48 Atoms in Living Molecules How Algae and Plants Obtain Food How Animals Obtain Food Securing Energy from Food Carrying Food and Oxygen 49 49 50 CHAPTER 5 TYPES OF LIVING THINGS 52 54 Bacteria Archaea 55 Protists 58 59 60 Fungi Symbiosis Plants Animals 61 62 64 66 66 66 CHAPTER 6 THE EVOLUTION OF LIVING THINGS Seven Functions of Living Things Movement Sensitivity Respiration Nutrition Growth Reproduction 67 69 70 71 Excretion 73 74 75 CHAPTER 7 TAXONOMY AND GENETICs Carolus Linnaeus Evolutionary Theory Mechanism of Heredity Gregor Mendel Modern Developments 78 81 81 83 85 86 CONCLUSION GLOSSARY FOR MORE INFORMATION FOR FURTHER READING INDEX 88 91 92
INTRODUCTION A male robin feeds an earthworm to his unfledged young Scientists who study birds are known as ornithologists Mike Truchon Shutterstock com
INTRODUCTION ife has existed on Earth for billions of years always changing and adapt ing New forms of life have evolved as old ones have become extinct From the first simplest organisms Earth has given rise to mil lions of species Some are familiar the various kinds of plants and animals that we know but many more are so tiny or so rare that they are known only to a handful of specialists Scientists who study living organisms are biologists Within that broad definition are dozens of subspecialties Some biologists study a certain category of life while oth ers focus on the patterns that connect all life forms Biologists look at the big picture environments and organisms as well as the tiny building blocks of cells and molecules Although there has been life on Earth for a long time it was not always here In its first billion years Earth was a planet made up only of inanimate substances such as minerals and gases The mysteries surrounding how life first came to exist are some of the most fascinating in the field of biology Equally fascinating are the questions concerning how life forms have adapted or failed to adapt to their envi ronments Why are some plants carnivorous Why did the dodo bird become extinct Why are some bacteria deadly to humans but cause
