CONTENTS 



PAGE 



INTRODUCTION • You and Biology 3 



UNIT ONE . What Is Life? 9 



1 • What Distinguishes Living Things? 11 



2 • How Can We Know the Different Kinds of Living Things? 29 



3 • How Does Man Differ from Other Living Things? 45 



4 • How Do Individuals Differ? 61 



UNIT TWO • Under What Conditions Can We Live? 79 



5 • What Have Water and Air to Do with Being Alive? 80 



6 • What Is the Relation of Food to Life? 96 



7 • What Kinds of Stuff Serve as Human Food? 114 



8 • How Do Food Stuffs Come into Being? 137 



UNIT THREE • How Do Living Things Keep Alive? 161 



9 • How Do Living Things Get and Manage Their Food? 163 



10 • How Does Food Reach the Different Parts of the Body? 185 



11 • How Do Plants and Animals Breathe? 201 



12 • How Do Living Things Get Rid of Wastes? 214 



13 • How Do Organisms Resist Injury? 228 



UNIT FOUR • How Do the Parts of an Organism Work Together? 249 



14 How Do Living Things Adjust Themselves? 251 



15 • What Do the Nerves Do? 273 



16 • How Do Glands Work? 301 



17 • What Makes the Organism a Unity? 322 



UNIT FIVE • How Do Living Things Originate? 341 



18 • Growth and Development 343 



19 • Reproduction of Life 367 



20 • Reproduction in Flowering Plants 398 



21 • Infancy and Parenthood 417 



VII 



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