#Question id: 7241
#Unit 5. Developmental Biology
If planaria are irradiated at a dosage that destroys nearly all neoblasts. Transplanting a single clonogenic neoblast in this planaria results:
#Question id: 7242
#Unit 5. Developmental Biology
The
cells of posterior marginal zone act as
the equivalent of the amphibian Nieuwkoop center because:
A.
once the PMZ has formed, it controls the other regions of the margin.
B.
Cells of PMZ initiate other regions of the margin from forming their own
primitive streaks.
C.
the entire marginal zone produces Wnt8c (capable of inducing the accumulation
of -catenin) and secrete Vg1, a member of the TGF-family.
D.
The PMZ cells secretes nodal protein and Nodal activity is needed to initiate
the primitive streak.
E.
When placed in the anterior region of the marginal zone, a graft of PMZ tissue
(posterior to and including Koller’s sickle) is able to induce wnt signaling.
Which of the following option is correct?
#Question id: 7243
#Unit 5. Developmental Biology
Match the following:
|
Column
I |
Column II |
|
A. Anterior necrotic zone |
I. Rapid apoptosis that occurs when
epithelial cells lose their attachment to the extracellular matrix. |
|
B. Anoikis |
II. Devoid of any neural innervation. |
|
C. Aneurogenic |
III. Mammalian equivalent to the chick
hypoblast and similar to the head portion of the amphibian organizer, it creates an
anterior region by secreting antagonists of Nodal. |
|
D. Anterior visceral endoderm |
IV. A zone of programmed cell death on the
anterior side of the developing tetrapod limb that helps shape the limb. |
#Question id: 7244
#Unit 5. Developmental Biology
Following statements are regarding to the evolutionary
conservation of homeotic gene organization and transcriptional expression in
fruit flies and mice.
A.
In fruit flies and mice genes with similar structures occupy the same relative
positions on each of the four chromosomes, and paralogous gene groups display
similar expression patterns.
B.
Hom-C cluster on Drosophila chromosome 3 and the four Hox gene clusters in the
mouse genome are similar and evolutionary conserved.
C.
Those mammalian genes homologous to the Drosophila labial, proboscipedia, and
deformed genes are expressed anteriorly and early, whereas those genes
homologous to the Drosophila AbdB gene are expressed posteriorly and later.
D.
In fruit flies and mice genes are orthologous Hox gene groups.
E.
Those mammalian genes homologous to the Drosophila labial, proboscipedia, and
deformed genes are expressed posteriorly and later, whereas those genes
homologous to the Drosophila AbdB gene are expressed anteriorly and early.
Which of the following combination is correct?
#Question id: 7245
#Unit 5. Developmental Biology
Gradients of Wnt are essential for normal regeneration of a head and a tail by planaria. Which one of the following statement is incorrect?
#Question id: 7246
#Unit 5. Developmental Biology
Treatment of Xenopus embryos with lithium dorsalizes the embryos by interfering with cell-cell signaling pathways. What, if anything, is the effect of lithium on hydra, and what might we infer about its mechanism of action?