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trace element
Any of a number of elements required by living organisms, in small amounts, to ensure normal growth, development, and maintenance. They do not include the basic elements of organic compounds (carbon, hydrogen, oxygen, and nitrogen) or the other major elements present in quantities greater than about 0.005% (calcium, phosphorus, potassium, sodium, chlorine, sulfur, and magnesium). Among the most important trace elements in terrestrial organisms are iron, manganese, zinc, copper, iodine, cobalt, molybdenum, selenium, chromium, and silicon (see elements, biological abundance). Because living things serve to locally concentrate trace elements, accumulations of these elements in rocks provide a biomarker which astrobiologists will be able to use in their search for extraterrestrial life.
Related category
• BIOCHEMISTRY
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