#Question id: 7264
#Unit 5. Developmental Biology
The Dictyostelia social
amoebas are found in a wide range of soil habitats. They can come together to
form a fruiting structure, in which a proportion of cells are sacrificed to
build the stalk and the remainder differentiate into resilient dormant spores.
This multicellular life cycle is common to all Dictyostelids. It consists
of an interconnected programme of cell movement and cell differentiation, and
has been intensively studied in the model organism D. discoideum. Few mutants
(Column A) and phenotypes (Column B) are listed in the table given below.
|
Column A |
Column B |
|
A.
Loss of function of cAMP-dependent
protein kinase (PKA) |
i.
cell develop normally but unable to germinate |
|
B.
Loss of function of RegA |
ii.
Loose aggregate form |
|
C.
Loss of function of adenylate cyclase B |
iii.
No aggregation |
|
D.
Loss of function of gp80 |
iv.
accumulation of cAMP and PKA activation |
#Question id: 7265
#Unit 5. Developmental Biology
Following statement regarding to the cascade of regulated RNA splicing controls drosophila sexual differentiation.
A. The Sex-lethal (Sxl)
protein, encoded by the sex-lethal gene, is the first protein to act in the
cascade and present only in female embryos.
B. Early in development, the Sxl gene is transcribed from a
promoter that functions only in male embryos.
C. Later in development, this male-specific promoter is shut
off, and another promoter for sex-lethal becomes active in both male and female
embryos.
D. In male embryos, however, in the absence of early Sxl
protein, exon 3 of the sex-lethal pre-mRNA is spliced to exon 2 to produce an
mRNA that contains a stop codon early in the sequence.
Which of the following is correct?
#Question id: 7266
#Unit 5. Developmental Biology
After brief examination of the evolution of the tetrapod limb, from fish fins to human hands, has hopefully illuminated the importance of Hox gene regulation during limb development. Hox genes are critical for:
#Question id: 7267
#Unit 5. Developmental Biology
Endocrine disruptors can interfere with hormone function in many ways like, They can act as antagonists and inhibit the binding of a hormone to its receptor or block the synthesis of a hormone. which of the following example best explains the antagonistic effect of endocrine disruptors?
#Question id: 7268
#Unit 5. Developmental Biology
Match
the columns and choose the correct option.
|
Column
I |
Column
II |
|
A.
Progress zone |
i.
thickening of the ectoderm at the apex of the
developing limb bud |
|
B.
Apical ectodermal ridge |
ii.
The cells found within the most posterior region |
|
C.
Zone of polarizing activity |
iii.
The highly proliferative mesenchyme that fuels limb
bud growth |
#Question id: 7269
#Unit 5. Developmental Biology
Following statements are regarding to gastrulation in chick embryo.
A.
During gastrulation, future mesodermal and endodermal cells migrate from the
epiblast through the primitive streak into the interior of the blastoderm.
B.
An aggregation of cells, known as Hensen’s node, forms at the posterior end of
the streak.
C.
As the streak extends, cells of the epiblast move toward the primitive streak,
through it, and then outward again underneath the surface to give rise
internally to the mesoderm and endoderm, the latter displacing a lower layer of
cells called the endoblast.
D.
Cells that remain in the epiblast form the endoderm.
Which of the following statements are correct?