Unit 6 Lesson 6 Classification of Living Things Copyright © Houghton Mifflin Harcourt Publishing Company 1

Unit 6 Lesson 6 Classification of Living Things Florida Benchmark SC.6.N.2.2 Explain that scientific knowledge is durable because it is open to change as new evidence or interpretations are encountered. SC.6.N.3.4 Identify the role of models in the context of the sixth grade science benchmarks. SC.6.L.15.1 Analyze and describe how and why organisms are classified according to shared characteristics with emphasis on the Linnaean system combined with the concept of Domains. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Sorting Things Out! Why do we classify living things? Unit 6 Lesson 6 Classification of Living Things Sorting Things Out! Why do we classify living things? Scientists classify living things based on characteristics that living things share. Classification helps scientists to answer questions about organisms. Classification helps a scientist keep living things organized. Copyright © Houghton Mifflin Harcourt Publishing Company 3

How do scientists know living things are related? Unit 6 Lesson 6 Classification of Living Things How do scientists know living things are related? Physical characteristics can indicate that two organisms are similar or related. Scientists also study how organisms develop from an egg to an adult to determine if organisms are related. Copyright © Houghton Mifflin Harcourt Publishing Company 4

How do scientists know living things are related? Unit 6 Lesson 6 Classification of Living Things How do scientists know living things are related? Chemical characteristics can indicate whether organisms are similar or related. Scientists use genetic material to look for mutations and genetic similarities. Proteins and hormones also can show if organisms are related. Copyright © Houghton Mifflin Harcourt Publishing Company 5

What’s in a Name? How are living things named? Unit 6 Lesson 6 Classification of Living Things What’s in a Name? How are living things named? Carolus Linnaeus simplified classification with a two-part scientific name. A species is a group of organisms that are very closely related. Members of the same species can mate and produce fertile offspring. Copyright © Houghton Mifflin Harcourt Publishing Company 6

How are living things named? Unit 6 Lesson 6 Classification of Living Things How are living things named? A genus includes similar species. The genus is the first part of a scientific name. The genus name is always capitalized. The species name follows and is lowercase. All organisms have a unique two-part scientific name that is italicized or underlined. Copyright © Houghton Mifflin Harcourt Publishing Company 7

What are the levels of classification? Unit 6 Lesson 6 Classification of Living Things What are the levels of classification? Taxonomy is the science of describing, classifying, and naming living things. Scientists use an eight-level classification system. Each level is more specific than the one before it and contains a smaller group of living things. Copyright © Houghton Mifflin Harcourt Publishing Company 8

What are the levels of classification? Unit 6 Lesson 6 Classification of Living Things What are the levels of classification? Domain Kingdom Phylum Class Order Family Genus Species Copyright © Houghton Mifflin Harcourt Publishing Company 9

What are the levels of classification? Unit 6 Lesson 6 Classification of Living Things What are the levels of classification? Copyright © Houghton Mifflin Harcourt Publishing Company 10

Triple Play What are the three domains? Unit 6 Lesson 6 Classification of Living Things Triple Play What are the three domains? Scientists used to use a six-kingdom classification system, but later added the domain. A domain represents the largest differences among organisms in classification. The three domains are Bacteria, Archaea, and Eukarya. Copyright © Houghton Mifflin Harcourt Publishing Company 11

What are the three domains? Unit 6 Lesson 6 Classification of Living Things What are the three domains? Domain Bacteria is made up of prokaryotes that typically have a cell wall and reproduce by cell division. Domain Archaea is made up of prokaryotes that differ from bacteria in their genetics and in the makeup of their cell walls. Copyright © Houghton Mifflin Harcourt Publishing Company 12

What are the three domains? Unit 6 Lesson 6 Classification of Living Things What are the three domains? Domain Eukarya is made up of all eukaryotes. Eukaryotes have cells with a nucleus and membrane-bound organelles. Plants, animals, protists, and fungi in the Domain Eukarya can be single-celled or multicellular. Copyright © Houghton Mifflin Harcourt Publishing Company 13

My Kingdom for a Eukaryote! Unit 6 Lesson 6 Classification of Living Things My Kingdom for a Eukaryote! What kingdoms are in Eukarya? Kingdom Animalia contains multicellular organisms that lack cell walls, are typically able to move around, and have specialized sense organs. Kingdom Plantae consists of multicellular organisms that have cell walls, cannot move around, and make their own food. Copyright © Houghton Mifflin Harcourt Publishing Company 14

What kingdoms are in Eukarya? Unit 6 Lesson 6 Classification of Living Things What kingdoms are in Eukarya? Kingdom Protista are single-celled or simple multicellular organisms such as algae, protozoans, and slime molds. Kingdom Fungi are single-celled or multicellular organisms that get energy by absorbing materials and have cells with cell walls but no chloroplasts. Copyright © Houghton Mifflin Harcourt Publishing Company 15

How do classification systems change? Unit 6 Lesson 6 Classification of Living Things How do classification systems change? Millions of organisms are not named. New organisms do not always fit into the existing classification system. Scientists are constantly changing their thoughts on classification based on new information. Copyright © Houghton Mifflin Harcourt Publishing Company 16

How are classification relationships illustrated? Unit 6 Lesson 6 Classification of Living Things How are classification relationships illustrated? Branching diagrams are often used in classification. A cladogram is a branching diagram that shows relationships among species. Organisms to the right have a particular characteristic. Organisms on branches to the left do not. Copyright © Houghton Mifflin Harcourt Publishing Company 17

How are classification relationships illustrated? Unit 6 Lesson 6 Classification of Living Things How are classification relationships illustrated? Organisms to the right have a particular characteristic. Organisms on branches to the left do not. Copyright © Houghton Mifflin Harcourt Publishing Company 18

Keys to Success How can organisms be identified? Unit 6 Lesson 6 Classification of Living Things Keys to Success How can organisms be identified? A dichotomous key uses a series of paired statements to identify organisms. The pairs of statements are numbered. Once you choose a correct statement from a pair, you are directed to a new pair of statements until the organism is identified. Copyright © Houghton Mifflin Harcourt Publishing Company 19