contribute to the extraembryonic membranes. 
D)  The hypoblast is located above the epiblast. 
E)  The embryo proper develops from the hypoblast.

Question 16

Which feature characterizes the trophoblast?

Accepted Answer

A)  Trophoblast cells adhere to each other but lack adhesion molecules on their exposed surfaces. 
B)  The trophoblast digests its way into the endometrium until it is fully embedded in the uterine wall. 
C)  The trophoblast is the last extraembryonic membrane to form in placental mammals. 
D)  Trophoblast cells use proteolytic enzymes secreted by the inner cell mass. 
E)  The trophoblast surrounds the zona pellucida. 
A)  Trophoblast cells adhere to each other but lack adhesion molecules on their exposed surfaces. 
B)  The trophoblast digests its way into the endometrium until it is fully embedded in the uterine wall. 
C)  The trophoblast is the last extraembryonic membrane to form in placental mammals. 
D)  Trophoblast cells use proteolytic enzymes secreted by the inner cell mass. 
E)  The trophoblast surrounds the zona pellucida.

Question 17

The mammalian blastocyst differs from a frog blastula in that the mammalian blastocyst

Accepted Answer

A)  lacks a blastocoel. 
B)  is produced via cleavage. 
C)  forms after a solid ball of cells has formed. 
D)  produces both the embryo and support structures, such as the embryonic side of the placenta. 
E)  lacks blastomeres. 
A)  lacks a blastocoel. 
B)  is produced via cleavage. 
C)  forms after a solid ball of cells has formed. 
D)  produces both the embryo and support structures, such as the embryonic side of the placenta. 
E)  lacks blastomeres.

Question 18

Which feature characterizes complete cleavage?

Accepted Answer

A)  It occurs in eggs with large amounts of yolk. 
B)  In frogs, it results in smaller cells in the vegetal hemisphere. 
C)  Divisions create a disc of small cells sitting on an undivided yolk mass. 
D)  Cells with more yolk are larger than those with less yolk. 
E)  It is characteristic of chick eggs. 
A)  It occurs in eggs with large amounts of yolk. 
B)  In frogs, it results in smaller cells in the vegetal hemisphere. 
C)  Divisions create a disc of small cells sitting on an undivided yolk mass. 
D)  Cells with more yolk are larger than those with less yolk. 
E)  It is characteristic of chick eggs.

Question 19

Which feature characterizes cleavage in most animals?

Accepted Answer

A)  Rapid replication of DNA 
B)  Meiosis 
C)  Growth of cells 
D)  Extensive gene expression 
E)  Extensive translation of gene transcripts 
A)  Rapid replication of DNA 
B)  Meiosis 
C)  Growth of cells 
D)  Extensive gene expression 
E)  Extensive translation of gene transcripts

Question 20

A researcher who wants to block initiation of the cytoplasmic reorganization that is revealed by the appearance of the gray crescent in a developing frog should block the actions of

Accepted Answer

A)  mitochondria contributed by the egg. 
B)  GSK-3. 
C)  the centriole contributed by the sperm. 
D)  β-catenin. 
E)  GSK-inhibiting protein. 
A)  mitochondria contributed by the egg. 
B)  GSK-3. 
C)  the centriole contributed by the sperm. 
D)  β-catenin. 
E)  GSK-inhibiting protein.

Exam 43: Animal Development

The dorsal lip of the blastopore organizes embryo formation in frogs.The equivalent structure in chickens is _______.

Spina bifida is a birth defect in humans in which part of the spinal cord, as well as the adjacent area of the spine, develops abnormally.What process was disturbed during prenatal development in individuals born with spina bifida?

If the dorsal lip of the blastopore is transplanted from one frog gastrula onto a second frog gastrula on the opposite side from the embryo's original blastopore, which result is the most likely?

Refer to the figure showing cytoplasmic factors in a fertilized frog egg. Suppose a researcher experimenting with the frog egg shown in part A removes the vesicles containing the GSK-3 inhibiting protein.What will be the most likely result of this experiment?

Refer to the figure showing manipulations carried out by Spemann on developing amphibians. The results of this experiment indicate that the gray crescent is _______ for normal development of the amphibian embryo.

Experimental destruction of cells of the hypoblast of a developing chick would most immediately impair

The mesoderm of the anterior part of a vertebrate embryo is programmed to produce forelegs rather than hind legs by

In placental mammals, implantation would fail if cells of the _______ failed to express adhesion molecules.

A body plan consisting of repeating segments that are modified during development into structures such as vertebrae, ribs, and muscles depends on the production of cells by

A woman ovulates two eggs that are fertilized by different sperm.The embryos implant and develop to full term.The two babies the woman gives birth to are

If you experimentally removed the GSK-inhibiting protein from a fertilized amphibian egg, a likely result would be

Epiboly

Which are least likely to be cytoplasmic determinants that direct embryonic development in frogs?

Experimental overexpression of β-catenin in another region of an amphibian embryo results in

Which feature characterizes the chick gastrula?

Which feature characterizes the trophoblast?

The mammalian blastocyst differs from a frog blastula in that the mammalian blastocyst

Which feature characterizes complete cleavage?

Which feature characterizes cleavage in most animals?

A researcher who wants to block initiation of the cytoplasmic reorganization that is revealed by the appearance of the gray crescent in a developing frog should block the actions of

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