Levels of Organization-- Answer key
Review of Cells
● Cells are the smallest unit of life
● There is smaller than a cell that is living
● Cells are specialized for certain jobs
○ Each one has a specific job to perform
● Cells DO NOT work alone -- they depend on each other to function.
Tissues
● Tissues are groups of cells working together to perform a specific job
● There are several different types of tissues:
● Muscle -- soft tissue making up muscles
● Connective -- connects, supports organs
● Epithelial -- skin
● Nerve-- main part of the nervous system
● Each type of tissue performs a specific job.
Organs
●
Organs are :
Groups of tissues working together to perform a certain job
● Different organs in our bodies have different jobs to do:
○ Examples: HEART: pumps & circulates blood throughout the body
LUNGS: organs responsible for exchanging gases
STOMACH: breaks down food
BRAIN: control organ for entire body
● If one organ quits working and doing its job, other organs may quit working also.
Organ Systems
● Organ systems are the highest level of organization within an organism
● An organ systems are: groups of organs working together to perform a
specific job
● Examples include: cardiovascular system, nervous system, digestive system
● If an organ system begins to fail, other organ systems may stop working and
the organism may die.
Organism
● This is the highest level of organization.
● Any living thing is called an organism, no matter if it’s one-celled or many-celled.
● An organism is a collection of cells, tissues, organs, and organ systems.
● What are some examples of organisms? Humans, cats, dogs, fish, bacteria,
trees, plants
