#Question id: 7203
#Unit 5. Developmental Biology
Following statements are given regarding to the genes in Drosophila.
A. The anterior posterior compartment of each segment of drosophila is regulated by the expression of engrailed and wingless genes.
B. The gap genes are activated or repressed by the maternal effect genes, and are expressed in one or two broad domains along the anterior-posterior axis.
C. The transcription patterns of the anterior gap genes are initiated by the different concentrations of the Hunchback and Bicoid proteins.
D. The segment polarity genes encode proteins that are constituents of the delta-notch and Hedgehog signaling pathways.
E. After the segmental boundaries are set, the pair-rule and gap genes interact to regulate the homeotic selector genes, which specify the characteristic structures of each segment.
Which one of following option has all the correct statements?
#Question id: 7204
#Unit 5. Developmental Biology
Following statements are regarding to anterior-posterior polarity in planaria.
A. The anterior expression of Notum functions to antagonize the posteriorly produced Wnt, leading to head specification.
B. Regulation of the balance between Wnt and Notum signals may underlie not only head-tail specification but also regulation of organ size.
C. In addition, there appears to be an anterior-to-posterior gradient of Erk signaling that functions as a positive inducer of tail specification.
D. Wnt signaling achieves its repression of head regeneration by inhibiting Erk. Therefore, only in those more anterior regions lacking Wnt (due to Notum’s repression of Wnt) can Erk induce head regeneration.
Which of the following statements are incorrect?
#Question id: 7205
#Unit 5. Developmental Biology
In cloning experiments on the frog xenopus laevis, nuclei were removed from intestinal cells of tadpoles and transplanted into zygotes whose nuclei had been removed. A small percent of these zygotes developed into normal frogs, suggesting that
#Question id: 7206
#Unit 5. Developmental Biology
Which of the following statements explains the dominant mutation of Pmar1 results in a vegetalized embryo is due to:
#Question id: 7207
#Unit 5. Developmental Biology
Which of the following statements is true about formation of the primitive streak ?
A. by the cellular dance mechanism, the cells came down the sides of the epiblast to undergo a medially directed intercalation of cells in the posterior margin where primitive streak forms.
B. Cellular dance is mediated by wnt planar cell polarity pathway in the hypoblast cells, at the posterior edge of the embryo.
C. The Wnt pathway activated by fibroblast growth factors (FGFs) produced by the hypoblast.
D. The Wnt planar cell polarity pathway activated by b-catenin produced by the epiblast.
#Question id: 7208
#Unit 5. Developmental Biology
Following statements are given about cleavage in drosophila.
A. During the ninth division cycle, approximately five nuclei reach the surface of the anterior pole of the embryo. These nuclei become enclosed by cell membranes and generate the pole cells that give rise to the gametes of the adult.
B. During tenth division of cycle, the other nuclei migrate to the cortex (periphery) of the egg and at this stage, embryo is called a syncytial blastoderm .
C. When the nuclei reach the periphery of the egg during the tenth cleavage cycle, each nucleus becomes surrounded by microtubules and microfilaments. The nuclei and their associated cytoplasmic islands are called transmembrane.
D. Following division cycle 13, the cell membrane (which had covered the egg) folds inward between the nuclei, eventually partitioning off each energid into a single cell. This process creates the cellular blastoderm.
Which of the following combination are correct?