#Question id: 18595
#Unit 11. Evolution and Behavior
#Question id: 5741
#Unit 8. Inheritance Biology
In a mammal 2 Barr bodies are observed. How many X chromosomes does the organism have?
#Question id: 23243
#Unit 13. Methods in Biology
#Question id: 7238
#Unit 5. Developmental Biology
Following
are the statements regarding to establishment of positive feedback loops for
limb bud formation.
A.
In the presumptive forelimb field, Tbx5 induces Wnt2b, which then upregulates
Fgf10, which in turn positively feeds back to maintain activation of both Wnt2b
and Tbx5.
B.
Mesodermal Fgf10 tells the surface ectoderm to continue to make Fgf8, and the
surface ectoderm continues to tell the underlying mesoderm to make Fgf10.
C.
Fgf10 provides the signal to initiate and propagate the limb-forming
interactions between ectoderm and mesoderm, and these signaling interactions
directly promote limb bud formation and growth.
D.
The Wnt protein acts through the canonical β-catenin pathway to induce Fgf8
expression in the ectoderm. This relay of signaling represents a foundational
stage in the formation of limb buds, because once Fgf8 is made in the surface
ectoderm, the surface ectoderm elongates to physically become the AER.
Which of the following statements correctly explained positive feedback loops during limb development?
#Question id: 12433
#Unit 10. Ecological Principles