#Question id: 7166
#Unit 5. Developmental Biology
Just prior to the onset of gastrulation in an embryo, the "organizer" cells are specified. If you were to experimentally block the specification of these cells, what would you expect the result to be in the developing embryo?
#Question id: 7167
#Unit 5. Developmental Biology
The following
experiment is designed to study the role of several hormones in the regulation
of metamorphosis in frogs.
|
Group # |
Treatment |
Days
to Metamorphosis |
|
1 |
Saline |
30 |
|
2 |
Prolactin |
> 100 |
|
3 |
TSH |
15 |
|
4 |
Thyroxine |
10 |
|
5 |
Corticosterone |
30 |
|
6 |
Thyroxine
+ Corticosterone |
5 |
|
7 |
Prolactin + TSH |
30 |
|
8 |
Thyroid gland
removed |
> 100 |
These results suggest which of the following about prolactin (group 2 and group 7) at the dose tested?
#Question id: 7168
#Unit 5. Developmental Biology
Which one of the following
signaling pathways will best support the mediolateral intercalation in the
formation of the primitive streak in chick?
#Question id: 7169
#Unit 5. Developmental Biology
Before oogenesis begins, the oogonium divides four times with incomplete cytokinesis, giving rise to 16 interconnected cells in drosophila. These 16 germline cells, along with a surrounding epithelial layer of somatic follicle cells, constitute the egg chamber in which the oocyte will develop. These germline cells include:
#Question id: 7170
#Unit 5. Developmental Biology
Following statements
are regarding to maternally provided mRNAs—hunchback and caudal, are critical
for patterning the anterior and posterior regions of the body plan,
respectively.
A.
B. Translation of the
hunchback and caudal mRNAs is repressed by the diffusion gradients of Bicoid
and Nanos proteins, respectively.
C. Bicoid binds to a
specific region of caudal’s 3′UTR. Here, it binds Bin3, a protein that
stabilizes an inhibitory complex that prevents the binding of the mRNA 5′ cap
to the ribosome. By recruiting this translational inhibitor, Bicoid prevents
translation of caudal in the anterior of the embryo.
D.
Nanos protein prevents translation of the hunchback message. Nanos in the
posterior of the embryo forms a complex with several other ubiquitous proteins,
including Pumilio and Brat. This complex binds to the 3′UTR of the hunchback
message, where it recruits d4EHP and prevents the hunchback message from
attaching to ribosomes.
Which of the following statements are true?
#Question id: 7171
#Unit 5. Developmental Biology
Following statements are regarding to the early development in sea urchin.
A. most cells of the 16-cell embryo, the large micromeres are autonomously specified.
B. large micromeres inherit maternal determinants that were deposited at the vegetal pole of the egg; these become incorporated into the large micromeres at the fourth cleavage.
C. The conditionally specified large micromeres are now able to produce paracrine and juxtacrine factors that autonomously specify the fates of their neighbors.
D. Large micromeres become skeletogenic mesenchyme cells that will leave the blastula epithelium, enter the blastocoel, migrate to particular positions along the blastocoel wall, and then differentiate into the larval skeleton.
Which of the following statement is false?