The ectoderm gives rise to A the lining of the digestive tra

The ectoderm gives rise to [A] the lining of the digestive tract, respiratory tract, pancreas, and liver. [B] the nervous system, including the eyes and ears. [C] structures derived from skin, such as hair, feathers, nails, or claws. [D] heart, blood vessels, muscle, and bones. [E] Both b and c The formation of the endoderm during gastrulation in frogs results from [A] movement of cells from the surface layer to the interior. [B] migration of cells within the blastocoel [C] formation of columnar cells at the vegetal pole. [D] rapid cell division. [E] migration of secondary mesenchyme cells. Which of the following statements about differential gene expression in segmentation is false [A] Maternal effect genes establish the polarity of the developing embryo. [B] The number, boundaries, and polarity of the larval segments are determined by proteins encoded by the segmentation genes. [C] Differences between the segments are mediated by head the activities of homeotic genes. [D] The mRNAs that are important in initial protein synthesis are made by embryonic transcription. [E] Segmentation genes include gap, pair rule, and segment polarity genes. Cortical results in the exposure of WNT RNA relative to inhibitors in the vegetal pole of Xenopus zygotes [A] inhibition [B] phosphorylation [C] degradation [D] rotation [E] determination Mutations in genes of the genes class often result in fly embryos that are missing every other segment [A] maternal effect [B] gap [C] pair rule [D] segment polarity [E] Hox

Solution

19. [E] both B and C

20. [A] Movement of the cells from the surface layer to the interior.

21. [B]

22. [A] Inhibition

23. [B] Gap Gene