Around two dozen of the 92 naturally
occurring chemical elements are essential to various kinds of biological
life. Most rare elements on Earth are not needed by life (exceptions
being selenium and iodine), while a few common ones (aluminum and
titanium) are not used. Most organisms share element needs, but there
are a few differences between plants and animals. For example ocean
algae use bromine but land plants and animals seem to need none. All
animals require sodium, but some plants do not. Plants need boron and
silicon, but animals may not (or may need ultra-small amounts).
Just six elements—carbon, hydrogen, nitrogen, oxygen, calcium, and
phosphorus—make up almost 99% of the mass of a human body . In addition
to the six major elements that compose most of the human body, humans
require smaller amounts of possibly 18 more.
occurring chemical elements are essential to various kinds of biological
life. Most rare elements on Earth are not needed by life (exceptions
being selenium and iodine), while a few common ones (aluminum and
titanium) are not used. Most organisms share element needs, but there
are a few differences between plants and animals. For example ocean
algae use bromine but land plants and animals seem to need none. All
animals require sodium, but some plants do not. Plants need boron and
silicon, but animals may not (or may need ultra-small amounts).
Just six elements—carbon, hydrogen, nitrogen, oxygen, calcium, and
phosphorus—make up almost 99% of the mass of a human body . In addition
to the six major elements that compose most of the human body, humans
require smaller amounts of possibly 18 more.
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