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Biology Chapter 32 Objectives

Biology Chapter 32 Objectives - Chapter 32 An Introduction...

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Chapter 32: An Introduction To Animal Diversity What Is An Animal? 1. Animals are defined by their inability to construct their own organic food and thus, in most cases, ingest them. Animals are also defined by their lack of support of the cell walls and they are instead held together by structural proteins like collagen. Animals also reproduce sexually and the diploid stage usually dominates the life cycle. Animals also have three unique types of intercellular junctions: tight junctions, desmosomes and gap junctions. 2. Hox genes control the expression of other genes and thus producing different morphological features of animals. The Origins of Animal Diversity 3. The first generally accepted fossils of animals are 575 million years old and are collectively called Ediacaran fauna for the Ediacara Hills of Australia. These indicate that animals emerged from 542 million to 1 billion years ago. 4. The Cambrian explosion is significant because it is a period of time in which animal diversity accelerates dramatically. Some suggest that new predator-prey
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