The diversity of cellular life

7.4 BiologyMr. Hines

Unicellular organisms

Sometimes the cell is the organism.For example, all protists and bacteria are

single celled organisms1 cell = 1 organismSingle celled organisms are called unicellular.Unicellular organisms dominate life on earth

(Most common and diverse)

Amoeba

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Euglena

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Paramecium

Colony of cells

When unicellular organisms clump together, it is called a colony.

Cells within a colony are individual organisms living with others.

There is no cell specialization.

Volvox

Multicellular organisms

Organims that are made of many cells are called multicellular.

A multicellular organism will have specialized cells which perform specific tasks for the survival of the organism.

For example, liver cells, brain cells, nerve cells, muscle cells, blood cells etc.

Levels of organization

Cells form tissues (layers of cells)Tissues form organsOrgans form organ systems.

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Hydra

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Newt

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Dog

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Aye Aye

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Just Kidding

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What is the difference between a colony of cells and a multicellular

organism?A colony is made of individual organisms

living together and there is no cell specialization.

A multicellular organism is made of specialized cells living together that are needed for the survival of the organism