#Question id: 7250
#Unit 5. Developmental Biology
Following
statements are regarding to signals that regulate axis extension in chick
embryos.
A.
In the stage 10 chick embryo, Fgf8 inhibits expression of the retinoic acid
(RA) synthesizing enzyme Raldh2 in the presomitic mesoderm and the expression
of the RA receptor RARβ in the neural ectoderm, thus preventing RA from
triggering differentiation in the caudal-lateral epiblast cells and the
caudal-most paraxial mesoderm.
B.
Fgf8 inhibits Sonic hedgehog (Shh) expression in the neural tube floorplate,
controlling the onset of ventral patterning genes.
C.
FGF signaling is also required for expression of Delta1 in the medial portion
of the caudal-lateral epiblast cells and promotes expression of Wnt8c.
D.
Fgf8 decays in the caudal paraxial mesoderm, Wnt signaling, most likely
provided by Wnt8c, now acts to promote Raldh2 in the adjacent paraxial mesoderm.
RA produced by Raldh2 activity expresses Fgf8 and Wnt8c.
Which of the following statements are correct?
#Question id: 17215
#Unit 7. System Physiology – Animal
#Question id: 734
#Unit 1. Molecules and their Interaction Relevant to Biology
Which of the following statements is true for two different tripeptides consisting of either glycine or proline?
#Question id: 29096
#Unit 8. Inheritance Biology
#Question id: 4785
#Unit 8. Inheritance Biology
One form of white eye is a recessive X-linked gene in Drosophila. From a mating of a heterozygous wild-type Drosophila female with a white-eyed male, what is the probability of wild type offspring?