Chapter 32 - CR

Chapter 32 - CR - Chapter 32 An Introduction to Animal...

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Page 1 of 19 Chapter 32 Chapter 32 An Introduction to Animal Diversity
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Page 2 of 19 32.1: Animal are multicellular, heterotrophic 32.1: Animal are multicellular, heterotrophic eukaryotes with tissues that develop from eukaryotes with tissues that develop from embryonic layers embryonic layers Characteristics that define animals as a group: Animals are heterotrophs that ingest their food Most use enzymes to digest food only AFTER ingestion Animals are multicellular eukaryotes Animals lack the structural support of cell walls Their bodies are held together by structural proteins such as collagen and intracellular junctions They have specialized nervous and muscle tissue Most animals reproduce sexually with the diploid stage usually dominating the life cycle
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Page 3 of 19 After a sperm fertilizes an egg: The zygote undergoes cleavage , leading to the formation of a blastula The blastula undergoes gastrulation , resulting in the formation of embryonic tissue layers and a gastrula Zygote Cleavage Eight-cell stage Cleavage Blastula Cross section of blastula Blastocoel Blastocoel Gastrula Gastrulation Endoderm Ectoderm Blastopore Figure 32.2
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Page 4 of 19 The life cycles of many animals include a larval stage A sexually immature form of an animal that is morphologically distinct from the adult stage Eventually undergo a metamorphosis All animals, and only animals, have Hox genes that regulate the development of body form The Hox family of genes has been highly conserved Duplications of this gene family produced a wide diversity of animal morphology
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Page 5 of 19 32.2: The history of animals may 32.2: The history of animals may span more than a billion years span more than a billion years The animal kingdom includes not only great diversity of living species, but the even greater diversity of extinct species The common ancestor of living animals may have lived 1.2 billion–800 million years ago It may have resembled modern choanoflagellates , protists that are the closest living relatives of animals Single cell Stalk Figure 32.3
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This note was uploaded on 04/07/2008 for the course BIO 103 taught by Professor Mannino during the Fall '08 term at Long Island U..

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Chapter 32 - CR - Chapter 32 An Introduction to Animal...

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