Characteristics of Life What defines LIFE?

1. Cells All living things have at least one cell.

2. Organization Living things are highly organized, from the smallest part to the largest. Complex organism, like humans, are multicellular. Cells are organized into tissues, which have a common function like a muscle. Tissues are organized into organs like the heart.

3. Energy Use All living organisms are able to get their own energy from food or produce their own energy.

4. Respond to the environment All living organisms are able to react /respond to a stimulus in their environment. Homeostasis – maintain stable internal conditions.

5. Growth All living things are able to develop and grow. They may do this by growing larger cells or by cell division to add more cells.

6. Reproduction All living organisms are able to create other organisms similar to themselves. Reproduction is not essential for the survival of an individual organism, it is essential for the continuity of life.

7. Adaptation All living creatures are able to change behaviors and over time physical traits to better fit their environment.

Many non-living things have some characteristics of life. For example: ice crystals may grow, a television uses energy, and water moves. All seven characteristics of life must be present for something to be alive.

Levels of Organization

1. Cellular Level The smallest unit of life capable of carrying out all the functions of living things.

2. Tissue Level A group of similar cells that perform a specific in an organism

3. Organ Level Several different types of tissues that function together for a specific purpose

4. Organ System Level Several organs working together to perform a specific function

5. Organism Level All the organ systems of the body functioning together with one another Makes up the organism

6. Population Level A group of organisms of the same species that live together in a particular location Species -

7. Community Level All the populations of different species living in a particular location

8. Ecosystem Level All the communities of an area plus the nonliving factors of the environment

9. Biosphere All the ecosystems