Levels of Organization

NGSS Unit 6

7th Grade Science

What do all of these pictures have in common?

Multicellular Organisms

• In unicellular (single-celled) organisms, the single cell performs all life functions. However … multi-cellular organisms have various levels of organization.

• Individual cells may perform specific functions and also work together for the good of the entire organism.

• Multicellular organisms have 5 Levels of Organization from simple to complex.

Level 1: Cells

• Basic structural unit of living things

• May serve a function within the organism

• Examples: • blood cells, nerve cells, bone

cells ,etc.

Level 2: Tissues

• Made up of cells of similar structure and function and work together to perform a specific function.

• Examples:• Blood, nervous, bone, etc.

Level 3: Organs

• Made up of tissues that work together to perform a specific activity.

• Examples:• Heart, brain, skin, etc.

Level 4: Organ Systems

• Groups of two or more organs that work together to perform a specific activity.

• Examples: • Circulatory system, digestive

system, nervous system, endocrine system, etc.

Level 5: Organisms

• Entire living things that can carry out all living processes.

• Usually made up of organ systems, but an organism can be made up of only one cell such as a bacteria.

• Examples:• Bacteria, mushroom, sunflower,

human, etc.

Levels of Organization Cells are the simplest level of organization.

However … what makes up cells?

Exit Slip – Writing Prompt

Complete on the next empty page in your Science Notebook.

• In your own words, define what a cell is. Also explain how one single cell can create a multi-cellular organism such as a human being. In your explanation, use levels of organization to support your response.