* not completed

. The segmental identity of imaginal discs is determined by:

Hox genes correct incorrect

gap genes correct incorrect

segment polarity genes correct incorrect

maternal genes correct incorrect

* not completed

. In thinking about the development of the wing imaginal disc of Drosophila, what is the significance of "compartments"?

A compartment is a signaling center that controls antero-posterior patterning correct incorrect

Compartments are developmental units, in that the wing forms from the "wing compartment" correct incorrect

Compartments are epithelial sacs, set aside during embryogenesis, that will give rise to adult structures such as wings after metamorphosis. correct incorrect

Since cells in adjacent compartments have different lineage histories, adjacent compartments can adopt different fates and differentiation patterns, as in the formation of the anterior and posterior portions of the wing blade. correct incorrect

* not completed

. Hedgehog signaling at the compartment boundary in the Drosophila wing disc leads to the expression of which signaling molecule in the adjacent anterior cells?

Engrailed correct incorrect

Wingless correct incorrect

Decapentaplegic correct incorrect

Sonic hedgehog correct incorrect

* not completed

. Keeping in mind the fact that genes are often named for the phenotype of a mutation in that gene, what might be the phenotype of a mutation of the Distal-less gene in Drosophila?

Mutations of distal-less would fail to pattern the wing veins along their antero-posterior axis correct incorrect

Distal-less mutants would form only distal structures, like the tarsus (distal end) of the legs without a coxa (proximal end). correct incorrect

Distal-less mutants would form only proximal structures, like the coxa (proximal end) of the legs without a tarsus (distal end). correct incorrect

Mutants in distal-less would have altered patterns of gene expression throughout the leg disc. correct incorrect

* not completed

. Which of the following correctly describes the sequence of events by which the position of limbs along the antero-posterior axis of chick and mouse embryos is specified?

Hox gene expression in the mesoderm activates expression of limb-specific genes, which turn on FGF expression and formation of the limb buds. correct incorrect

Wnt signaling activates Hox gene expression, which turns on FGF expression and formation of the limb buds. correct incorrect

FGF expression in the mesoderm activates Wnt signaling, which turns on expression of limb-specific genes and formation of the limb buds. correct incorrect

Hox gene expression in the mesoderm activates FGF signaling, which turns on Wnt expression and formation of the limb buds. correct incorrect

* not completed

. Cartilage (bone-forming tissue) and connective tissue of the vertebrate limb originate from

mesodermal cells that migrate into the limb bud from the somites correct incorrect

mesodermal mesenchyme of the limb bud correct incorrect

the apical ectodermal ridge correct incorrect

the progress zone correct incorrect

* not completed

. Removal of the apical ectodermal ridge of a limb bud leads to

continued development of the proximal structures, but no formation of new distal structures correct incorrect

degeneration of the limb bud correct incorrect

regeneration of a new apical ridge from adjacent epidermal tissue correct incorrect

regeneration of the entire limb bud from underlying mesoderm correct incorrect

* not completed

. Grafting of a second polarizing region into the anterior region of a limb bud results in

formation of additional digits in mirror symmetry with the normal digits correct incorrect

formation of a second limb bud at the site of the graft correct incorrect

formation of new digits that lack any specific identity correct incorrect

formation of new digits, but only those of anterior identity correct incorrect

* not completed

. Which of the following proteins is unlikely to be involved in pre-axial polydactyly in mice?

Sonic hedgehog correct incorrect

Gli transcription factors correct incorrect

Delta correct incorrect

Patched 1 correct incorrect

* not completed

. The Drosophila apterous gene is related to the mouse Lmx1b gene, and both are involved in

controlling segmentation along the antero-posterior axis correct incorrect

determining whether or not wings are made correct incorrect

specifying dorsal identity in their respective appendages correct incorrect

specifying what structure is made from a given segment correct incorrect

* not completed

. The muscle-forming cells of the vertebrate limb come from

the ectodermal epithelium of the limb bud correct incorrect

the mesodermal mesenchyme of the limb bud, derived from lateral plate ectoderm correct incorrect

mesodermal cells that migrate into the limb bud from the somites correct incorrect

the progress zone correct incorrect

* not completed

. If apoptosis in the developing limb were blocked, what feature of a normal limb would not form?

The bones and muscles would not form. correct incorrect

The overlying epidermis would not form. correct incorrect

All the bones would form as the same structure. correct incorrect

The digits would not be separated. correct incorrect

* not completed

. The programmed cell death that separates the digits depends on which signaling pathway?

BMP correct incorrect

FGF correct incorrect

Shh correct incorrect

Wnt correct incorrect

* not completed

. The type of tooth that will form in different regions of the jaw is controlled by

BMP expression correct incorrect

homeobox gene expression correct incorrect

lateral inhibition correct incorrect

previous patterning in the mesoderm correct incorrect

* not completed

. Heart development begins as

a folding process in the mesoderm below the notochord that is exactly like neural tube formation. correct incorrect

an outgrowth of the endoderm above the gut that forms a tube that will become the heart. correct incorrect

a pair of tubes in the lateral plate mesoderm that fuse together along the midline to form a single tube that will become the heart. correct incorrect

a mesenchymal condensation below the notochord that forms the heart tube. correct incorrect

* not completed

. The engineered expression of the mouse Pax6 gene in the Drosophila antennal disc

has no effect, because mouse genes cannot work in insects correct incorrect

can cause formation of mouse-type eye structures on the antenna correct incorrect

will transform the antenna disc into a wing disc correct incorrect

can cause formation of Drosophila eye structures on the antenna correct incorrect