1. Uni Multi
All organisms are made up of one or more cells.
•One cell •Many cells
•Unicellular organism
must perform all of
the necessary
functions to stay alive.
•Require fewer
resources and can live
in harsher conditions
than multicellular
organisms.
•Specialization. Each type of
cell has a specific job. It
makes the organism more
efficient.
•Longer life than a unicellular
organism
•Usually larger than
unicellular organisms.
Multicellular organisms grow
by making more cells, not
by making making their cells
larger.
cellular cellular

2. Cell
Tissue
Organ
Organ system
Organism
Organization in Multicellular Organisms
The cell is the basic unit of all living things.
All organisms are made up of one or more cells.
The cell is the basic unit of all living things.
Begin as single cell  become many cells  differentiate
and specialize.
All tissues are made up of cells.
Tissue is a group of cells that perform a specific function.
All organs are made up of tissues.
An organ is made up of two or more tissues working
together to perform a specific function.
All organ systems are made up of organs.
An organ system is made up of two or
more organs working together to perform a
specific function.
Organisms are made up of organ systems.
All organisms are made up of one or more cells.

3. Level 1 : Cells
• Cells can be specialized
(have a certain function)
• Function = job
• Function is related to the cell
structure

4. Level 2: Tissues
• Tissue = group of cells that work
together to do a specific job
• Ex: Heart muscle tissue
is made of heart
muscle
cells
• Animals have 4 types of
tissue: nerve,
muscle,
connective, protective
• Plants have 3 types of
Image from kleenex.com
Image from www.cytochemistry.net

5. Level 3: Organs
• Organ = structure that is made
up of 2 or more tissues
working together to get a
specific job done
• Ex: Stomach – muscle tissue
moves food, special tissues
make chemicals to digest
food, connective tissue holds
stomach together, nervous
tissue sends messages back
and forth between the
stomach and brain
Image from nlm.nih.gov

6. Level 4: Organ Systems
• Organ system = group of
organs working together
to perform a specific
function
• Each organ system has
a specific job
• Ex: Digestive system is
made of several organs
including the stomach
and intestines
Image from nih.gov

7. Organism
Organ
Organ system
Cell
Tissue
Organization in Multicellular Organisms