Bio 1306 Test 2 review

Bio 1306 Test 2 review - Chapter 31 1 The most recent...

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Chapter 31 1. The most recent ancestor to animal clade - Colonial Flagellated Protist 2. Evolutionary trade-offs - Characteristics of an animal in one life stage may improve ability for one activity, but reduce performance in some other activity Examples – frog & penguin; mostly animals who have a high mortality rate or more developed 3. Dipoblastic animals – Triploblastic animals – have 3 cell layers: ectoderm, endoderm, & mesoderm (humans) 4. Symmetrical – divided into similar halves on at least one plane Asymmetrical – no symmetry: sponges Radial – one main axis around which body parts are arranged: cnidarians & ctenophores Bilateral – single plane through the anterior-posterior midline divides into “mirror- image halves” Occurs in animals that move in one direction Vertebrates A plane at right angles to the midline divides animals into ventral (belly) & dorsal (back) surfaces Associated with cephalization: concentration of sensory organs & nerve tissue at the anterior end 5. 2 patterns of development after formation of blastopore: a. Protostomes (“mouth first”) – the blastopore develops into the mouth
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b. Deuterostomes (“mouth second”) – the blastopore develops into the anus; mouth develops later (humans) 6. Segmentation – bodies are divided into segments Facilitates specialization of body regions Evolved independently several times Radiation of arthropods was based on changes in a segmented body plan 7. Body Cavity – 3 types based on the presence of an internal, fluid-filled body cavity Acoelomate – lack a fluid filled body cavity Pseodocoelomate – body cavity is a pseudocoel, a fluid-filled space in which organs are suspended (muscles are only on the outside) Coelomate – a coelom lined with a layer of muscle tissue (peritoneum – which also
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Bio 1306 Test 2 review - Chapter 31 1 The most recent...

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