Biology Chapter 34 Objectives

Biology Chapter 34 Objectives - Chapter 34 Objectives 1....

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Chapter 34 Objectives 1. The 3 different phyla of chordates include 2 phyla of invertebrates and 1 phylum of vertebrates. The invertebrates are echinoderms, sea stars and sea urchins, then there are urochordates and the cephalochordates which are more closely related to vertebrates than to other invertebrates. The vertebrates are their own group. 2. They have a notochord a longitudinal flexible rod located between the digestive tube and the nerve chord, dorsal hollow nerve chord which develops from a plate of ectoderm that rolls into a tube located dorsal to the notochord, a pharyngal slits or clefts in most chordates the pharyngeal clefts develop into slits which open into the outside of the body, these slits allow water entering the mouth to exit the body without passing through the entire digestive tract, and a muscular post anal tail which contains skeletal elements and muscles and propels the animal. 3. The first subphylum is tunicates which belong to the deepest lineage of chordates includes hagfish, the second subphylum is lancelets which are bladelike and include branchiostomes, and the final subphylum is craniates which have a head such as humans. 4. The evidence for includes many documented instances in evolutionary transitions called phaedomorphosis. The evidence against is that the degenerate adult stage appears to be a derived trait that developed after the branching from other chordates. 5. The vertebrate brain is an elaboration of an ancestral structure similar to the lancelet’s simple nerve chord tip. 6. The importance of genetic duplication is that craniates posses 2 sets of Hox genes as opposed to the lancelets and the tunicates which only possess one. 7. Neural crest cells disperse throughout the body from the embryo and give rise to many of the unique structures of craniates including teeth, parts of the skull, the inner layer of the skin of the facial region, several types of neurons, and the sensory capsules from which eyes and other sensory organs develop. 8.
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This note was uploaded on 08/29/2009 for the course BIOL 101 taught by Professor Sakji during the Fall '08 term at Linn Tech.

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Biology Chapter 34 Objectives - Chapter 34 Objectives 1....

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