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E55-2009 practice exam 3

Differentiation is a stable cellular state but recent

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______10. Differentiation is a ‘stable’ cellular state, but recent findings in the pancreas show that: A. direct transdifferentiation via ectopic gene expression is possible B. transdifferentiation can occur by niche signals C. transdifferentiation can occur by addition of stem cells to an organ D. non-pancreas cells can switch to pancreas cell types E. only stable genetic modification of cells can trigger transdifferentiation ______11. Regenerative abilities are greatest in which of the following animals: A. the mouse B. the zebrafish C. the frog D. the chick E. the planaria ______12. You overexpress Sox17 mRNA by microinjection into developing frog embryos, then perform RT-PCR on these embryos. You detect an elevation in the quantity of several endoderm-expressed genes. What does this result tell you? A. that Sox17 is necessary for endoderm development B. that Sox17 is sufficient for endoderm development C. that Sox17 is sufficient to convert non-endoderm cells to the endoderm fate D. that Sox17 is sufficient to upregulate endoderm genes in endoderm cells E. none of the above is accurate without additional data ______13. In chick embryos, we examined nested and abutting domains of Hox gene expression in the endoderm field after gastrulation. What does this observation tell us? A. that endoderm provides regional signals to the overlying mesoderm B. that a ‘pre-pattern’ exists in the endoderm C. it illustrates crosstalk between the mesoderm and endoderm D. that mesoderm provides regional signals to the underlying endoderm E. that ectoderm provides regional signals to the underlying endoderm ______14. The pancreatic buds receive inductive signals from: A. the notochord B. the vasculature C. the cardiogenic mesoderm D. the migrating primordial germ cells E. more than one answer is correct
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E-55, Exam 3-2009: Name Page 4 of 9 ______15. The definitive wave of blood formation, as opposed to the primitive wave, produces A. red blood cells B. endothelial cells C. white blood cells D. cardiogenic mesoderm E. both A and C ______16. The atrium chambers of the heart A. arise from cells in the most anterior region of the heart field B. arise from cells in the central region of the heart field C. arise from cells on the left side of the embryonic midline D. arise from cells in the most posterior region of the heart field E. arise from a population that is intermingled with future ventricle cells ______17. The program of endoderm specification is initiated by A. zygotic gene transcription B. inheritance of maternal factors C. the position of sperm entry into the egg D. targeted destruction of maternal factors in the egg’s animal hemisphere E. formation of the organizer ______18. Which statement is true about lateral plate mesoderm development in vertebrates? A. The heart forms from two initially separate primordia.
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