Biology  5/e   Raven/Johnson
	Student   Online Learning Center

Chitin: Chitin is modified from cellulose in which a nitrogen group has been added to the glucose units. Chitin is tough, resistant surface material.

The origin of species: Genetically based adaptation to the environment is the basis for selection for survival. Increased survival of better adapted members of a population is the source of new species.

Classification: Three domains are recognized: Archebacteria, Eubacteria, and Eukarya. There are six recognized kingdoms: Archebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia. Kingdoms are divided into phyla (sometimes called divisions in plants), which are subdivided into classes. Classes are divided into orders, and in turn, families, genera, and species.

Copyright ©1998 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use and Privacy Policy.
McGraw-Hill Higher Education is one of the many fine businesses of The McGraw-Hill Companies.
For further information about this site contact mhhe_webmaster@mcgraw-hill.com.