BIO351 Module 4 Exam with verified detailed solutions

BIO351 Module 4 Exam with |! |! |! |! |!




verified detailed solutions |! |!




Mesodermal cells at the site of the limb buds respond to beads soaked in
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FGF8 and grow out along the proximal-distal axis. If beads expressing FGF8
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are placed under the epithelium of the back there is no outgrowth. This
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experiment demonstrates which of the following?
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- Permissive induction
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- Proliferation
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- Competence
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- Gastrulation
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- Differentiation - Correct answer ✔- Competence
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LEC 1.3 Slide 6
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"Competence: a cell's ability to respond to an inductive signal."
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Think about this: the soaked Fgf8 beads are transplanted 'under the
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epithelium of the BACK ... [and] there is NO outgrowth."
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Because there is no outgrowth when this is translated, this means the cells of
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the back are not competent. Meaning, their signals are there/present from
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,Fgf8, however, the cell's (of the back) ability to comprehend and exact the
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goals of the Fgf8 signal is inadequate or incompetent.
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textbook:



Cells of the responding tissue must have both a receptor protein for the
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inducing factor and the ability to respond to the signal. The ability to receive
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and respond to a specific inductive signal is called competence (Waddington
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1940).



Researchers were examining the role of SHH on patterning the digits in the
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limb bud. They predict a gradient of SHH along the rostral/caudal axis is
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required to pattern the digits (left panel). Ablation of the Zone of Polarizing
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Activity (ZPA) lead to the SHH concentrations in the right panel. Based on
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this model, which pattern of digits (A-E) is expected.
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-C
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-D
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-E
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-A
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- B - Correct answer ✔- D
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LEC 1.3 Slides 14, 17-18
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As can be seen in the 'real' image (not depicted here), there are 2 thresholds
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for red, white, and blue for particular digits.
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, The gradient depicted is a straight, horizontal line quite low on the
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morphogen gradient. Because of this, red is the only color to be expressed.
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Somites are derived from which of the following embryonic tissues?
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- Endoderm
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- Presomitic mesoderm
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- Lateral plate mesoderm
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- Ectoderm - Correct answer ✔- Presomitic mesoderm
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LEC 1.4 Slide 14
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"Presomitic mesoderm generates somites-anlagen of the musculoskeletal
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system..."



LEC 4.2 Slide 5|! |! |!




"Somites segment from presomitic mesoderm."
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textbook:



When a somite is first separated from the presomitic mesoderm, all its cells
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are capable of becoming any of the somite-derived structures. As the somite
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