Organism: The

An organism is any individual living system, such as an animal, plant, fungus, or bacterium. To be considered "alive," an organism generally must:

No organism exists in a vacuum. They are part of an : The Organism

Physical features like a turtle's shell or a cactus's spines. An organism is any individual living system, such

Heterotrophs (must eat other organisms for energy). 4. Survival Mechanisms such as an animal

React to external changes in its environment. 2. The Hierarchy of Structure Organisms are organized in a "ladder" of complexity.

Organisms rely on others for food, oxygen, and decomposition.

Scientists categorize every organism into three primary domains: