![]() Chordata Arthropoda Annelida Echinodermata Mollusca Nematoda Rotifera Platyhelminthes Cnidaria PoriferaSTANDARDS:a. Use specific examples from the tree in your discussion. Explain how each of these pairs of features was important in constructing the phylogenetic tree shown below. (1) Coelomate versus acoelomate body plan (2) Protostome versus deuterostome development (3) Radial versus bilateral symmetry b. Describe the differences between the terms in each of the following pairs. 3 points)In the context of an experiment, description of: What induction is: Cells influence neighboring cells What induction does: Changes gene expression Induces differentiation Alters subsequent development Inducing Tissue (organizer) Induced Tissue and what it forms Examples: Dorsal lip of blastopore - induces gastrulation or neurulation of "belly" ectoderm Optic vesicle - induces lens formation in epidermal ectoderm Notochord - induces neurulation of neural ectodermĭEVELOPMENT QUESTION 1990 (EVOLUTION): L. 2 points) AccomplishesEstablishes germ layers or triploblastic embryo ecto-, meso-, endo- (or ento-)derm (must mention 2)Forms gastrulaEstablishes embryonic axesForms gastrocoel (archenteron, gut or digestive system)Internalizes yolkObliterates blastocoelMoves cells to sites where poised for organogenesis (max. 3 points)Formation of yolk plugFormation of blastoporeInvagination ("folds in", "pushes in")InvolutionEpiboly/cell migrationProliferation/movement forward of notochordal tissue (chordamesoderm, primary mesoderm) internally from blastopore.Forward movement of mesodermal wings (lateral plate mesoderm, somitic mesoderm) internally from blastopore. 2 points) AccomplishesForms neural tube (CNS, nerve cord, spinal cord, brain, nervous system)Forms neurulaForms neural crests (max. 3 points)Epidermal thickening, flattening in dorsal midline (neural plate formation)Plate develops longitudinal depression (neural groove, neural folds)Neural folds fuseNeural tube pinches free of epidermis, sinks inward Notochord (chordamesoderm) required for neurulation (max. 2 points) AccomplishesForms blastula or hollow ball of cellsForms blastocoelForms blastomeres (micromeres, macromeres)Forms or increases DNA in embryoProduces unequal distribution of cytoplasmic contents in blastomeres (max. 3 points)Mitotic or cell division, or increase in cell numberNo cellular growthHoloblastic (complete division)UnequalRadial (Indeterminant)Involves use of maternal RNA 1st vertical 2nd vertical, perpendicular to 1st3rd horizontal, perpendicular to 1st and 2nd, unequalGrey crescent establishes planes of cleavage Divisions more rapid at animal pole (max. PETERSON/ECHSĝiscuss the processes of cleavage, gastrulation, and neurulation in the frog embryo tell what each process accomplishes.ĝescribe an experiment that illustrates the importance of induction in development. STANDARDS: 1 point for each major item under each major headingCLEAVAGE (max. You may download this entire file in Microsoft Word Format, or you may preview the questions and standards by year through your web browser by selecting the appropriate year.ĭEVELOPMENT QUESTION 1988: L. The masking of the original mode of mesoderm formation.AP Biology Development Questions andStandards The division of blastopore caused the division of mesoderm. The inducing cause of such division is the elongation of the body, while the endoblast is still in an embryonic condition.Ģ. Phoronis is the first step towards a complete division of the blastopore. The nephridia, which might have remained either wholly or in part with the anterior, have attached themselves entirely to the posterior mesoderm.Įxtension of this interpretation to the other Tripleblastiea-ġ. The necessity of an early attainment of a terminal position by the anus caused the ectoderm to grow more rapidly than, the emdoblast, and resulted in a division of the mesoderm into anterior and posterior parts.Ĥ. The rapid growth of ectoderm in the median ventral line nearly succeeded in destroying the continuity of the primitive streak.ģ. A gastraea with slit-like mouth and a pair of lateral diverticula giving rise to mesoderm was the ancestor of Phoronis.Ģ. Preliminary interpretation suggested by these facts of the development of Phoronis-ġ. The nephridial openings to the exterior are parts of the blastopore. The mesoderm arises in an anterior pair of endoblastic modified diverticula, and in a posterior pair of ectoblastic diverticula connected by a few mesodermic cells derived from the middle of a primitive streak.ģ. The blastopore gives rise to both mouth and anus.Ģ. ![]()
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