Science terms starting with H

545 terms

  1. herbaceous plants Non-woody species of vegetation, usually of low lignin content such as grasses.
  2. Herbicide A chemical that kills plants.
  3. herbicide resistance The ability of a plant to remain unaffected by the application of a herbicide.
  4. Herbicide-tolerant crop Crop plants that have been developed to survive application(s) of one or more commercially available herbicides by the incorporation of certain gene(s)…
  5. Herbivore Animal that feeds on plants.
  6. Herd Area (HA) Following passage of the Wild Free-Roaming Horses and Burros Act (WFRHBA) in 1971, the Bureau of Land Management was directed to identify areas where wild…
  7. Herd Management Area (HMA) An area that has been designated for management of wild horses and/or burros.
  8. Hereditary cancer Cancer that occurs due to the inheritance of an altered gene within a family. See also: sporadic cancer
  9. heredity Resemblance among individuals related by descent; transmission of traits from parents to offspring.
  10. heritability The degree to which a given trait is controlled by inheritance, as opposed to being controlled by non-genetic factors.
  11. heritable genetic effects Genetic damage caused by an external agent such as radiation, which manifests itself in the gene carrier and is capable of being passed on to succeeding…
  12. hermaphrodite 1. An animal that has both male and female reproductive organs, or a mixture of male and female attributes. 2.
  13. Herpetofauna Amphibian and reptile species including frogs, toads, salamanders, turtles, lizards, and snakes.
  14. Hertz A measure of the number of cycles or wavelengths of electrical energy per second; U.S. electricity supply has a standard frequency of 60 hertz.
  15. Hertz (Hz) The unit of measurement of frequency, equivalent to one cycle per second.
  16. hES cell Human embryonic stem cell; a type of pluripotent stem cell.
  17. heteroallele A gene having mutations at two or more different sites.
  18. Heterochromatin Dark-stained regions of chromosomes thought to be for the most part genetically inactive.
  19. Heteroduplex A double-stranded DNA molecule or DNA-RNA hybrid, where each strand is of a different origin.
  20. heteroduplex analysis The use of the electrophoretic mobility of to estimate the degree of non-homology between the sequences of the two strands.
  21. heterogametic Producing unlike gametes with regard to the sex chromosomes. In mammals, the XY male is heterogametic, and the XX female is homogametic.
  22. Heterogeneity See: genetic heterogeneity.
  23. heterogeneous nuclear RNA (Abbreviation: hnRNA ). Large RNA molecules, which are found in the nucleus of a eukaryotic cell and the precursors of mRNA and other RNA molecules.
  24. Heterogeneous nuclear RNA (hnRNA) The name originally given to large RNA molecules found in the nucleus, which are now known to be unedited mRNA transcripts, or pre-mRNAs. (See RNA.)
  25. Heterojunction A region of electrical contact between two different materials.
  26. heterokaryon A cell with two or more different nuclei as a result of cell fusion. See: synkaryon.
  27. Heterologous From a different source.
  28. heterologous probe A DNA probe that is derived from one species and used to screen for a similar DNA sequence from another species.
  29. heterologous protein See: recombinant protein.
  30. heteroplasmy A condition in which two genetically different organelles are present in the same cell. The equivalent to heterozygous in the context of nuclear genes.
  31. heteroploid Cells with nuclei containing chromosome numbers other than diploid.
  32. heteropyknosis The property of certain chromosomes, or of their parts, to remain more dense during the cell cycle and to stain more intensely than other chromosomes or…
  33. heterosis See: hybrid vigour.
  34. heterotroph Organism non capable of self-nourishment utilizing carbon dioxide or carbonates as the sole source of carbon and obtaining energy from radiant energy or…
  35. heterotrophic (adj.) See: heterotroph.
  36. Heterozygosity The presence of different alleles at one or more loci on homologous chromosomes.
  37. Heterozygote An individual with non-identical alleles for a particular gene or genes. The condition is termed "heterozygous". Opposite: homozygote.
  38. heterozygous (adj.) See: heterozygote.
  39. hexose Any of various simple sugars that have six carbon atoms per molecule (e.g. glucose, mannose, and galactose.)
  40. Hfr High-frequency recombination strain of Escherichia coli; in these strains, the F factor (plasmid) is integrated into the bacterial chromosome.
  41. HGH See Human growth hormone.
  42. HI High- In meteorology, a region of high pressure; also known as anticyclone.
  43. Hibernacula Caves or other structures used by bats for hibernation.
  44. HIC Hydrologist In Charge
  45. High (abbrev. HI)- In meteorology, a region of high pressure; also known as anticyclone.
  46. High Clouds These clouds have bases between 16,500 and 45,000 feet in the mid latitudes. At this level they are composed of primarily of ice crystals.
  47. High dam A dam over 300 feet high. See low dam and medium-height dam.
  48. high efficiency particulate air filter See: HEPA filter.
  49. High Electron Mobility Transistor (HEMT) This is a particular kind of transistor that is especially appropriate for use in microwave amplifiers.
  50. High Energy Event In solar-terrestrial terms, flares (class two or more) with outstanding Centimetric Bursts and SID.
  51. High Frequency (HF) The portion of the radio frequency spectrum between between 3 and 30 MHz
  52. High hazard A downstream hazard classification for dams in which more than 6 lives would be in jeopardy and excessive economic loss (urban area including extensive…
  53. High Latitudes With specific reference to zones of geomagnetic activity, "high latitudes" refers to 50º to 80º geomagnetic.
  54. High liquefaction potential Refers to the susceptibility of soils to liquefy when subjected to sudden loading, such as intense ground shaking from an earthquake.
  55. High Risk (of severe thunderstorms) Severe weather is expected to affect more than 10 percent of the area. A high risk is rare, and implies an unusually dangerous situation and usually the…
  56. High Seas Forecast (HSF) - Marine forecasts for the major oceans of the world. In this context, major gulfs or seas (e.g.
  57. High Surf Large waves breaking on or near the shore resulting from swells spawned by a distant storm.
  58. High Surf Advisory A High Surf Advisory is issued when breaking wave action poses a threat to life and property within the surf zone. High surf criteria vary by region.
  59. High Surf Warning A High Surf Warning is issued when breaking wave action results in an especially heightened threat to life and property within the surf zone.
  60. high throughput screening Automated systems designed to process large numbers of assays, especially in the context of genotyping.
  61. High Wind Sustained wind speeds of 40 mph or greater lasting for 1 hour or longer, or winds of 58 mph or greater for any duration.
  62. High Wind Advisory This product is issued by the National Weather Service when high wind speeds may pose a hazard. The criteria for this advisory varies from state to state.
  63. High Wind Warning This product is issued by the National Weather Service when high wind speeds may pose a hazard or is life threatening.
  64. High Wind Watch This product is issued by the National Weather Service when there is the potential of high wind speeds developing that may pose a hazard or is life…
  65. High-Intensity Discharge Lamp A lamp that consists of a sealed arc tube inside a glass envelope, or outer jacket.
  66. High-level clouds High-level clouds Cirrus, Cirrocumulus and Cirrostratus are high-level clouds.
  67. High-pressure gate A gate consisting of a rectangular leaf encased in a body and bonnet and equipped with a hydraulic hoist for moving the gate leaf.
  68. High-Pressure Sodium Lamp A type of High-Intensity Discharge (HID) lamp that uses sodium under high pressure as the primary light-producing element.
  69. High-Speed Stream In solar-terrestrial terms, a feature of the solar wind having velocities that are about double average solar wind values.
  70. High-throughput sequencing A fast method of determining the order of bases in DNA. See also: sequencing
  71. Higher heating value Quantity of heat liberated by the complete combustion of a unit volume or weight of a fuel assuming that the produced water vapor is completely condensed…
  72. Higher Heating Value (HHV) The maximum heating value of a fuel sample, which includes the calorific value of the fuel (bone dry) and the latent heat of vaporization of the water in…
  73. Higher Lubricity The ability to reduce friction—usually in fuel pumps and fuel injectors.
  74. Highly conserved sequence A DNA sequence that is very similar in several different kinds of organisms. Scientists regard these cross species similarities as evidence that a…
  75. Highly discordant land use Refers to development that is at variance with the existing condition of the land. It might also be described as incongruous.
  76. Hinge Crack Crack caused by significant changes in water level.
  77. Hirschman-Herfindahl Index (HHI) Market share analysis The sum of the squares of the market shares of firms competing in a market. HHI is a commonly accepted measure of market concentration.
  78. Hirschsprung's disease A congenital disorder in which part of the colon lacks nerve cells and therefore is unable to relax.
  79. histocompatibility The degree to which tissue from one organism is tolerated by the immune system of another organism.
  80. histocompatibility complex See: major histocompatibility complex.
  81. Histocompatible A tissue or organ from a donor (the person giving the organ or tissue) that will not be rejected by the recipient (the patient in whom the tissue or organ…
  82. histoglobulin The peptides present on the surface of nucleate cells, responsible for the differences between genetically non-identical individuals that cause rejection…
  83. histology (his-TAH-loh-jee) The study of tissues and cells under a microscope.
  84. histone A type of protein found in chromosomes. Histones bind to DNA, help give chromosomes their shape, and help control the activity of genes.
  85. Historic The time period after the appearance of written records. In the New World, this generally refers to the time period after the beginning of European…
  86. Historic Area An area or building in which historic events occurred, or one which has special value due to architectural or cultural features relating to the heritage…
  87. Historic floodplain An area larger than the 100-year floodplain.
  88. Historic properties Any prehistoric or historic districts, sites, buildings, structures, or objects included in, or eligible for inclusion in, the National Register of…
  89. Historic resources Material remains and the landscape alterations that have occurred since the arrival of Euro-Americans.
  90. Histosol Wet organic soils, such as peats and mucks.
  91. HLA One of a group of proteins found on the surface of white blood cells and other cells that play an important part in the body's immune response to foreign…
  92. HLS Hurricane Local Statement
  93. HMD (Hemispheric Map Discussion)- This discussion is issued once a day around 1 PM EST (2 PM EDT) and is primarily intended to provide insight into the…
  94. HND Hundred
  95. hnRNA See Heterogeneous nuclear RNA.
  96. Hoar Frost A deposit of interlocking crystals formed by direct sublimation on objects, usually those of small diameter freely exposed to the air, such as tree…
  97. Hoarfrost Hoarfrost A deposit of interlocking ice crystals (hoar crystals) formed by direct sublimation on objects, usually those of small diameter freely exposed…
  98. Hodograph A polar coordinate graph which shows the vertical wind profile of the lowest 7000 meters of the atmosphere.
  99. HOE A shovel that digs by pulling a broom-and-stick-mounted bucket toward itself.
  100. Hoechst dye A dye used to identify hematopoietic stem cells (HSCs).