AP Study Guide Ch 18

AP Study Guide Ch 18 - Chapter 18 Study Guide The Evolution...

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Chapter 18 Study Guide The Evolution of animal Diversity The duck-billed platypus lays eggs and has a bill and webbed feet like a duck. It has fur and a tail like a beaver; it has mammary glands like any other mammal. It is a monotreme or an egg-laying mammal. Australia is full of special mammals called monotremes and marsupials. The niches that were being filled with placental mammals on other continents were left empty when Australia broke away from Pangaea. Without competition from other placental mammals, monotremes and marsupials filled in the empty niches and became the dominant mammals in Australia. Animal Evolution and Diversity Animals are eukaryotic, multicellular heterotrophs that lack cell walls and obtain nutrition by ingestion. This distinguishes animals from fungi that digest their food first and then absorb it. Animals have unique types of cell junctions. Most animals have muscle cells for movement and nerve cells for sensory perception. Animals are, with the exception of the gametes, composed of diploid cells. The life cycle of most animals includes a dominant, diploid adult that produces eggs or sperm by meiosis. These gametes fuse to form a zygote. The zygote develops into the adult animal, passing through a series of embryonic stages Colonial protists of a few identical, flagellated cells. Larger, hollow, spherical colonies that ingested organic materials suspended in the water around the colony. Colonies with cells specialized for somatic.) and reproductive functions. Differentiated entities with an infolded, temporary digestive region. “Protoanimals,” completely infolded, with two-layered body walls The modern animal phyla evolved during the Cambrian period, 542 mya, a 15 million–year period of explosive evolution. o 1. Ecological causes: increased dependency on the predator/prey relationship. o 2. Geological changes: atmospheric oxygen may have reached a critical threshold that was high enough to support the active lifestyle of animals. o 3. Genetic causes: the development of the Hox genes supported the diversity associated with variations in the spatial and temporal arrangement of the genes during embryonic stages of development. A hydrostatic skeleton is a fluid-filled cavity that acts like a skeleton for soft-bodied animals.
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This note was uploaded on 04/05/2012 for the course BIOL 101 taught by Professor Lexicon during the Spring '11 term at Ohlone.

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AP Study Guide Ch 18 - Chapter 18 Study Guide The Evolution...

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