Devbiol Exams

• Which would most likely occur in the developing embryo if and when there was a default in the normal expression of the brachyury T gene?

  Malformation of lower vertebrae
• Which structure in avian and mammalian embryos function like the blastopore in amphibian embryo

  Primitive streak
• Which statement is true for neurulation?

  I. Neural tube separates from the epidermis and drop below surface

  II. Formation of neural tube is due to inductive influence of the chordamesoderm and/or notochordal plate

  III. Neural tube is derived from the endoderm

  IV. Microtubules play a role in neurulation

  V. During neurulation, mesodermal layer on either side of notochord splits into longitudinal divisions


  II. Formation of neural tube is due to inductive influence of the chordamesoderm and/or notochordal plate

  IV. Microtubules play a role in neurulation

  V. During neurulation, mesodermal layer on either side of notochord splits into longitudinal divisions
• Which of the following is not involved in left-right asymmetry of vertebrates:

  nodal
• Which of the following is a product of the 1st meiotic division?

  Secondary spermatocyte
• Which of the following genes is most likely inhibited in the case of error in the Anter-posterior axis establishment?

  O Nodal and Lefty

  O Pit2

  O Goosecoid but not Chordin and Noggin

  O Fgf8 and Nodal

  O Chordin but not BMP4

  Goosecoid but not Chordin and noggin
• Which of the following DOES NOT occur during cleavage


  Embryo grows significantly in mass
• Vitellogenic phase considers the change occurring in the cytoplasm

  True
• This involves the sequential expression of genes in the developing embryo to establish specialized cells. This is the concept of:

  Differentiation
• This has diploid set of chromosomes

  Intermediate spermatogonia
• The transition from maternal-to-zygotic genome activation is triggered ON by:

  new balance in the nuclear:cytoplasmicvolume ratio
• The transition from maternal to zygotic genome activation is triggered ON by the new balance in nuclear-cytoplasmic ratio

  True
• The transition from maternal to zygotic genome activation is triggered ON by the depletion of cyclin B and other cycling factors


  True
• The transition from maternal to zygotic genome activation is triggered ON by the addition of new gap phases in the tome cell cycle

  true
• The secreted factor ____ in coordination with OTX2, —

  cerberus
• The secreted factor ____ incoordination with OTX2, LIM1, and HESX1 genes are involved in establishing the cranial end of the embryo during gastrulation onwards to neurulation

  ● Lefty 2

  ● Nodal

  ● Brachury t gene

  ● Cerberus

  ● Sonic hedgehog

  ● Fgf8

  Cerberus
• The primitive streak develops from

  ● Body stalk

  ● Trophoblast

  ● Hypoblast

  ● Epiblast

  ● periblast

  epiblast
• The pairing of homologous chromosomes takes place during:

  Zygotene
• The onset of events like positional information, intracellular clock, and apoptosis illustrate the concept of:

  Inevitability
• The new balance in nuclear:cytoplasmic ratio that triggers the transition from maternal genome activation to zygotic genome activation happens during

  Early cleavage
• The localized formation of the blastopore is due to

  Invagination
• The initial dorsal-ventral axis in amphibian embryo is determined by

  Point of sperm entry
• The Hensen's node is homologous to the amphibian's:

  Dorsal lip of blastopore
• The formation of bilaminar and trilaminar disk is:

  Delamination
• The cortical reaction functions directly in the:

  Formation of fertilization membrane
• The commonality of having pharyngeal slits in the early embryonic development of vertebrates and the gradual differences there after illustrates the Law/ Theory of:

  ● Recapitulation

  ● Epigenesis

  ● Biogenesis

  ● Reformation

  Recapitulation
• The brain vesicle that will determine where cranial nerve will arise is the

  Metencephalon
• The archenteron of the developing frog embryo eventually develops into

  Digestive tract lumen
• The agent of ventral specification ofthe neural tube, probably originatingfrom the notochord is the __

  Sonic Hedgehog
• The actual fusion of the male and female perinuclei is homomixis

  False
• That of maternal genes and oocytecy to architecture-

  Preformed guidelines
• Stages of fertilization

  I. Onset of new DNA synthesis

  II. Cortical reaction

  III. First cell division

  IV. Acrosomal reaction; membrane depolarization

  Acrosomal reaction; membrane depolarization -> Cortical Reaction -> Fusion of Pronuclei -> onset of new DNA synthesis -> first cell division
• Stage of embryonic development characterized by the onset of morphogenetic movements and selective cell adhesions is the

  Gastrula
• Stage of embryonic development characterized by an increase in cell number in the absence of growth is the

  Cleavage
• Spreading of sheet of embryonic cells with accompanying interdigitation and intercalation

  Convergent extension
• Spermatogonia are:

  Self-Renewing
• Second meiotic arrest occurs

  Metaphase of meiosis
• Remarkably, Vg-1 and wnt are used in both frogs and chicks to establish a body axis, although in chicks this is the anteroposterior axis instead of the dorso-ventral axis. What is the region of the chick embryo that is thus analogous to the chordamesoderm?

  ● Koller's sickle

  ● Primitive streak

  ● Area pellucida

  ● Posterior marginal zone

  ● blastoderm

  Posterior Marginal Zone
• Regulating the development of the Cranio-caudal segments of the somites and the vertebrae in mammals is a function of

  Hox Genes
• Programmed cell death regulates proper structure sculpting by eliminating interdigital-webbings

  True