J.F. Barresi; Scott F. Gilbert
The bicoid protein gradient results from: - ANSWER: the diffusion of bicoid protein
across the syncytial embryo
. Which of the following is true about maternal effect genes such as bicoid -
ANSWER: embryo maternal mRNA genotype is same as mother genotype
The bicoid gradient is not representative of morphogen gradients observed in -
ANSWER: The bicoid gradient is not representative of morphogen gradients
observed in
How does the mother place bicoid and nanos mRNAs at opposing ends of the
drosophila oocyte? - ANSWER: bicoid mRNA is transported to the anterior end along
microtubules
Which of the following is true about dorsal-ventral patterning in the drosophila
oocyte? - ANSWER: SOG antagonizes Dpp signaling
Which of the following is NOT true about gap gene expression: - ANSWER: it may be
inhibited by pair-rule genes
Each stripe of pair-rule gene expression is activated by: - ANSWER: b. its own
enhancer
c. transcriptional activators and repressors
e. b and c
Which of the following supports the position of Hunchback (Hb) upstream of the
gap gene Kruppel (Kr) and downstream of Bicoid (Bcd) during drosophila early
development? - ANSWER: all of the above
Which of these homeotic transformations may result from a Hox gene mutation? -
ANSWER: arm into leg
Which of these propositions is consistent with spatiotemporal colinearity of Hox
genes? (hint: Hox gene number reflects order on chromosome) - ANSWER: c and d
c. hoxa1 is expressed before hoxa3
d. hoxa1 is expressed more anteriorly than hoxa3
Which of the following is NOT true about gastrulation? - ANSWER: c. mesoderm
stays outside
, Which of the following is true about gastrulation? - ANSWER: c. cells passing through
the blastopore first end up most anterior
Which of the following is NOT true about the blastopore? - ANSWER: its initial
position indicates the ventral side of the embryo
Which of the following is NOT true about embryonic tissues? - ANSWER:
mesenchymal cells are arranged as a sheet
Which of the following is NOT true about the cytoskeleton? - ANSWER: .
microtubules growth can be bidirectional
Which of the following is true? - ANSWER: radial cell-cell intercalations contribute to
epiboly
Which of the following is true about specification of the germ layers? - ANSWER:
Sox17 specifies the endoderm fate
Which of the following is true about specification of the dorsal-ventral axis in
the frog embryo? - ANSWER: B-catenin is a transcription factor that activates dorsal
fates
Which of the following describe the requirements for Nieuwkoop center
formation: - ANSWER: a. nuclear B-catenin
b. VegT
Which of the following describe the requirements for Spemann organizer
formation: - ANSWER: a. nuclear B-catenin
c. reception of Nodal-related ligands (Vg1 and Xnr)
e. a and c
Vertebrate embryos develop following which of the following stage orders -
ANSWER: fertilization, cleavage, gastrulation, organogenesis
Which of the following statements describing the relationship between cell
commitment and cell totipotency is WRONG : - ANSWER: committment is an abrupt
process that takes place just prior to differentiation
Which of the following factors may disrupt embryonic development ? - ANSWER: a.
aneuploidy
b. DNA mutations
c. teratogens
d. all of the above
Which type of mutations change the encoded amino acid sequence - ANSWER:
nonsense
b. missense