Atom
smallest "functional" unit of all chemical
substances (molecules). Cannot be broken down.
Molecule
Two or more atoms connected by chemical
bonds.
Organelle
Membrane-bound sub-cellular structure
with it's own unique function.
Cell
The simplest unit of an organism.
Tissue
The association of many cells of the same
type
Organ
Two or more types of tissue combined to
perform a common function
Organism
A living thing that that maintains an
internal order and is separate from the environment
Species
Group of related organisms sharing a distinct
form
Population
Group of individuals of the same species
that occupy the same environment.
Community
Assemblage of populations of different
species living in the same place/time
Ecosystem
Biotic community of populations and the
abiotic environment affecting that community
Biosphere
All regions on the Earth, and in the
atmosphere, where organisms exist
Six common characteristics:
Composed of cells
� Metabolism
� Respond to stimuli
� Growth and development
� Reproduction
� Ability to evolve
Unicellular
� Single celled organisms
� (algae, protists, etc)
Multicellular
Many celled organisms
� (plants, humans, etc)
Metabolism:
All the chemical reactions that occur
within an organism which allow it to
take in and use energy
Respond to environment:
Organisms must be able to respond to changes in the
environment to survive.
Examples:
� The ability of a mammal to
respond to cold temperatures
by growing additional fur.
Growth & Development
Growth: Production of more
or larger cells.
Development: Changes in
the state of a cell, tissue, organ
or organism
Reproduction
The process by which organisms
produce new organisms (offspring)
Biological Evolution
The change in genetic material
(DNA) of a population of
organisms from one generation to
the next.