* not completed

. This chapter discusses the embryonic development of Drosophila melanogaster. How long does embryonic development take in this organism?

one hour correct incorrect

three hours correct incorrect

one day correct incorrect

ten days correct incorrect

* not completed

. The 'spinal cord' of Drosophila-its 'nerve cord'

consists of two parallel structures that run laterally, along the sides of the animal. correct incorrect

is in no way analogous to the spinal cord of vertebrates, since Drosophila has no spine! correct incorrect

runs along the dorsal side, opposite the mouth as is the case in vertebrates such as humans correct incorrect

runs along the ventral surface, on the same side as the mouth correct incorrect

* not completed

. The portion of the blastoderm-stage embryo which will give rise to most ectodermal, mesodermal, and endodermal tissues is called the:

germ band correct incorrect

imaginal discs correct incorrect

amnioserosa correct incorrect

germ line correct incorrect

* not completed

. The process of segmentation will form how many parasegments?

8 in the abdomen correct incorrect

11 to form the thorax and abdomen correct incorrect

14: 3 for the mouth, 3 in the thorax, and 8 in the abdomen correct incorrect

3: head, thorax, and abdomen correct incorrect

* not completed

. When do the legs and wings of a fly form?

during embryogenesis, after imaginal disc cells are segregated away at the cellular blastoderm stage correct incorrect

during pupation, from the imaginal discs correct incorrect

during the larval instars correct incorrect

legs and wings are present during larval stages, but take their final form only after metamorphosis correct incorrect

* not completed

. The portion of the Drosophila body plan which will produce the wing is called:

telson correct incorrect

abdomen correct incorrect

thorax correct incorrect

neuroectoderm correct incorrect

* not completed

. Maternal factors are

genes that control differentiation as a female or male fruit fly correct incorrect

proteins and mRNAs packaged into the egg by the mother correct incorrect

proteins and mRNAs that determine the organizing axes of the correct incorrect

substances present in the female that determine whether or not she will become a mother correct incorrect

* not completed

. Which protein (gene) functions to determine an anterior fate in the Drosophila embryo?

Bicoid correct incorrect

Caudal correct incorrect

Nanos correct incorrect

Torso correct incorrect

* not completed

. The development of the antero-posterior axis of Drosophila is initiated when:

the mother packages bicoid and nanos mRNA into the developing oocyte correct incorrect

the Toll receptor is activated after fertilization, leading to nuclear localization of Dorsal protein correct incorrect

the terminal group protein Torso sets up the anterior and posterior poles of the embryo correct incorrect

the sperm enters the micropyle at the anterior end, thus specifying the antero-posterior axis correct incorrect

* not completed

. Which is the correct hierarchy of gene activity in early Drosophila segmentation?

gap, segment polarity, pair-rule, maternal correct incorrect

maternal, gap, pair-rule, segment polarity correct incorrect

maternal, pair-rule, gap, segment-polarity correct incorrect

segment polarity, pair-rule, gap, maternal correct incorrect

* not completed

. Which would lead to a dorsalized embryo?

dorsal mutant correct incorrect

cactus mutant correct incorrect

Toll mutant correct incorrect

spätzle mutant correct incorrect

* not completed

. A gap-gene mutation could cause which of the following defects in the embryonic body plan?

every other segment is missing, resulting in T1, T3, A2, A4, etc., but no T2, A1, A3, and so on correct incorrect

patterning within each segment is abnormal, causing denticle belts to form across the entire segment correct incorrect

segments A2 through A6 are missing, but the rest of the pattern is essentially normal correct incorrect

the identity of one or more segments is transformed to that of a different segment correct incorrect

* not completed

. The activation of zygotic hunchback expression by Bicoid protein illustrates what principle in the establishment of positional information in embryos?

the mother can influence development through the packaging of materials into the egg correct incorrect

a gradient of a protein can activate a gene in a discrete region of an embryo through a threshold effect correct incorrect

the identity of segments in the embryo is a reflection of their position in the embryo correct incorrect

genes are activated or repressed by the binding of transcription factors to their regulatory regions correct incorrect

* not completed

. The adult body plan of the fly is based on reiterating structures called segments; segment precursors (parasegments) are first positioned at the cell-by-cell level by which group of genes?

maternal genes such as bicoid correct incorrect

gap genes such as Kruppel correct incorrect

pair-rule genes such as even-skipped correct incorrect

segmentation genes such as engrailed correct incorrect

* not completed

. engrailed expression defines the

anterior compartment of the segment correct incorrect

anterior margin of each segment correct incorrect

posterior compartment of the segment correct incorrect

posterior margin of each parasegment correct incorrect

* not completed

. Mutations in homeotic genes can lead to what type of developmental defect?

the anterior portion of the embryo does not develop correct incorrect

several adjacent segments will be missing from an otherwise intact embryo correct incorrect

segment and compartment boundaries will fail to form correct incorrect

the development of segments will be changed wholesale from their normal identity to that of a different segment correct incorrect

* not completed

. Which of the following, first discovered through mutagenesis studies in Drosophila, also function in the development of mammals like ourselves?

hedgehog correct incorrect

homeobox genes correct incorrect

the Wnt family correct incorrect

all of the options given are correct correct incorrect