Living things take materials in from the environment as well as give materials out. This is a characteristic of living things, since non-living things do not interact with the environment in this way.
What sorts of materials are exchanged?
The sorts of materials taken into the body and given out to the environment depend on the type of living thing you are investigating. There is a huge range of living things, all with very different requirements. However, what all living things have in common is that they all take materials in from the environment and they all give materials back to the environment.
Let's look at the materials that humans exchange with the environment - what are they and why does it happen?
Materials in and out of the human body
What sorts of materials are given out by your body?
