1. Revisiting Characteristics of Life FOSS: Diversity of Life
Alive vs. Organism
Revisiting Characteristics of Life
FOSS: Diversity of Life

2. What is an Organism?
Any living thing - a plant, an animal, or any other life-form - that is free-living (i.e. not a part of a larger living organism.

3. Questions to Ponder… Can a single living cell be a living organism?
Can a single living cell not be a living organism?
Is a paramecium cell a living organism?
Is an Elodea leaf cell a living organism?

4. Answers… Can a single living cell be a living organism?
Yes.
Can a single living cell not be a living organism?
Yes
Is a paramecium cell a living organism?
Is an Elodea leaf cell a living organism?
No.

5. Paramecium vs. Elodea Paramecia
Paramecia itself is a single, individual, cell.
Is an organism.
Is made of just one cell.
Single-celled organisms.
Elodea
Individual green “bricks” in Elodea are individual cells.
Is an organism.
Made of many cells.
Multicellular organism.
Individual Elodea cell is alive, but not an organism.

6. How are Elodea cells and Paramecium cells different?

7. “Alive” and “Organism”
Characteristics of life (needs water, responds to the environment, needs food, eliminates waste, gas exchange, reproduces) are the functions and requirements that are common to all things we consider living.

8. “Alive” and “Organism”
Characteristics of Cells:
Cells are alive.
Life happens in cells and only in cells.
Cells are fundamental units of life.
Some cells (i.e. paramecium), live alone.
Some cells (i.e. Elodea leaf cells), live with millions of cells.
Both of these cells are alive, and both do all the things we recognize as living.

9. Not All Cells Are Organisms
Not all cells are able to live independently.
Paramecia are single-celled organisms in a kingdom of life called Protista.
Single-celled organisms, life paramecia, are members of a kingdom of life that includes organisms that are similar to some of the very first life-forms on Earth.

10. Protists Are Not Animals
Animals are multicellular.
Protista is a separate kingdom whose members are mostly single-celled.

11. Is there anything else that we should add to the list that is true of all living things?