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  2. Biological roles of the elements - Wikipedia

    en.wikipedia.org/wiki/Biological_roles_of_the...

    Examples include iron, essential to hemoglobin; and magnesium, essential to chlorophyll. Some elements are essential only to certain taxonomic groups of organisms, particularly the prokaryotes. For instance, the lanthanide series rare earths are essential for methanogens. As shown in the following table, there is strong evidence that 19 of the ...

  3. List of unsolved problems in biology - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Homochirality is an obvious characteristic of life on Earth, yet extraterrestrial samples contain largely racemic compounds. [7] It is not known whether homochirality existed before life, whether the building blocks of life must have this particular chirality, or whether life must be homochiral at all.

  4. List of fictional elements, materials, isotopes and subatomic ...

    en.wikipedia.org/wiki/List_of_fictional_elements...

    The real element 99, einsteinium, has no such qualities. Element 115 Ufology, various works Widely known within the sci-fi and UFO community; since, according to ufologist Bob Lazar, it is used by alien engines to generate anti-gravity and propulsion. The real element 115 is moscovium, a synthetic element with an extremely short half-life ...

  5. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are thought on the basis of good evidence to be necessary for life. [1] All of the mass of the trace elements put together (less than 10 grams for a human body) do not add up to the body mass of magnesium, the least common of the 11 non-trace ...

  6. CHNOPS - Wikipedia

    en.wikipedia.org/wiki/CHNOPS

    Graphic representation of carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. CHNOPS and CHON are mnemonic acronyms for the most common elements in living organisms. . "CHON" stands for carbon, hydrogen, oxygen, and nitrogen, which together make up more than 95 percent of the mass of biological system

  7. Hypothetical types of biochemistry - Wikipedia

    en.wikipedia.org/wiki/Hypothetical_types_of...

    The possibility of life-forms being based on "alternative" biochemistries is the topic of an ongoing scientific discussion, informed by what is known about extraterrestrial environments and about the chemical behaviour of various elements and compounds. It is of interest in synthetic biology and is also a common subject in science fiction.

  8. Carbon-based life - Wikipedia

    en.wikipedia.org/wiki/Carbon-based_life

    The carbon cycle is a biogeochemical cycle that is important in maintaining life on Earth over a long time span. The cycle includes carbon sequestration and carbon sinks. [4] [5] Plate tectonics are needed for life over a long time span, and carbon-based life is important in the plate tectonics process. [6]

  9. List of chemical elements - Wikipedia

    en.wikipedia.org/wiki/List_of_chemical_elements

    118 chemical elements have been identified and named officially by IUPAC.A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z).