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Defining Life

There are 7 Characteristics of life, all living things MUST have all of these characteristics in order to be defines as a living thing.


Definitions vary between many different sources. This is just one definition.


Click on the boxes below to learn more about each topic.

Image Credit: Chris Packard - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=59184218

#1 Growth and Development

All organisms (living things) must grow. Sometime its a single-celled organism whose 1 cell grows, then divides. Multi-cellular organisms make more cells in order to grow and get bigger.


See Growth in cells for more details

#2 Reproduce Offspring

Reproduce means to make more. Organisms can simply make a copy of itself using asexual reproduction. Some organisms mate with another using sexual reproduction to reproduce.


See Reproduction in cells for more details

#3 Heredity of Traits

Passing of traits from parents to their offspring (kids).

#4 Homeostasis Stable Inner Conditions

Organisms what to remain the same. Homeostasis is an organisms resistance to change in order to keep the same inside and not change. Haman's keeping a temperature of 98.6OF is an example of homeostasis.


See Khan Academy Homeostasis for more details.

#5 Metabolism Energy from Chemical Reactions

Being able to take chemical energy (food) and turn it into energy that the organism can use to do the other functions of a living thing, like growing.


See Cellular Respiration for more details

#6 Cellular Structure and Composition

All living things are made of cells, the basic unit of life. Some living things are made of only one cell such as bacteria and protists and some fugi. Other organism have more then 1 cell such as plants and animals.


See Cells for more details

#7 Respond to the Environment

All organism respond to their environment. A response is an action caused by a change in the environment. The change in the environment is called a stimulus. When you jump or scream when you are scared is an example of a response to your environment.


Learn More

Khan Academy What is Life?

Next to The Microscope