Welcome to the Student Web site for Life, The Science of Biology, Sixth Edition, by William K. Purves, David Sadava, Gordon H. Orians, and H. Craig Heller. This Web site is designed to help students review key concepts from the textbook through interactive exercises and learning tools. Resources are organized by chapter of the textbook and by content type. To access resources, please select a Chapter or Category below.

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Chapter 1: An Evolutionary Framework for Biology   PART ONE The Cell   Chapter 2: Small Molecules: Structure and Behavior Chapter 3: Macromolecules: Their Chemistry and Biology Chapter 4: The Organization of Cells Chapter 5: Cellular Membranes Chapter 6: Energy, Enzymes, and Metabolism Chapter 7: Cellular Pathways That Harvest Chemical Energy Chapter 8: Photosynthesis: Energy from the Sun   PART TWO Information and Heredity   Chapter 9: Chromosomes, the Cell Cycle, and Cell Division Chapter 10: Genetics: Mendel and Beyond Chapter 11: DNA and Its Role in Heredity Chapter 12: From DNA to Protein: Genotype to Phenotype Chapter 13: The Genetics of Viruses and Prokaryotes Chapter 14: The Eukaryotic Genome and Its Expression Chapter 15: Cell Signaling and Communication Chapter 16: Development: Differential Gene Expression Chapter 17: Recombinant DNA and Biotechnology Chapter 18: Molecular Biology and Medicine Chapter 19: Natural Defenses against Disease   PART THREE Evolutionary processes   Chapter 20: The History of Life on Earth Chapter 21: The Mechanisms of Evolution Chapter 22: Species and Their Formation Chapter 23: Reconstructing and Using Phylogenies Chapter 24: Molecular and Genomic Evolution Chapter 25: The Origin of Life on Earth   PART FOUR The Evolution of Diversity   Chapter 26: Bacteria and Archaea: The Prokaryotic Domains Chapter 27: Protists and the Dawn of Eukarya Chapter 28: Plants Without Seeds: From Sea to Land Chapter 29: The Evolution of Seed Plants Chapter 30: Fungi: Recyclers, Killers, and Plant Partners Chapter 31: Animal Origins and Lophotrochozoans Chapter 32: Ecdysozoans: The Molting Animals Chapter 33: Deuterostomate Animals: Large Brains and Complex Behavior   PART FIVE The Biology of Flowering Plants   Chapter 34: The Plant Body Chapter 35: Transport in Plants Chapter 36: Plant Nutrition Chapter 37: Plant Growth Regulation Chapter 38: Reproduction in Flowering Plants Chapter 39: Plant Responses to Environmental Challenges   PART SIX The Biology of Animals   Chapter 40: Physiology, Homeostasis, and Temperature Regulation Chapter 41: Animal Hormones Chapter 42: Animal Reproduction Chapter 43: Animal Development Chapter 44: Neurons and Nervous Systems Chapter 45: Sensory Systems Chapter 46: The Mammalian Nervous System: Structure and Higher Functions Chapter 47: Effectors: Making Animals Move Chapter 48: Gas Exchange in Animals Chapter 49: Circulatory Systems Chapter 50: Animal Nutrition Chapter 51: Salt and Water Balance and Nitrogen Excretion Chapter 52: Animal Behavior   PART SEVEN Ecology and Biogeography   Chapter 53: Behavioral Ecology Chapter 54: Population Ecology Chapter 55: Community Ecology Chapter 56: Ecosystems Chapter 57: Biogeography Chapter 58: Conservation Biology

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