Section 1.1 The Study of Life

Earth is home to an incredible diversity of life Biodiversity  The variety of life in an area. Increases as you move from the poles to the equator. More living things are able to survive in warmer climates.

Levels of Organization Levels go from big to small Biosphere  Every part of Earth that supports life. Ecosystem  A collection of organisms and the nonliving things in an area. Community  A collection of all the different populations that live in an area. Population  Members of the same species that are living in the same area at the same time. Species  a group of organisms that have the ability to interbreed and produce viable offspring.

Organism  An individual living thing. Organ System  Two or more organs that work in a coordinated way to carry out similar functions. Organ  Group of different types of tissues that work together to perform a specific function or related functions. Tissue  A group of cells that work together to perform a similar function. Cell  The basic structure of life. Organelle  A specialized structure that performs a specific function within a cell.

Molecule  Two or more atoms held together by covalent bonds. Atom  The smallest basic unit of matter.

Unifying themes of biology Section 1.2 Unifying themes of biology

All living things share certain characteristics Made of Cells: Some are unicellular, but most are multi-cellular.

Respond to a Stimulus: Stimulus  anything (internal of external) that causes a response Response  an internal or external reaction