Biology is generally categorized in different levels starting with the smallest and widening out to include everything on Earth.

  1. Energy and metabolism
  2. Molecules and heredity
  3. Adaptation and evolution
  4. Patterns of organization

Atom- smallest unit of matter that maintains the properties of an element
Molecule- group of atoms held together by covalent bonds; make up cells
Cells- living thing that has a membrane to keep it apart from others; makes up tissues
Tissues- material which organs are made of
Organs- a group of assorted tissues which makes up the organ system and performs bodily functions
Organ System- the processes which allow an organism and its related parts to function properly
Organism- one individual, one body of the population
Population- all organisms of one particular species in a community
Community- all living organisms in a certain ecosystem that interact
Ecosystem- all biotic and abiotic factors in a certain area
Biosphere- all the ecosystems on earth