Abiotic (from the Greek a- and bios, "life") describes the components of an ecosystem which are not, and have never been, alive. While we commonly list only the LAW (light, air, water, and substrate/soil) as abiotic factors, such physical phenomena as temperature, pH level and air or water pressure are also considered abiotic. All of these have profound effects on the biotic and cultural elements of an ecosystem.
All life requires abiotic factors. At the base of the food web, producers require water, carbon dioxide from air and sunlight to produce food, as well as using minerals from soil. Consumers also require air (whether in the form we breathe or as dissolved oxygen in water) and water, and most need light to see. At the end of the cycle, decomposers break down biotic material into its abiotic components, releasing the water, gasses, and minerals needed to begin the cycle again.
By adapting to cope with widely differing levels of abiotic factors, a wide vareity of organisms have flourished across the planet in deserts and oceans, dense forests and open prairies, the cold of the tundra and the heat of the tropics. Some species, such as humans, are able to thrive in many different abiotic environments, while others are very sensitive to changes in the abiotic makeup of their ecosystem.
Other terms often confused in discussions of "living" are "dead," "non-living" or "never-living," "biotic" and "abiotic."
"DEAD" (or "Was Alive") implies that the object was once living.
"NON-LIVING" (or "Never Living") suggests that the object has never had the ability to carry out the life functions outlined above e.g. metals, water, air, soil.
"BIOTIC" means "pertaining to life" and refers to anything that is alive, was alive, or is part of something that was alive. A leaf can be said to be BIOTIC, as it is part of a living organism, but the same leaf would not normally be classified as LIVING as it is just part of a living system.
Below are common ideas children in grades K-6 have about this topic, compiled from research on children's ideas about science (see the Session 1 Children's Ideas Bibliography). Consider what evidence might refute this idea, and why a child would be likely to believe this?
1. If it moves, it is alive.
Many things that move aren’t alive, such as cars, clouds, and flowing water. The living things that are most familiar to children are likely to be animals that move. Since they consider animals to be alive, they may associate the characteristic of movement with life.
2.If it seems to move by itself, it’s alive; if it’s moved by something else, it’s not alive.
A shadow moves by itself, but it’s not alive. Fire also moves by itself. Once children recognize that there are non-living things that can be moved by an external force — like clouds moved by the wind, or a bicycle pedaled by a person, they may make the finer distinction that something is alive only if it can move itself.
3. If it makes light or a noise, it’s alive.
A burning candle and a flashlight make light but are not alive. A ringing bell and a piano make noise, but are not alive. Younger children may believe this because they associate “doing something” with being alive.
4. It’s not alive unless it’s “doing something.”
A potato doesn’t appear to be doing anything, yet a potato is alive. If you plant a potato in a suitable environment, it will grow into a potato plant. At the cell level, all living things are constantly “doing something,” even if this can’t be detected. Children may hold this idea because they connect life with activity, particularly movement. In contrast, familiar examples of nonliving things — like rocks or books — don’t demonstrate activity.
5. To be alive, something has to “”breathe.”
Not all living things “breathe” in the same way that animals do — inhaling and exhaling. Plants, for example, do not breathe. However, the cells of all living things do take in and release gases. Children’s firsthand experience of the need to breathe and their observations of other animals may lead them to think that all living things have to breathe. The process where plants take in CO2 and release O2 during photosynthesis is sometimes likened to breathing, so children may equate it with breathing.
6. Growth is not a pre-requisite of life. One characteristic of life is a life span, which includes a period of growth. From a living beginning as a single cell, all life forms can be observed to grow — even organisms that are made of only one cell. Growth occurs as cells get bigger and, in multicellular organisms, as cells divide to form new cells. This idea may arise because children observe some living things when they are no longer growing. A full-grown plant, for example, may not appear to grow.
7. Objects like seeds, spores, eggs, and pupae are not alive, but they can give rise to living things. Because seeds, spores, eggs, and pupae appear to be “doing nothing,” many children think they’re dead or nonliving while at the same time believing that they can give rise to living things. Just as all cells come from an existing cell, all life comes from something that is alive — there is no “discontinuity” of life during a life span. Seeds, spores, eggs, and pupae represent the living beginnings of a life span and have the potential for growth, development, reproduction, and death. They also demonstrate the other characteristics of life. This makes them alive. Children may believe this because they do not observe any activity in these objects, and they can’t see the developing organism inside.
8. Plants and fungi are not alive.
Because plants and fungi don’t move, some children think they aren’t alive. Nonetheless, both plants and fungi demonstrate the characteristics of life. They are built from cells, have life spans, require matter and energy, respond to their environment, and carry the hereditary material DNA. Children who consider movement as a requirement for life may hold this idea. In this case animals may be considered to be the only things that are alive.
9. Plants have a different kind of life than animals.
Plants and animals differ in many ways. However, the characteristics of life apply equally to both groups of organisms. Each is made of cells, has a life span, uses matter and energy, responds to its environment, and carries the hereditary material DNA. Children may think this because the observable differences between plants and animals seem to make them “opposites” of each other. This also may be reinforced by placing the emphasis on differences while teaching about these groups of organisms.
Related Lessons & Activities