Question 1

Which of the following terms is inclusive of the others?

Accepted Answer

A)  Organogenesis 
B)  Neurulation 
C)  Morphogenesis 
D)  Cellular differentiation 
E)  None of the answers are correct 
A)  Organogenesis 
B)  Neurulation 
C)  Morphogenesis 
D)  Cellular differentiation 
E)  None of the answers are correct A

Question 2

The following groups of mutants developed from mutations in genes active during the development of Drosophila. Based on the characteristics of the mutants, which group resulted from mutations in the earliest-acting gene?

Accepted Answer

A)  Mutants with half the normal number of body segments 
B)  Mutants in which cells that would normally become epidermal cells developed into nerve cells 
C)  Mutants that have kinky bristles instead of the long, curled bristles of normal flies 
D)  Mutants without body segments 
E)  Mutants with tail structures at both ends 
A)  Mutants with half the normal number of body segments 
B)  Mutants in which cells that would normally become epidermal cells developed into nerve cells 
C)  Mutants that have kinky bristles instead of the long, curled bristles of normal flies 
D)  Mutants without body segments 
E)  Mutants with tail structures at both ends B

Question 3

When cells cease dividing during development, they are

Accepted Answer

A)  terminally differentiated. 
B)  stem cells. 
C)  undergoing apoptosis. 
D)  pluripotent. 
E)  embryonic. 
A)  terminally differentiated. 
B)  stem cells. 
C)  undergoing apoptosis. 
D)  pluripotent. 
E)  embryonic. A

Question 4

Mutations in maternal-effect genes are readily identified because

Accepted Answer

A)  heterozygous mutant individuals are produced from homozygous mutant mothers. 
B)  homozygous mutant individuals from heterozygous parents can develop, but eggs laid by homozygous mutant females cannot develop. 
C)  heterozygous mutant individuals from homozygous parents can only develop normally if the mother is homozygous mutant. 
D)  heterozygous mutant females produce eggs that are not capable of normal development. 
E)  homozygous mutant individuals do not develop and are embryonic lethal. 
A)  heterozygous mutant individuals are produced from homozygous mutant mothers. 
B)  homozygous mutant individuals from heterozygous parents can develop, but eggs laid by homozygous mutant females cannot develop. 
C)  heterozygous mutant individuals from homozygous parents can only develop normally if the mother is homozygous mutant. 
D)  heterozygous mutant females produce eggs that are not capable of normal development. 
E)  homozygous mutant individuals do not develop and are embryonic lethal.

Question 5

Transcription factors are

Accepted Answer

A)  mRNA products of maternal genes that are transcribed during oogenesis and translated after fertilisation. 
B)  cytoplasmic determinants that are transcribed in the zygote and segregated into particular blastomeres during cleavage. 
C)  proteins that regulate the transcription of other genes during development. 
D)  genes that control the expression of other genes. 
E)  All of the answers are transcription factors. 
A)  mRNA products of maternal genes that are transcribed during oogenesis and translated after fertilisation. 
B)  cytoplasmic determinants that are transcribed in the zygote and segregated into particular blastomeres during cleavage. 
C)  proteins that regulate the transcription of other genes during development. 
D)  genes that control the expression of other genes. 
E)  All of the answers are transcription factors.

Question 6

In Drosophila, a bicoid egg

Accepted Answer

A)  will develop into a larva with two heads. 
B)  will develop into an adult without a head or a thorax. 
C)  will develop into an embryo without a head or thorax region. 
D)  has two nuclei. 
E)  will not develop into a syncytium. 
A)  will develop into a larva with two heads. 
B)  will develop into an adult without a head or a thorax. 
C)  will develop into an embryo without a head or thorax region. 
D)  has two nuclei. 
E)  will not develop into a syncytium.

Question 7

Of the main processes in embryogenesis, which begins first?

Accepted Answer

A)  Cell differentiation 
B)  Cell proliferation 
C)  Cell migration 
D)  Morphogenesis 
E)  Programmed cell death 
A)  Cell differentiation 
B)  Cell proliferation 
C)  Cell migration 
D)  Morphogenesis 
E)  Programmed cell death

Question 8

Genomic equivalence is exhibited when all

Accepted Answer

A)  genes in an organism are equal. 
B)  cells in an organism have the same genome. 
C)  cell lineages in an organism show similar loss of genetic information during development. 
D)  All of the answers are correct. 
E)  None of the answers are correct. 
A)  genes in an organism are equal. 
B)  cells in an organism have the same genome. 
C)  cell lineages in an organism show similar loss of genetic information during development. 
D)  All of the answers are correct. 
E)  None of the answers are correct.

Question 9

You observe an animal embryo that is spherical in shape. Transverse sections through the embryo show that the outer wall consists of three layers of cells, and that there is a single axis of symmetry. The interior of the embryo is a fluid-filled cavity. The most recent developmental process to affect this embryo directly was

Accepted Answer

A)  organogenesis. 
B)  gastrulation. 
C)  cleavage. 
D)  morphogenesis. 
E)  neurulation. 
A)  organogenesis. 
B)  gastrulation. 
C)  cleavage. 
D)  morphogenesis. 
E)  neurulation.

Question 10

Developmental regulatory molecules that act in a concentration-dependent fashion are called

Accepted Answer

A)  anterior determinants. 
B)  ligands. 
C)  homeodomain proteins. 
D)  morphogens. 
E)  polarity genes. 
A)  anterior determinants. 
B)  ligands. 
C)  homeodomain proteins. 
D)  morphogens. 
E)  polarity genes.

Question 11

In a cross between a female Drosophila homozygous for a recessive mutant maternal-effect gene (m-/m-) and a wild-type male (m+/m+), the percentage of progeny that show normal development will be

Accepted Answer

A)  0 per cent. 
B)  25 per cent. 
C)  50 per cent. 
D)  75 per cent. 
E)  100 per cent. 
A)  0 per cent. 
B)  25 per cent. 
C)  50 per cent. 
D)  75 per cent. 
E)  100 per cent.

Question 12

Mammalian embryos can develop normally despite having some blastomeres removed during early cleavage because

Accepted Answer

A)  in the development of mammals, intercellular signalling is of more importance than cytoplasmic signalling. 
B)  maternal factors present within the zygote have no influence on the development of mammalian embryos. 
C)  cell-cell signalling does not become important in mammalian development until after the formation of the blastula. 
D)  mammalian blastomeres remain unipotent throughout the early stages of cleavage. 
E)  embryonic stem cells are pluripotent. 
A)  in the development of mammals, intercellular signalling is of more importance than cytoplasmic signalling. 
B)  maternal factors present within the zygote have no influence on the development of mammalian embryos. 
C)  cell-cell signalling does not become important in mammalian development until after the formation of the blastula. 
D)  mammalian blastomeres remain unipotent throughout the early stages of cleavage. 
E)  embryonic stem cells are pluripotent.

Question 13

Which of the following statements about early development in marsupials is CORRECT?

Accepted Answer

A)  The eggs of marsupials are virtually yolk-free, so the blastomeres are all of a similar size. 
B)  The tissues of the embryo proper are derived from a specific set of blastomeres, clustered together to form an inner cell mass, at one end of the blastula. 
C)  The first cleavage division is vertical, but the second cleavage division is horizontal in one blastomere and vertical in the other. 
D)  The egg is surrounded by external envelopes, which are porous to uterine secretions that nourish the embryo until it implants. 
E)  The egg is yolk rich and the first three divisions are unequal. 
A)  The eggs of marsupials are virtually yolk-free, so the blastomeres are all of a similar size. 
B)  The tissues of the embryo proper are derived from a specific set of blastomeres, clustered together to form an inner cell mass, at one end of the blastula. 
C)  The first cleavage division is vertical, but the second cleavage division is horizontal in one blastomere and vertical in the other. 
D)  The egg is surrounded by external envelopes, which are porous to uterine secretions that nourish the embryo until it implants. 
E)  The egg is yolk rich and the first three divisions are unequal.

Question 14

With regard to animal development, what is a somite?

Accepted Answer

A)  Segmentally random blocks of mesoderm situated in the centre of a fully developed neural tube 
B)  All of the options listed are incorrect 
C)  Repeated subunits of the dermomyotome 
D)  A partially differentiated region of sclerotome 
E)  Alpha-linked 1-3-$\beta$-arabinoxylans that arise around the margins of a developing neural plate 
A)  Segmentally random blocks of mesoderm situated in the centre of a fully developed neural tube 
B)  All of the options listed are incorrect 
C)  Repeated subunits of the dermomyotome 
D)  A partially differentiated region of sclerotome 
E)  Alpha-linked 1-3-$\beta$-arabinoxylans that arise around the margins of a developing neural plate

Question 15

In animal development, zygotic genes

Accepted Answer

A)  belong to the egg nucleus. 
B)  belong to the sperm nucleus. 
C)  are part of the zygote genome. 
D)  are found in the cytoplasm of the zygote. 
E)  are inherited only from the mother. 
A)  belong to the egg nucleus. 
B)  belong to the sperm nucleus. 
C)  are part of the zygote genome. 
D)  are found in the cytoplasm of the zygote. 
E)  are inherited only from the mother.

Question 16

During gastrulation, three different cell layers become apparent. One of these is the ectoderm (ecto = outer, dermis = skin). Immediately within the ectoderm is the mesoderm. As ecto = outer, and endo = inner, what would be the term given to the cell layer folded within the invaginating vegetal plate?

Accepted Answer

A)  Endocarp 
B)  Endoderm 
C)  Endoform 
D)  Endochyma 
E)  All of the options listed are incorrect 
A)  Endocarp 
B)  Endoderm 
C)  Endoform 
D)  Endochyma 
E)  All of the options listed are incorrect

Question 17

A stem cell that can give rise to only one type of differentiated cell is called unipotent. By an extension of this nomenclature logic, what would be the term given to a stem cell that can give rise to many cell types?

Accepted Answer

A)  Bipotent 
B)  Alphapotent 
C)  Radial-potent 
D)  Megapotent 
E)  Multipotent 
A)  Bipotent 
B)  Alphapotent 
C)  Radial-potent 
D)  Megapotent 
E)  Multipotent

Question 18

You are listening to a debate on the processes of neurulation in mammals compared to fishes. Both speakers agree that in fish, neurulation involves cells from either side of the midline coming together completely to form a seam, as opposed to most other vertebrates whereby two neural folds rise upwards on either side of a neural groove and then fold towards each other and meet to form a tube. Speaker one asserts that in fish, because of the morphology of the resulting structure, this processes produces a 'neural keel', whereas speaker two states that this process results in a 'neural tube'. Which speaker, if any, is correct?

Accepted Answer

A)  Neither, neurulation in fish at this developmental stage produces a neural plate 
B)  Neither, neurulation in fish at this developmental stage produces a neural groove 
C)  They are both correct - either term is acceptable 
D)  Speaker one 
E)  Speaker two 
A)  Neither, neurulation in fish at this developmental stage produces a neural plate 
B)  Neither, neurulation in fish at this developmental stage produces a neural groove 
C)  They are both correct - either term is acceptable 
D)  Speaker one 
E)  Speaker two

Question 19

During cleavage, cell division is rapid because

Accepted Answer

A)  cells undergo mitosis without any intervening synthesis of DNA. 
B)  the G1 and G2 phases of the cell cycle may be virtually eliminated. 
C)  the S phase is reduced in time. 
D)  components of the spindle are more rapidly synthesised. 
E)  the presence of yolk speeds up cytokinesis. 
A)  cells undergo mitosis without any intervening synthesis of DNA. 
B)  the G1 and G2 phases of the cell cycle may be virtually eliminated. 
C)  the S phase is reduced in time. 
D)  components of the spindle are more rapidly synthesised. 
E)  the presence of yolk speeds up cytokinesis.

Question 20

Which of the following mutant Drosophila phenotypes resulted from a mutation in a maternal gene?

Accepted Answer

A)  An embryo with half the normal number of body segments 
B)  An embryo that lacks several abdominal segments 
C)  An embryo without head segments 
D)  Mutants with antennae attached to the posterior 
E)  An embryo with a pair of legs instead of antennae attached to the head 
A)  An embryo with half the normal number of body segments 
B)  An embryo that lacks several abdominal segments 
C)  An embryo without head segments 
D)  Mutants with antennae attached to the posterior 
E)  An embryo with a pair of legs instead of antennae attached to the head

Exam 21: Animal Development

Which of the following terms is inclusive of the others?

The following groups of mutants developed from mutations in genes active during the development of Drosophila. Based on the characteristics of the mutants, which group resulted from mutations in the earliest-acting gene?

When cells cease dividing during development, they are

Mutations in maternal-effect genes are readily identified because

Transcription factors are

In Drosophila, a bicoid egg

Of the main processes in embryogenesis, which begins first?

Genomic equivalence is exhibited when all

Developmental regulatory molecules that act in a concentration-dependent fashion are called

In a cross between a female Drosophila homozygous for a recessive mutant maternal-effect gene (m-/m-) and a wild-type male (m+/m+), the percentage of progeny that show normal development will be

Mammalian embryos can develop normally despite having some blastomeres removed during early cleavage because

Which of the following statements about early development in marsupials is CORRECT?

With regard to animal development, what is a somite?

In animal development, zygotic genes

A stem cell that can give rise to only one type of differentiated cell is called unipotent. By an extension of this nomenclature logic, what would be the term given to a stem cell that can give rise to many cell types?

During cleavage, cell division is rapid because

Which of the following mutant Drosophila phenotypes resulted from a mutation in a maternal gene?

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In a cross between a female Drosophila homozygous for a recessive mutant maternal-effect gene (m^-/m^-) and a wild-type male (m⁺/m⁺), the percentage of progeny that show normal development will be