Classification and Dichotomous Keys

Bell work 9/17 Continue on your bellwork sheet from last week! Think about the different ways humans classify things. List five groups of things that humans classify, such as library books, department store merchandise, and addresses. Is there such a thing as too much classification? What happens when you put something in the wrong group? Can objects or ideas belong in more than one group at the same time? Record your responses on your bell work sheet.

Classification Classification: the division of organisms into groups, or classes, based on specific characteristics. Scientists classify organisms to help make sense and order of the many kinds of living things in the world. Before the 1600’s scientists divided organisms into two groups: Plants and Animals.

Taxonomy Taxonomy: the science of describing, naming, and classifying organisms. Taxonomists use an 8-level system to classify living things based on shared characteristics. Did King Phillip Come Over For Grape Soda?

Branching Diagram Shows relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characters.

Levels of Classification Every living thing is classified into 1 of 3 domains: Bacteria, Archaea, and Eukarya Then sorted into kingdoms, phylum, class, order, family , genus, and then species.

Scientific Names Before Linnaeus simplified the naming of living things, they could have had a name that was 12 words long. Two-Part name: Felis domesticus (common house cat) 1st part of the name Felisis the genus name. The 2nd part domesticus is the specific name. Naming rules help scientists communicate clearly about living things.

Rules of Names All Genus names begin with a capital letter “Felis” All specific names begin with a lowercase letter “domesticus” Usually both words are underlined or italized. Scientific names are usually in Latin or Greek and contain info about the organism.

Dichotomous Key An aid that is used to identify organisms and that consists of the answers to a series of questions. Using a D.K.: there are only two alternative responses for each statement. From each pair of statements, choose the statement that describes the organism or is directed to another statement, until the organism is identified.

Dichotomous Key

The Domain Archaea (traditional Kingdom Archaebacteria) Archaea is one of the three major divisions (domains). Once thought to be bacteria. Single-celled organisms One of two kinds of prokaryotes which means they do not have a nucleus. Most live in extreme environments like the hot springs of Yellowstone because of their tough outer cell wall and protective enzymes. Archaea have been around at least 3 billion years and scientists believe they are very closely related to some of Earth’s earliest life forms.

The Domain Bacteria Bacteria prokaryotic (no nucleus). Bacteria are single-celled. Bacteria can be found everywhere…in soil, water, and even on and inside the human body. For example, E coli is present in the human intestines where it produces vitamin K. Another kind of bacteria converts milk into yogurt. Some bacteria cause diseases (pneumonia) while others make chemicals that help fight disease.

The Domain Eukarya The Kingdom Protista Members of the kingdom Protista commonly called protists, are single-celled or simple multicelluar organisms. They are eukaryotic (have a nucleus). Protista contains many kinds of organisms, including protozoans, algae (plant-like), slime/molds (animal-like), and euglenoids.

The Domain Eukarya, continued The Kingdom Fungi They are multicellular. Fungi do not perform photosynthesis or eat food. Instead, fungi break down surrounding stuff with digestive juices and absorb the nutrients. Molds and mushrooms are examples of the complex, multicelluar members of the kingdom Fungi.

The Domain Eukarya, continued The Kingdom Plantae Consists of complex multicellular organisms. They are eukaryotic (have a nucleus). They have cell walls. They make food through photosynthesis.

The Kingdom Animalia

The Domain Eukarya (continued) The kingdom Animalia contains complex, multicellular organisms that don’t have cell walls. Most able to move around and have specialized sense organs. However, an exception is the sponge, a simple animal that cannot move. Examples include ants, beetles, lizards, fish, birds, apes, elephants, and more.