Embryology

53. Bicoid was the first morphogen discovered. What makes it an atypical morphogen?

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שאלה #182912

		A. It is a transcription factor, NOT a signaling molecule
		B. It forms a gradient
		C. It obeys the “French flag” model
		D. It diffuses between nuclei in a syncytium
		E. A+D
		F. B+C

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54. Which model predicted the mechanism of vertebrate segmentation before its discovery?

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שאלה #182914

		The French flag model
		The Waddington landscape
		The clock and wavefront model
		The Salami model
		The Baguette model

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55. Vertebrate segmentation involves:

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שאלה #182915

		An oscillatory expression of genes
		Several stages each with unique genes, each dependent on the previous
		Simultaneous segmentation of the entire mesoderm
		Induction of somite segmentation by neural crest

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56. Which statement about segmentation is correct?

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שאלה #182916

		Developed only once in and is preserved in evolution
		Developed once but gradually changed
		Developed independently in early and advanced vertebrates
		Developed independently in vertebrates and invertebrates

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60. The “new head” hypothesis:

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שאלה #182917

		Is a theory of how development of primitive chordates into vertebrates involved development of sensory organs from neural crest and placodes
		Is a new theory of how the head developed in primitive chordates by secondary neurulation
		Is a theory of how primary neurulation led to development of the jaws
		Is a theory of how advanced vertebrates developed sophisticated brains which come from neural placodes

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61. Which factor is NOT involved in development of the neural tube?

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שאלה #182918

		Sonic hedgehog (Shh)
		Wnt signal
		Sox2 transcription factor
		MyoD transcription factor

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62. What is a special trait of neural crest differentiation?

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שאלה #182919

		Allows the development of a sophisticated brain
		The only cell type that can migrate
		Forms many tissues, typical of both ectoderm and mesoderm
		Develops into only a single type of cell (monopotent)

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63. In two different pregnancies with monozygotic twins, doctors detected only one amnion in one pregnancy and two in the other. Which is true?

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שאלה #182920

		Twins sharing a single amnion separated earlier than twins with two amnions
		The number of chorions, NOT amnions is relevant for separation time
		Twins with a single amnion separated later than twins with two amnions
		It’s hard to distinguish between monozygotic twins with one amnion and dizygotic twins

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64. Potential uses of chimeras in research and medicine include:

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שאלה #182922

		Distinguishing intrinsic and extrinsic functions of genes by comparing full mutants to mutant/wild-type chimeras
		Implanting tissues between embryos from closely related species to determine the origin of specific tissues
		Potentially growing organs in animals for human transplantation
		All of the above

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65. In the field of stem cell derived embryo models (SEMs), what is the difference between blastoids and ETX embryos?

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שאלה #182923

		Blastoids are derived from embryonic and extraembryonic stem cells and model post- implantation stages, while ETX embryos model only the blastocyst stage.
		ETX embryos are assembled from embryonic stem cells (ESCs), trophoblast stem cells (TSCs), and extraembryonic endoderm (XEN) cells to model early post-implantation development, while blastoids mimic the structure and lineage composition of the blastocyst.
		Both blastoids and ETX embryos originate from somatic cell nuclear transfer and are used to model human implantation stages
		Blastoids are created from germ cells and model gastrulation, while ETX embryos are generated from stem cells and model late implantation

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Discuss, Learn and be Happy דיון בשאלות

53. Bicoid was the first morphogen discovered. What makes it an atypical morphogen?

54. Which model predicted the mechanism of vertebrate segmentation before its discovery?

55. Vertebrate segmentation involves:

56. Which statement about segmentation is correct?

60. The “new head” hypothesis:

61. Which factor is NOT involved in development of the neural tube?

62. What is a special trait of neural crest differentiation?

63. In two different pregnancies with monozygotic twins, doctors detected only one amnion in one pregnancy and two in the other. Which is true?

64. Potential uses of chimeras in research and medicine include:

65. In the field of stem cell derived embryo models (SEMs), what is the difference between blastoids and ETX embryos?

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