Levels of Organization Learning Targets Describe the levels of organization of life or how life is organized. Organization of Life Atom Molecule Cell Organelle Cell Tissue Organ system Organism Population Community Ecosystem Biosphere Atom The smallest particle of an element that retains the properties of that element. Building block of all matter. An element is a pure substance that cannot be separated into simpler substances by chemical or physical means. Molecule The smallest possible particle of a compound. A compound is two or more elements chemically combined. Organelles Specialized structures within eukaryotic cells that perform important cellular functions. Similar to organs in an animal. Cells The basic unit of all organisms; all living things are composed of cells. Tissues A group of cells that work together to perform a specific function. Examples: muscle, epithelial, connective and nervous. Connective Tissue Organ A group of two or more tissues organized to perform a specific life function. Examples: heart, lungs, liver, kidney. Organ System Multiple organs that work together to perform a specific life function. Examples: circulatory, respiratory, digestive. Organism A single individual of a specific species. Ex: an individual diamond back rattlesnake or an individual white bass. Population A group of individuals of the same species that live together in the same area at the same time. Example: All the white bass in Lake Pleasant. Communities Consists of all of the populations of different species (or all of the living things) that live and interact in an area. All the white bass, striped bass, bluegill, crawdads, shad, birds, plants, plankton, etc. that live in Lake Pleasant. Ecosystems Are made up of a community of organisms and their abiotic (non- living) environment. Includes the dead wood, rocks, water, oxygen, dirt, etc. in Lake Pleasant. Check Point What is missing in a community that is included in an ecosystem? Identify each as an organism, population, community or ecosystem. All of the deer, elk, grass and squirrels on the Kaibab Plateau. One elk on the Kaibab Plateau. All of the deer, elk, grass, squirrels, soil, air, and rocks on the Kaibab Plateau. All the mule deer on the Kaibab Plateau. The Biosphere The part of Earth where life exists. It extends from the ocean floor to several kilometers into the air. .