#Question id: 7219
#Unit 5. Developmental Biology
Following statements are regarding to the role of the Disheveled and β-catenin proteins in specifying the cells of the sea urchin embryo.
A. During normal development, β-catenin accumulates predominantly in the micromeres and somewhat less in the veg2 tier cells.
B. In embryos treated with lithium chloride, β-catenin accumulates in the nuclei of all blastula cells and the cells of the animal pole become specified as ectoderm.
C. When β-catenin is prevented from entering the nuclei (i.e., it remains in the cytoplasm), the vegetal cell fates are not specified, and the entire embryo develops as a ciliated ectodermal ball.
D. When β-catenin is prevented from entering the nuclei (i.e., it remains in the cytoplasm), the vegetal cell fates are specified, and the entire embryo specified as endoderm and mesoderm .
Which of the following statements are true?
#Question id: 7220
#Unit 5. Developmental Biology
The anterior-posterior polarity of the drosophila embryo is established while the oocyte is still in the egg chamber, and it involves interactions between the developing egg cell and the follicular cells that enclose it. Following are certain statements:
A. The gurken message appears to be synthesized in the oocyte, and it is transported into the nurse cells. Here it becomes localized between the nucleus of nurse cells and the cell membrane, and it is translated into Gurken protein.
B. Gurken signal is received by the follicle cells at that position through a receptor protein encoded by the torpedo gene.
C. This signal results in the “posterior -anteriorization” of these follicle cells.
D. Posterior follicle cells signals to recruit Par-1 protein organizes microtubules specifically with their minus (cap) and plus (growing) ends at the anterior and posterior ends of the oocyte, respectively.
E. The motor protein kinesin, is an ATPase that will use the energy of ATP to transport material to the plus end of the microtubule. Dynein, however, is a “minus-directed” motor protein that transports its cargo in opposite direction.
F. These zygotic messengers bicoid and nanos mRNAs are carried by motor proteins along the microtubules to the anterior and posterior ends of the oocyte, respectively.
Which combination of the above statements are correct?
#Question id: 7221
#Unit 5. Developmental Biology
The cells of the neural plate are characterized by expression of the Sox family of transcription factors (Sox1, 2, and 3). These factors-
#Question id: 7222
#Unit 5. Developmental Biology
During development of sea urchin, The fates of the different cell layers are determined by which process?
#Question id: 7223
#Unit 5. Developmental Biology
In drosophila, the dorso-ventral axis of the embryo becomes divided into four regions early in embryogenesis.
A. The ventral mesoderm, which will form muscles and other internal connective tissues
B. The amnioserosa, which gives rise to an extra-embryonic membrane on the dorsal side of the embryo
C. The dorsal ectoderm, which gives rise to larval epidermis
D. The ventral ectoderm or neuroectoderm, which gives rise to the larval nervous system and epidermis
What is the correct sequence of these regions from ventral to dorsal?
#Question id: 7224
#Unit 5. Developmental Biology
Following statements are given regarding to the migration through primitive streak in chick.
A. Cells migrate to the primitive streak, and as they enter the embryo, the deep-moving cells give rise to the endodermal organs of the embryo, as well as to most of the extraembryonic membranes.
B. The migration of mesodermal cells through the anterior primitive streak and their condensation to form the chordamesoderm also appear to be controlled by FGF and Wnt signalling.
C. Wnt is expressed in the primitive streak and repels migrating cells away from the streak.
D. Once cells migrate away from the streak, further movement of the mesodermal precursors appears to be regulated by FGF8 proteins.
Which of the following statement is incorrect?