Chemical substances artificially composed

In the chapter opener, you considered how the terms "natural" and "chemical" are used inaccurately. A natural substance is a substance that occurs in nature and is not artificial. A chemical is any substance that has been made using chemical processes in a laboratory. A chemical can also be defined as any substance that is composed of atoms. This definition covers most things on Earth. Go to the web site above, and click on Web Links to find out where to go next. Look up some nafura/poisons, pesticides, and antibiotics that are produced by animals, plants, and bacteria. Then look up some beneficial chemicals that have been synthesized by humans. Make a poster to illustrate your findings. 

The membrane barrier test is composed of two components, a synthetic macromolecular bio-barrier and a chemical detecting system (CDS). The basis of the test method is that it detects membrane barrier damage caused by corrosive test substances after the application of the test substance to the surface of the artificial membrane barrier presumably by the same mechanism(s)... 

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