Biology  5/e   Raven/Johnson
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Evolutionary theory: Variations occur within populations. The higher the degree of polyploidy, the greater potential for variation. Some variations will give members of a population greater capacity to adapt and to be selected by nature for survival and reproduction. The accumulated variations and the selection for survival and reproduction of those organisms with the most advantageous variations is the essence of the evolutionary process.

Classification: Six kingdoms are recognized: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia. Kingdoms are divided into classes. Classes are divided into orders and, in turn, families, genera, and species.

Protosomes and deuterostomes: Protostomes form their mouth from the blastopore, and the anus develops elsewhere. Protostome embryos cleave by spiral cleavage. Deuterostomes form their anus from the blastopore, and the mouth develops elsewhere. Deuterostomes have radial cleavage of the embryo.

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