Notes 2.1

1. Notes 2.1 Scientists develop systems for classifying living things.

2. Scientists classify millions of species. • Until the 1600s, scientists classified organisms according to their appearance. • The invention of the microscope allowed scientists to see structures and organisms that were not visible before.

3. Classification and Taxonomy • Classification: the process of arranging organisms into groups based on similarities • Taxonomy: the science of naming and classifying organisms • The purpose of classification and taxonomy is to make information easier to find and understand.

4. Classification and Taxonomy • Until 1700s scientists could not agree on a system • Both overly long Latin scientific names and common names can be confusing.

5. Using Classification • Scientists use similarities and differences among species, including appearance, biology, and genetics. • The more characteristics 2 organisms share, the more similar their scientific names should be in the classification system. • See examples on page 45B.

6. Taxonomists study biological relationships. • Taxonomists: the scientists who classify and name organisms based on their similarities and differences. • Taxon: a group of organisms that share certain traits • Taxonscan be broad (animal) or more specific (cat). • A single species found in a fossil record can be the ancestor of many species on Earth today.

7. Taxonomists study biological relationships (continued) • In order to classify organisms, scientists compare a variety of traits. • Trait: a characteristic or behavior • If 2 organisms share a trait, taxonomists try to determine if they share that trait because they share an ancestor.

8. Continued • Page 47B—the seahorse shares more traits with a leafy sea dragon than the sargassum seaweed or sargassum fish. • Taxonomists take evidence and try to reconstruct the evolution of a species. • Then they place the species in the classification system.

9. Physical Evidence • Primary devices used—eyes and measuring devices • Collect samples and note characteristics—size, color, weight, how obtain energy, internal structures, outward appearance • Individuals of a species have many similarites and some differences.

10. Physical Evidence • Skeletons, shells, and other hard parts of organisms fossilize more easily. • Scientists observe and measure this evidence. • They also compare bones. • All this physical evidence helps scientists see that all living organisms are related by evolution. • Those most closely related share a more recent ancestor.

11. Genetic Evidence • Scientists can compare the components of a gene from one organism with the components of the same gene from another organism. • Genetic evidence usually supports physical evidence. • See p. 49B—Red pandas are more closely related to raccoons than Giant Pandas

12. Review Questions 49B • 1. Classification allows taxonomists to organize a great deal of data so that it is easier to find and understand.

13. Number 2 • Taxonomists study biological relationships to discover how one species evolved as compared with another species.

14. Number 3 • Scientists look at DNA and compare genes of organisms.

15. Number 4 • Having a universal naming system allows people speaking different languages to refer to all organisms the same way. It’s easier to understand.

16. Number 5 A marbled godwit would have marbled feathers, wings, feet, and a beak.

17. Number 6 • Compare physical traits, such as color, size, weight and how they get energy. Analyze bones; compare to fossils; compare DNA.

18. Quiz Fill-in Terms Classification Evolution physical System taxons Taxonomy Traits genetic

19. Extended Response • Explain how scientists may use physical and genetic evidence to determine how closely related two species of birds are. • Quiz Wednesday!