Levels of

Organization in Living

ThingsHow living things are organized

Vocab Refresher

FunctionWhat

something is

used for

Something’s

job

Purpose, role

StructureThe way

something is

constructed or

made

The way the

parts of

something are

arranged

ALL organisms perform

the functions of lifeReproduce

Grow and develop

Obtain and use ENERGY

Response to their environment (stimuli) to maintain balance (homeostasis)

Adapt to their environment over time (as a species, not individual)

Unicellular Organisms

Some organisms are made of only one cell

The cell performs ALL of the functions necessary for life

Uni- = one or single

Examples: Bacteria, protists, yeast

Multicellular Organisms

Have various levels of organization within them

Individual cells may perform specific functions (different types of cells)

Cells work together for the good of the entire organism

Cells depend on one another

Levels of organization

Cells

Tissues

Organs

Organ systems

Organism

CELLSBasic unit of structure

and function in living things (CELL THEORY!)

Serve specific functions (different types for different jobs!)

Examples: blood cells (erythrocytes), nerve cells (neurons), bone cells (osteocytes)

TISSUES Made up of cells that

are similar in structure and function

The cells work together to perform a specific activity

Examples: blood, nervous, bone

4 basic types in humans:

connective (blood, fat, ligaments, cartilage, bones, tendons),

epithelial (skin),

muscle (smooth, skeletal, cardiac)

nerve

ORGANS

Made up of tissues that

work together to perform a

specific activity

Examples: heart, brain, skin

ORGAN SYSTEMS

Groups of organs working together to perform specific functions for the organism

Examples: circulatory, muscular, digestive

ORGANISMS

Entire living things carrying out all life’s functions

Multicellular organisms made up of organ systems

Examples: mushroom, sunflower, human, fish

Unicellular – only made up of a cell (Ex. Bacteria, protist)

Levels of Organization

Cells

Tissues

Organs

Organ Systems

Organisms

Basic

Unit

of

Life