Go to Section: Order From Chaos When you need a new pair of shoes, what do you do? You probably walk confidently into a shoe store, past the tens or hundreds of pairs of shoes you don’t want and straight to the kind you do want. How do you find them? Shoes are organized in the store in categories. People organize objects by grouping similar objects together. Section 18-1 Interest Grabber

Go to Section: 1.Consider the task facing early biologists who attempted to organize living things. How might they have begun? 2.Suppose that you have been given a green plant, stringy brown seaweed, a rabbit, a mushroom, a worm, and a grasshopper. You’ve been asked to organize these things into categories that make sense. How would you do it? 3.Decide on your categories and write each on a sheet of paper. Next to each category, write the defining characteristics of that category. Then, write in the organisms that fall into each category. Section 18-1 Interest Grabber continued

Go to Section: 18–1Finding Order in Diversity A.Why Classify? B.Assigning Scientific Names 1.Early Efforts at Naming Organisms 2.Binomial Nomenclature C.Linnaeus’s System of Classification Section 18-1 Section Outline

Go to Section: Section 18-1 Flowchart Linnaeus’s System of Classification Kingdom Phylum Class Order Family Genus Species

Go to Section: Grizzly bearBlack bearGiant panda Red fox Abert squirrel Coral snake Sea star KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Carnivora FAMILY Ursidae GENUS Ursus SPECIES Ursus arctos Section 18-1 Figure 18-5 Classification of Ursus arctos

Go to Section: One Big Family? How can you determine if one organism is closely related to another? It may seem easy, but it isn’t, and looks are often deceiving. For example, roses and orchids are both flowering plants, but roses grow on bushes or vines and have thorns. Many orchids don’t even grow in soil—they can grow in trees! Rose and orchid blossoms look very different, and roses and orchids cannot produce hybrids, or offspring of crosses between parents with different traits. Section 18-2 Interest Grabber

Go to Section: 1.Do you think roses and orchids are closely related? Explain your answer. 2.Now, apply the same logic to dogs. Different breeds of dogs—such as a Labrador retriever and a collie—can breed and produce offspring. So what is the difference between the rose-orchid combination and the Lab-collie combination? 3.What defines a species? Is appearance important? What other factors might be considered? Section 18-2 Interest Grabber continued

Go to Section: 18–2 Modern Evolutionary Classification A.Which Similarities Are Most Important? B.Evolutionary Classification C.Classification Using Cladograms D.Similarities in DNA and RNA E.Molecular Clocks Section 18-2 Section Outline

Go to Section: CLADOGRAM AppendagesConical Shells Crab Barnacle Limpet Crab Barnacle Limpet CrustaceansGastropod Molted exoskeleton Segmentation Tiny free-swimming larva Section 18-2 Traditional Classification Versus Cladogram CLASSIFICATION BASED ON VISIBLE SIMILARITIES

Go to Section: CLASSIFICATION BASED ON VISIBLE SIMILARITIES CLADOGRAM AppendagesConical Shells Crab Barnacle Limpet Crab Barnacle Limpet CrustaceansGastropod Molted exoskeleton Segmentation Tiny free-swimming larva Section 18-2 Traditional Classification Versus Cladogram

Go to Section: My Way or the Highway Categories that are used to organize an assortment of things should be valid. That is, they should be based on real information. However, categories should be useful, too. Suppose that you are taking a survey of traffic. You sit at the side of a busy intersection and record the vehicles you see in one hour. Section 18-3 Interest Grabber

Go to Section: 1. What categories could you use to organize your count of vehicles? 2.Look at your list of categories. Are all of them equally useful? 3.Is there more than one valid and useful way to organize living things? Section 18-3 Interest Grabber continued

Go to Section: 18–3Kingdoms and Domains A.The Tree of Life Evolves B.The Three-Domain System C.Domain Bacteria D.Domain Archaea E.Domain Eukarya 1.Protista 2.Fungi 3.Plantae 4.Animalia Section 18-3 Section Outline

Go to Section: Section 18-3 Concept Map are characterized by such as and differing which place them in which coincides with which place them in which is subdivided into Living Things Kingdom Eubacteria Kingdom Archaebacteria Eukaryotic cells Prokaryotic cells Important characteristics Cell wall structures Domain Eukarya Domain Bacteria Domain Archaea Kingdom Plantae Kingdom Protista Kingdom Fungi Kingdom Animalia

Go to Section: DOMAIN KINGDOM CELL TYPE CELL STRUCTURES NUMBER OF CELLS MODE OF NUTRITION EXAMPLES Bacteria Eubacteria Prokaryote Cell walls with peptidoglycan Unicellular Autotroph or heterotroph Streptococcus, Escherichia coli Archaea Archaebacteria Prokaryote Cell walls without peptidoglycan Unicellular Autotroph or heterotroph Methanogens, halophiles Protista Eukaryote Cell walls of cellulose in some; some have chloroplasts Most unicellular; some colonial; some multicellular Autotroph or heterotroph Amoeba, Paramecium, slime molds, giant kelp Fungi Eukaryote Cell walls of chitin Most multicellular; some unicellular Heterotroph Mushrooms, yeasts Plantae Eukaryote Cell walls of cellulose; chloroplasts Multicellular Autotroph Mosses, ferns, flowering plants Animalia Eukaryote No cell walls or chloroplasts Multicellular Heterotroph Sponges, worms, insects, fishes, mammals Eukarya Classification of Living Things Section 18-3 Figure Key Characteristics of Kingdoms and Domains

Go to Section: Kingdoms Eubacteria Archaebacteria Protista Plantae Fungi Animalia DOMAIN EUKARYA DOMAIN ARCHAEA DOMAIN BACTERIA Section 18-3 Figure Cladogram of Six Kingdoms and Three Domains

Video Contents Videos Click a hyperlink to choose a video. Panthera leo?, Part 1 Panthera leo?, Part 2

Video 1 Click the image to play the video segment. Video 1 Panthera leo?, Part 1

Video 2 Click the image to play the video segment. Video 2 Panthera leo?, Part 2

Internet Links from the authors on the search for new species Interactive test For links on classification, go to and enter the Web Code as follows: cbn For links on domains of life, go to and enter the Web Code as follows: cbn Go Online

Section 1 Answers Interest Grabber Answers 1.Consider the task facing early biologists who attempted to organize living things. How might they have begun? Students may say that early biologists attempted to formulate logical systems for organizing the diversity of life. 2.Suppose that you have been given a green plant, stringy brown seaweed, a rabbit, a mushroom, a worm, and a grasshopper. You’ve been asked to organize these things into categories that make sense. How would you do it? Students may group the plantlike, sessile organisms (the plant, seaweed, and mushroom) together, grouping the others as animals. 3.Decide on your categories and write each on a sheet of paper. Next to each category, write the defining characteristics of that category. Then, write in the organisms that fall into each category. Remind students that organizational systems are human-made, and there are no right or wrong ones. Some, however, are more useful than others.

Section 2 Answers Interest Grabber Answers 1.Do you think roses and orchids are closely related? Explain your answer. Students may say that their different growth habits and inability to hybridize indicate that they are not closely related. 2.Now, apply the same logic to dogs. Different breeds of dogs—such as a Labrador retriever and a collie—can breed and produce offspring. So what is the difference between the rose-orchid combination and the Lab-collie combination? Students may know that all domestic dogs are a single species. 3.What defines a species? Is appearance important? What other factors might be considered? Students may suggest that a species is defined by its members’ ability to interbreed, regardless of appearance.

Section 3 Answers Interest Grabber Answers 1. What categories could you use to organize your count of vehicles? Students’ answers may include, type of vehicle, color, age, or manufacturer. 2.Look at your list of categories. Are all of them equally useful? Students may suggest that the usefulness of the criteria depends on the intent of the study. 3.Is there more than one valid and useful way to organize living things? Students should conclude that the same set of living things could be categorized in several ways, depending upon the criteria used.

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