Classifying Living Things Similarities and Differences Among Organisms

Classification Classification is the process of grouping things based on their shared traits. Biologists use classification to organize living things into groups, so that the organisms are easier to study. The scientific study of how living things are classified is called taxonomy.

Living vs. Nonliving Things Object Cells Grow And Develop Use Energy Reproduce Respond To Stimuli Adapt Change Nonliving No Maybe Living Yes

Living Things Scientists have identified and described about 1.5 million species of organisms and are not sure how many more species remain to be discovered. Living things vary in shape, size, and other characteristics…however all living things share certain similarities.

Structure All living things are composed of cells. A cell is the basic unit of structure and function in an organism. Unicellular (single celled) Multicellular (many cells)…specialized cells (blood cell, skin cell, brain cell, etc…)

Growth and Development All living things grow and develop. Some organisms show very limited growth, like bacteria, and others change completely through metamorphosis. Some organisms hatch from eggs and other organisms are born alive.

Reproduction All living things reproduce. Reproduction involves passing on hereditary information to their offspring.

Response to Stimuli All living things respond to stimuli. A stimulus is anything that causes a response. Living things respond to various stimuli, including: light, sound, touch, smell, and taste. Some living things have specialized structures to detect stimuli and to respond to it. Some organisms respond slowly (plants w/sunlight) and others respond quickly (hot stove).

Energy Use All living things use energy to carry out functions such as growth, development, reproduction, and responding to stimuli. In addition…living things use energy to perform functions such as digestion, respiration, excretion, and circulation. Not all organisms depend on the same energy source. Plants = light energy Animals = take in nutrients from plants, other animals, or both

Adapt to Change All species change themselves and adapt to change around them over time. Organisms develop adaptations, or traits/behaviors, that increase an organisms chance of survival. Not all adaptations follow the same pattern. Bacteria that are resistant to antibiotics have changed over the last 50 years, whereas the alligator has not changed in the last 200 million years.

Classification System Carolus Linnaeus is the Swedish scientist who developed a classification system based on the organisms’ observable features; it’s morphology. Linnaeus’s naming system is called binomial nomenclature because each organism is given a two part name.

Binomial Nomenclature The first part of the organism’s name is its genus. This is a classification grouping that contains similar, closely related organisms. The second part of the organism’s name is its species. A species is a group of similar organisms that can mate and produce fertile offspring. These terms are unique and no other species can have this same name. Scientific names are designed to tell you something about an animal's relationships with other animals. Humans = Homo sapiens

7 Levels of Classification Today’s classification system uses several levels to classify organisms. The more characteristics that organisms have in common, the more levels they share. Kingdom Phylum Class Order Family Genus Species

5/6 Kingdoms of Organisms Bacteria (Monera) Archaebacteria Eubacteria Protists Fungi Plants Animals

Recent Events Recently scientists have proposed that living things be classified into even larger groups called domains. The three domains would be: Bacteria, Archaea, and Eukarya.