beginning of material for Exam 03 VERTEBRATES Questions to think about 1 What are the four uniting features of chordates including the location and function of each characteristic reference Fig following lecture point 2 Notochord Precursor to backbone A rod like structure providing support and running the length of the animal Located between the gut and nerve cord Postanal tail An extension of the body that runs past the anal opening In some species like humans this feature is only present during the embryonic stage Pharyngeal slits Connect the pharynx muscular tube that links the mouth cavity and the esophagus to the outside Openings from the mouth to the external environment Used in oxygen uptake fish Only occur in embryonic phases in most groups including humans Nerve Cord A hallow tube of nerve tissue located dorsal to the notochord Develops into brain and spinal cord Nervous system a what phase of the life cycle are most of these features found Embryonic 2 What can we infer about phylogeny from ontogeny Give two examples of this Also explain how the presence of bilateral symmetry in echinoderms relates to this concept Ontogeny Embryonic development selection pressures are relaxed in embryonic development We can see an evolutionary history by making inferences about this development Embryonic development is the slowest changing trends Example assumption is that since the embryos look similar that they came from similar ancestors Echinoderms show bilateral symmetry as larvae but loose it as they transition to adults This shows us that a trait that the common ancestor of echinoderms had bilateral symmetry and perhaps this will come to be something that we don t see in the larvae of echinoderms but in embryonic development 2 What is an invertebrate chordate what chordate features does such an animal possess Fig 23 35 A Chordate without a backbone They possess all Chordate features but some may be lost in the adults a what can we conclude about the same genes being expressed in a lancelet and a vertebrate brain Fig at point 1b in lecture slide 13 Lancelet is a primitive vertebrate It is good evidence that they are homologous common origin These genes are transcription factors 4 What does the vertebral column replace and what does it enclose in adults Backbone encloses the nerve chord The vertebral column replaces the notochord Nerve cord gives rise to the nervous system Noto cord precursor of the backbone 5 Explain the selective pressure involved in the evolution of jaws An animal with jaws can more easily Crush food and more easily Catch food The selection pressure is more efficient food processing which directly effects survival 1 Lobed fin Rod shaped fin bones surrounded by thick muscular layer 6 What is the significance of the lobed fin and why would it evolve It allowed fish to walk underwater It led to the development of legs tetrapods a what important evolutionary feature happened in the lobe fin line think They developed into legs 7 Interpret figure that follows the photo of the lobe fin fish on tetrapod evolution including fossil evidence Tetrapod evolution Evolution of legs The figure displays pretty good fossil evidence that tetrapod evolution arose from lobed fin legless organisms 8 In which animals does the amniotic egg occur and give the function of each extraembryonic membrane in this egg Fig 23 47a Reptiles and mammals Amniotic egg A shelled egg surrounding four extraembryonic membranes and embryo nourishing yolk This evolutionary adaptation permitted mammals and reptiles to live and reproduce in drier environments than most amphibians Yolk sac Encloses nutrients Chorion Gas Exchange Allantois Gas Exchange and encloses waste Amnion Protects embryo Amniotic cavity Embryo A young animal or young plant sporophyte that is still contained within a protective structure such as a seed egg or uterus Shell a give at least two functions of the shell in amniotes Allows gas exchange and prevents the thing from drying out 9 Regarding the series of figures under point 6 of lecture depicting the transition from a 2 chambered heart of a fish to a 4 chambered heart of a bird mammal Pulmonary circulation the portion of the cardiovascular system which carries deoxygenated blood away from the heart to the lungs and returns oxygenated oxygen rich blood back to the heart Systemic circulation the part of the cardiovascular system which carries oxygenated blood away from the heart to the body and returns deoxygenated blood back to the heart a what does the lungfish circulation have that represents an advance over a fish Lungfish have a partially divided atrium one side receiving oxygenated blood from b what does the amphibian circulation system have that represents an advance The pulmonary and systemic circuits are partially separated and they have a 3 c what does the reptile heart have that represents an advance over the amphibian The ventricle is partly divided by a septum which directs oxygenated blood to the d what does the crocodile bird mammal heart have that represents an advance the lung and the other side receiving deoxygenated blood from the body over the lungfish chambered heart heart body and oxygen depleted blood to the lungs over the reptile 2 They have 4 chambered hearts their pulmonary and systemic circuits are totally separate 10 How many chambers does the heart of a fish have a lungfish an amphibian a reptile a crocodile a bird A 2 Chambers B 2 Chambers C 3 Chambers D 3 Chambers E 4 Chambers F 4 Chambers 11 What is the advantage of a separation of oxygenated blood from deoxygenated blood The blood is separated by the septum By keeping them unmixed it keeps the oxygen levels higher in blood being distributed to the body Mixing of blood lowers the oxygen content lower oxygen content lowers the effective function of tissues 12 For ectothermy and endothermy define each word list at least one group of animals for each and give an advantage and a disadvantage of each recalling our discussion in class with Christian about his reticulated python Ectotherm An animal that is dependent on external heat sources for regulating its body temperature A Reptiles B The advantage takes place in cases where there is shortage of food Ectothermic animals can survive for very long time without food Endotherm An animal that can control its body temperature by the expenditure of its own metabolic energy B They can stay mobile during cold seasons because they make their own No because it is