Unit 4: Classification of Living Things

Characteristics of Living Things All living things: 1. Have Cellular Organization 2. Share Chemicals of Life 3. Need Energy 4. Respond to Surroundings 5. Grow and Develop 6. Reproduce

Cellular Organization Cell- The basic unit of structure and function in an organism Unicellular- single celled Multicellular- many cells

Chemicals of Life Carbohydrates- also called sugars, used for energy Proteins- building material of cells Lipids- building material of cells Nucleic Acids- genetic material, gives cell instructions and controls cell’s activities

Energy Use Cells need energy to function and repair themselves! The sun is the ultimate source of energy for all life on earth.

Response to Surroundings Stimulus- a change that causes an organism to react (ex: temp, light, sound) Response- an action or change in behavior…happens because of stimulus

Growth, Development, Reproduction Growth- getting larger Development- becoming more complex Reproduction- passing on genetic material

Life Comes From Life Spontaneous Generation- living things can arise from nonliving things- HAS BEEN DISPROVEN It took hundreds of years and lots of experiments to prove this

Life Comes From Life Francesco Redi designed one of the first controlled experiments. In his experiment, Redi showed that flies do not spontaneously arise from decaying meat.

Life Comes From Life Louis Pasteur’s carefully controlled experiment demonstrated that bacteria arise only from existing bacteria.

The Needs of Living Things 1. Water- can only live a few days without water. Need it to obtain chemicals, digest, grow, move, and reproduce 2. Food- Used for energy source a. Autotrophs- Make their own energy using sunlight (plants) b. Heterotrophs- Obtain food by eating other organisms

3. Living Space- organisms compete for space and resources 4. Stable Internal Conditions a. Homeostasis- maintaining stable internal conditions so cells can properly function (our body temp) The Needs of Living Things

Scientists classify so we can make sense of the world and living things, makes living things easier to study. Classification- the process of grouping things based on their similarities Taxonomy- the scientific study of how living things are classified Classification

Binomial Nomenclature- Created by Linneaeus, 2-part naming system. Uses Genus and Species. Ex: Homo sapiens Genus- contains similar, closely-related organisms. Pumas and house cats are in Genus Felis. They have sharp, retractable claws, and hunt. Species- group of similar organisms that can mate with each other and produce viable offspring Classification

Levels of Classification- The more levels that 2 organisms share, the more characteristics they have in common Kingdom Phylum Class Order Family Genus Species Classification

As you move down the levels of classification, the number of organisms decreases. The organisms at lower levels share more characteristics with each other. Levels of Classification

Prokaryotes- Don’t have a nucleus Eukaryotes- have a nucleus Autotrophs- Make food from sun Heterotrophs- obtain food from eating autotrophs and other heterotrophs Terms

Cell Wall- rigid layer of material that surrounds some cells to provide protection & support (plants, fungi, bacteria) animal plant bacteria No cell wall

Three Domains of Life In the three-domain system of classifications, all known organisms belong to one of three domains–Bacteria, Archaea, or Eukarya.

Three Domains of Life Bacteria (Prokaryotes, Autotrophs & Heterotrophs, Cell Walls) Kingdom: Eubacteria On your body, in foods we eat. Most aren’t harmful. Archaea (Prokaryotes, Autotrophs & Heterotrophs, Cell Walls) Kingdom: Archaebacteria Live in extreme environments (dark, hot, salty, etc). Archaea means “ancient” in Greek. Eukarya (Eukaryotes) Kingdoms: Protists- Can’t be classified as anything else. Very Diverse. (NO Cell Walls) Auto/heterotrophs, uni/multicellular. Seaweed, Paramecium Fungi- Mushrooms, molds, mildew. Most are multicellular. Heterotrophs. (Cell Walls) Absorb nutrients from decaying organisms. Plants- trees, moss, peas. Multicellular. (Cell Walls) Most live on land. Autotrophs. Very diverse. Animals- Multicellular. Heterotrophs. (NO Cell Walls) Very diverse.

Keys are used to determine the identification of organisms. Statements are in pairs Taxonomic (Dichotomous) Key