Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Living Things
Name: Carmen
Status: student
Grade: K-3
Location: WA
Country: N/A
Date: 5/4/2005

What is a living organism?

My guess the ability to undergo life processes, growth. It takes in some thing that converts to material to sustain. With that, I looked up the definition.

1. An individual form of life, such as a plant, animal, bacterium, protist, or fungus; a body made up of organs, organelles, or other parts that work together to carry on the various processes of life. Reading the definition, I'll drop my growth comment. See, I was interested in ,"What's a rock?" The small rock can't just be pieces if bigger rocks. I might be wrong, but I felt a rock can accumulate layers, the atmosphere, or surroundings, tack on. So, it could seem that rocks grow, but that won't be sustain processes hence while appearing to grow, wouldn't be an organism.

J. Przewoznik

This is an excellent may seem simple but after being a biologist for 30 years I am still not sure. Philosophers (thinkers of great thoughts) have had a hard time with this question too. The problem is that whatever you might say about something "living" you can probably imagine a "machine" someday being able to do... if they can't already. There is a book by a scientist called "I Robot" that Hollywood made into a movie (kind of...not as good as the book) that imagines different robots that each have a certain thing we think only we humans can the ability to love, or cry or lie...its an interesting book. What makes a living thing different from non-living and what makes a human a human...keep on thinking about it! If you figure it out e-mail me. I want to know.


This is one of my favorite questions. In fact, scientists don't entirely agree on the answer. It is generally agreed that all living things have a few features in common: they all respond to their environments, they all grow and develop, they all use energy, they all can reproduce, they all maintain a steady chemical balance inside themselves (homeostasis), they are all composed of cells, and all populations of organisms evolve over time.

There are a few examples of things that are difficult to classify as living or non-living. Viruses, for example, have some features of living things (reproduction, evolution, energy use) but they lack other features (cells, homeostasis). Some people who study viruses do consider them to be alive, but most do not.

Or take the example of a chicken egg that has just been laid. Let's say there are no roosters around. Clearly, the egg will not develop into a chick, and we should probably consider it to be non-living. But it is, essentially, a cell from a living chicken and it clearly began as a living cell and it still has all the biochemistry of a living cell. So at what point did it "cross the line" from a living cell to a non-living one? It's very difficult to come up with a completely satisfactory answer.


Hi Carmen-

You probably already know what living organisms are like. All the world's animal, plants, and germs are living organisms.

They move around, eat some kind of food, grow bigger, make new ones of their own kind, and they do smart things to survive when the world around them changes a little. Smarter than a rock, anyway.

In a year or two your school will probably teach you the "rules" for being a living organism. Most of them are listed in the paragraph above.

The world has a few in-between things which we can't decide for sure whether to call them "living" or not. Virus-germs multiply, but they never grow bigger. they are either built to their full (very tiny) size, or they aren't working viruses yet. And they can't do it without "taking over" the guts of a bigger, fancier organism. Most scientists think of them as the smallest possible living organism. Crystals (like sugar crystals) grow bigger, but they don't do anything smart. If you break one into pieces you have many new crystals to grow bigger. But we don't think of crystals as being alive at all. We think of them as rocks, which nature is accidentally building more of.

Personally, I think smart, complicated, goal-oriented behavior is the real definition of life. Living things "try" to do something. Usually they try to survive.

Hope that explains it for you...

Jim Swenson

A living organism is made up of cells. That is the only thing required in order for you to be able to call it alive. Cells are to small to see. Every part of our body is made of cells. Plants are made of cells. The difference is some cells look different from other cells and they have different "jobs" to do to keep the organism alive.

Grace Field

Click here to return to the General Topics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory