<descriptor thcode="2"><thesaurus thcode="2" name="USGS Thesaurus" scope="Topics and methods of scientific study carried out by USGS, with product types, scientific disciplines, geologic time, and types of institutional structure and activities.  Broad and shallow, used to help people find scientific information." creator="U.S. Geological Survey" rights="Public domain" edition="2.0" date="2020-01-09" codetype="number" prefix="topic" uri="https://www2.usgs.gov/science/USGSThesaurus" tblname="term" nonpref="nonpref" relterm="relterm" root_code="1" contact="pschweitzer"><category><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/></category><altlabel><altlabel>USGSThesaurus</altlabel><altlabel>USGSThesaurus</altlabel></altlabel></thesaurus><term thcode="2" code="843" name="organisms" parent="1174" scope="Living individuals that grow, reproduce, and die."/><uf><usefor name="biological organisms"/></uf><bt><term thcode="2" code="1174" name="topics" parent="1" scope="Themes, subjects, and concerns for which USGS information resources are relevant."/><term thcode="2" code="1" name="Categories" scope="Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."/></bt><nt><term thcode="2" code="29" name="algae" parent="843" scope="Chlorophyll-bearing primarily aquatic nonvascular species that have no true roots, stems, or leaves; most algae are microscopic, but some species can be as large as vascular plants."/><term thcode="2" code="45" name="animals" parent="843" scope="Multi-celled organisms of the kingdom Animalia with eukaryotic cells (cells with distinct nuclei containing genetic material and bounded by thin membranes) that are heterotrophic (obtaining energy from organic substances produced by other organisms)."/><term thcode="2" code="56" name="archaea" parent="843" scope="Microscopic organisms of the domain Archaea living on a diet of hydrogen and carbon dioxide, once thought to be bacteria, and often inhabiting extreme environments, such as thermal vents and hot springs, extremely alkaline and acidic waters, hypersaline water, and anoxic habitats."/><term thcode="2" code="76" name="bacteria" parent="843" scope="Single celled microorganisms, beneficial or pathogenic, without a nuclear membrane."/><term thcode="2" code="420" name="fungi" parent="843" scope="Immobile organisms of the kingdom Fungi that lack chlorophyll and that obtain nutrients from other dead or living organisms. Fungi reproduce by spores and include yeasts, molds, smuts, and mushrooms."/><term thcode="2" code="647" name="lichens" parent="843" scope="Plants that are composed of a fungus and an alga growing together symbiotically and often found growing on rocks or tree trunks."/><term thcode="2" code="909" name="plants (organisms)" parent="843" scope="Organisms which belong to the plant kingdom. Commonly multicellular, they produce food through photosynthesis."/><term thcode="2" code="940" name="protists" parent="843" scope="Unicellular eukaryotes (organisms possessing nucleated cells) with affinities to both plants and animals. Classed in the Protista or Potoctista kingdom, they include protozoans, foraminifera, radiolarians, fungi and some algae."/><term thcode="2" code="1280" name="viruses" parent="843" scope="Very small particles visible only with an electronic microscope. Considered to be complex molecules and not living organisms, these are often causes of disease in plants, animals, and bacteria."/></nt><rt><term thcode="2" code="650" name="life sciences" parent="1019" scope="Branches of science that study living and fossil organisms."/><term thcode="2" code="841" name="organism groupings (non-taxonomic)" parent="1174" scope="Used for categories of living organisms that are not taxonomic and that include species from more than one taxonomic group."/></rt></descriptor>