An individual is born missing parts of the epidermal layer as well as hair. The
ID: 78839 • Letter: A
Question
An individual is born missing parts of the epidermal layer as well as hair. The problem began during development with which of these germ layers? [A] mesoderm [B] endoderm [C] ectoderm [D] none of the above [E] The pathway rescues catenin from degradation [A] shh [B] bicoid [C] fyn [D] wnt [E] erk2 Differentiation is caused by [A] loss of DNA [B] determination [C] morphogenesis [D] differential gene expression. [C] nuclear transplantation. Primary germ layer that gives rise to the lungs [A] medoderm [B] ectoderm [C] endoderm [D] blastoderm [E] none of the above In early embryonic development of the frog, the pieces of tissue that will form the backs of the eyes bulge from the growing brain. If one of these bits of tissue is removed and transplanted into the area that should become the frogs stomach, an eye develops there. This shows the importance of in embryonic development. [A] organogenesis [B] induction [C] differentiation [D] cleavage [E] The term "induction" describes a process in which a cell or group of cells [A] influences the development of another group of cells. [B] triggers the cell movements in an embryo. [C] stimulates the transcription of their own genes. [D] organizes the egg cytoplasm before fertilization. [E] inhibits the movement of the embryo.Explanation / Answer
Answer:
46). C. Ectoderm
Explanation:
The ectoderm generates the outer layer of the embryo, and it forms from the embryo's epiblast. The ectoderm develops into the surface ectoderm, neural crest, and the neural tube.
The surface ectoderm develops into: epidermis, hair, nails, lens of the eye, sebaceous glands, cornea, tooth enamel, the epithelium of the mouth and nose.
47). D. wnt
Explanation:
The Wnt/-catenin pathway is highly regulated to insure the correct temporal and spatial activation of its target genes. In the absence of a Wnt stimulus, the transcriptional coactivator -catenin is degraded by a multiprotein destruction complex.
48). D. Differential gene expression
Explanation:
Differentiation results from differential gene expression: The specific components of a given cell provides its special characteristics. These components are either synthesized by proteins, or are themselves proteins. By expressing different subsets of genes, two cells contain different subsets of gene products (proteins).
49. C. Endoderm
Explanation:
The endoderm forms: the stomach, the colon, the liver, the pancreas, the urinary bladder, the epithelial parts of trachea, the lungs, the pharynx, the thyroid, the parathyroid, and the intestines.
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