Name:
Date:
28.1 Levels of Organization
KEY CONCEPT : The human body has five levels of organization.
Specialized cells develop from a single _____________
(fertilized egg).
 A zygote is the cell resulting from the union of
an egg and sperm.
• Organisms are made up of specialized cells.
Rve
Red Blood Cells
•
•
•
Zygotes first divide into embryonic ________ __________.
Stem cells can become any of 200 types of cells in the human body.
Stem cells develop in two stages.
•
_________________, or committing to become one cell type
•
__________________, or acquiring specialized structures and functions
Specialized cells function together in
tissues, organs, organ systems, and the
whole organism.
• Specialized cells perform specific
tasks.
• Tissues are groups of similar cells
working together.
• The four types of tissues in the human
body are:
1.
2.
3.
4.
Nerve Cell
Five Levels of Organization


Level One:
Definition: ________ are the basic unit of structure and
function in living things.


Level Two:
Definition: __________ are a group of similar cells that
work together to perform a specific function.


Level Three:
Definition: __________ are different tissues working
together.


Level Four:
Definition: ________ ____________ are two or more
organs working together.


Level Five:
Definition: _______________ is all organ systems working together.
There are 11 major organ systems in the human body