Science — page 6 of 132

13,110 terms including subtopics (0 terms filed directly here)

Subtopics

Science terms

  1. Ammonium One form of nitrogen that is usable by plants.
  2. amniocentesis A procedure for obtaining foetal cells for prenatal diagnosis by sampling the amniotic fluid from a pregnant mammal.
  3. Amnion The thin membrane that lines the fluid-filled sac in which the embryo develops in higher vertebrates, reptiles and birds.
  4. Amniotic fluid Liquid contents of the amniotic sac of higher vertebrates, containing foetal, but not maternal cells.
  5. amorph A mutation that abolishes gene function. Synonym: null mutation.
  6. Amorphous Semiconductor A non-crystalline semiconductor material that has no long-range order.
  7. AMOS Automatic Meteorological Observing System
  8. AMP Abbreviation for adenosine monophosphate.
  9. Amp-Hours A measure of the flow of current (in amperes) over one hour.
  10. Amperage The strength of an electric current measured in amperes. The amount of electric current flow, similar to the flow of water in gallons per minute (gpm).
  11. Ampere A unit of measure for an electrical current; the amount of current that flows in a circuit at an electromotive force of one Volt and at a resistance of…
  12. Ampere (amp) A unit of electric current or rate of flow of electrons. One volt across 1 ohm of resistance causes a current flow of 1 ampere.
  13. Amperometric Based on the electric current that flows between two electrodes in a solution.
  14. Amphibian A cold-blooded, smooth-skinned vertebrate of the class Amphibia, such as a frog, toad, or salamander, that characteristically hatches as an aquatic larva…
  15. amphidiploid A plant derived from doubling the chromosome number of an interspecific F1 hybrid. Naturally found hybrids of this sort are referred to as allopolyploid.
  16. amphimixis True sexual reproduction involving the fusion of male and female gametes and the formation of a zygote.
  17. ampicillin A penicillin-type antibiotic that prevents bacterial growth by interfering with synthesis of the cell wall.
  18. Ampicillin (beta-lactamase) An antibiotic derived from penicillin that prevents bacterial growth by interfering with cell wall synthesis.
  19. amplicon The product of a DNA amplification reaction. See: polymerase chain reaction.
  20. Amplification 1. Creation of many copies of a segment of DNA by the polymerase chain reaction. 2. Treatment (e.g.
  21. amplified fragment length polymorphism (Abbreviation: AFLP). A type of DNA marker, generated by the PCR amplification of restriction endonuclease treated DNA.
  22. Amplifier A device used to increase the strength of an analog signal
  23. Amplify To increase the number of copies of a DNA sequence, in vivo by inserting into a cloning vector that replicates within a host cell, or in vitro by…
  24. Amplitude The maximum magnitude of a quantity. Often used to refer to the maximum height of a wave.
  25. ampometric See: electrochemical sensor
  26. AMR acquisition management review.
  27. AMS 1. Air Mass - a body of air covering a relatively wide area and exhibiting horizontally uniform properties. 2. American Meteorological Society
  28. AMT Amount
  29. AMVER Automated Mutual Assistance Vessel Rescue System. A system operated by the U.S.
  30. AMVER/SEAS A software program created by the National Weather Service intended to efficiently generate AMVER and VOS reports as part of a cooperative effort.
  31. AMWUA Arizona Municipal Water Users Association.
  32. amylase (AM-il-aze) An enzyme that helps the body digest starches.
  33. amylolytic The capability of enzymatically degrading starch into sugars.
  34. amylopectin A polysaccharide comprising highly branched chains of glucose residues. The water-insoluble portion of starch.
  35. amylose A polysaccharide consisting of linear chains of 100-1000 glucose residues. The water-soluble portion of starch.
  36. anabolic pathway A pathway by which a metabolite is synthesized; a biosynthetic pathway.
  37. anabolism One of the two subcategories of metabolism, referring to the building up of complex organic molecules from simpler precursors.
  38. Anabranch A diverging branch of a river which re-enters the main stream.
  39. Anadromous Fish that live most of their adult life in saltwater but spawn in freshwater.
  40. Anadromous fish Fish that hatch in freshwater, migrate to the ocean to mature, then return to freshwater to spawn. An example is salmon.
  41. Anaerobe An organism that grows in the absence of oxygen. See Aerobe.
  42. Anaerobic An environment or condition in which molecular oxygen is not available for chemical, physical or biological processes.
  43. Anaerobic Bacteria Microorganisms that live in oxygen deprived environments.
  44. Anaerobic decomposition The breakdown of molecules into simpler molecules or atoms by microorganisms that can survive in the partial or complete absence of oxygen.
  45. Anaerobic Digester A device for optimizing the anaerobic digestion of biomass and/or animal manure, and possibly to recover biogas for energy production.
  46. anaerobic digestion Digestion of materials in the absence of oxygen. See: anaerobic respiration.
  47. Anaerobic Lagoon A holding pond for livestock manure that is designed to anaerobically stabilize manure, and may be designed to capture biogas, with the use of an…
  48. Anaerobic organism An organism that does not need oxygen to stay alive. See anaerobic.
  49. anaerobic respiration Respiration in which foodstuffs are partially oxidized, with the release of chemical energy, in a process not involving atmospheric oxygen.
  50. analog In chemistry, a substance that is similar, but not identical, to another.
  51. analog signal A signal, such as voice, that varies in a continuous manner.
  52. analogous Features of organisms or molecules that are superficially or functionally similar but have evolved in a different way or contain different compounds.
  53. Analysis A process in which anything complex is separated into simple or less complex parts.
  54. anaphase The stage of mitosis or meiosis during which the daughter chromosomes migrate to opposite poles of the cell (toward the ends of the spindle ).
  55. ANBURS Alphanumeric Backup Replacement System
  56. Anchor block. See thrust block.
  57. anchor gene A gene that has been positioned on both the physical map and the linkage map of a chromosome, and thereby allows their mutual alignment.
  58. Anchor Ice Submerged Frazil ice attached or anchored to the river bottom, irrespective of its formation.
  59. Anchor Ice Dam An accumulation of anchor ice which acts as a dam and raises the water level.
  60. Ancillary services Those services necessary to support the transmission of electric power from seller to purchaser, given the obligations of control areas and transmitting…
  61. Andesite Volcanic rock (or lava), characteristically medium dark in color and containing 54 to 62 percent silica and moderate amounts of iron and magnesium…
  62. androgen (AN-droh-jen) A type of hormone that promotes the development and maintenance of male sex characteristics.
  63. androgenesis Male parthenogenesis, i.e. the development of a haploid embryo from a male nucleus.
  64. Anemia (a-NEE-mee-a) A condition in which the number of red blood cells is below normal.
  65. Anemometer An instrument for measuring the force or velocity of wind; a wind gauge.
  66. Anemorumbograph Anemorumbograph Russian anemograph (recording anemometer) which is equipped with a device to record the wind direction in addition to wind speed.
  67. Anemorumbometer Anemorumbometer Russian anemometer combined with a vane to determine the wind direction.
  68. Aneroid Barometer An instrument for measuring atmospheric pressure in which a needle, attached to the top of an evacuated box, is deflected as changes in atmospheric…
  69. Aneuploid (an you ployd') describes an abnormal (not normal) amount of DNA in cells.
  70. Angels Radar echoes caused by birds, insects, and localized refractive index discontinuities.
  71. angiogenesis (AN-jee-oh-JEN-eh-sis) Blood vessel formation. Tumor angiogenesis is the growth of new blood vessels needed for tumors to grow.
  72. angiogenin One of the human angiogenic growth factors. In addition to stimulating (normal) blood vessel formation, angiogenin levels are correlated with placenta…
  73. angiosperm A division of the plant kingdom that includes all flowering plants, i.e. vascular plants in which double fertilization occurs resulting in development of…
  74. Angle of external friction (angle of wall friction) Angle between the abscissa and the tangent of the curve representing the relationship of shearing resistance to normal stress acting between soil and…
  75. Angle of Incidence In reference to solar energy systems, the angle at which direct sunlight strikes a surface; the angle between the direction of the sun and the…
  76. Angle of Inclination In reference to solar energy systems, the angle that a solar collector is positioned above horizontal.
  77. Angle of internal friction (angle of shear resistance) The angle between the axis of normal stress and the tangent to the Mohr envelope at a point representing a given failure-stress condition for solid…
  78. Angle of obliquity The angle between the direction of the resultant stress or force acting on a given plane and the normal to that plane.
  79. Angle of Reflection The angle at which a reflected ray of energy leaves a reflecting surface. It is measured between the outgoing ray and a perpendicular to the surface at…
  80. Angle of repose Angle between the horizontal and the maximum slope that a particular soil or geologic material assumes through natural processes.
  81. Angle of view The angle, both vertical and horizontal, between a viewer's line of sight and the landscape being viewed.
  82. Angle of wall friction Angle between the abscissa and the tangent of the curve representing the relationship of shearing resistance to normal stress acting between soil and…
  83. Angler-day The time spent fishing by one person for any part of a day.
  84. Angstrom A unit of length equal to 10-8 cm.
  85. Angstrom Unit A unit of length named for A.J. Angstome, a Swedish spectroscopist, used in measuring electromagnetic radiation equal to 0.000,000,01 centimeters.
  86. Angular resolution The smallest angular size that the instrument can resolve.
  87. Angular Size The size of an object as viewed from the earth. For example, the moon subtends (covers) an angle of 1/2 of a degree.
  88. Anhydrous A compound that does not contain water. For example, fuel ethanol is referred to as "anhydrous ethanol" because most of the water has been removed.
  89. Anhydrous Ethanol One hundred percent alcohol; neat ethanol.
  90. animal cell immobilization Entrapment of animal cells in some solid material in order to produce some natural product or genetically engineered protein.
  91. animal cloning See: cloning.
  92. animal model An animal with a disease either the same as or like a disease in humans. Animal models are used to study the development and progression of diseases and…
  93. Animal unit A unit of measure for rangeland livestock equivalent to one mature cow or five sheep or five goats, all over 6 months of age.
  94. Animal Unit (AU) (AU) A measurement of herd size used in the dairy industry. One animal unit is equal to 1000 pounds of animals. For example, a 1,200-pound cow equals 1.2 AU.
  95. Animal Unit Month (AUM) (AUM) A standardized unit of measurement of the amount of forage required by an animal unit for one month.
  96. Anion A negatively charged ion in an electrolyte solution, attracted to the anode under the influence of a difference in electrical potential. See cation.
  97. Anisotropic mass A mass having different properties in different directions at any given point.
  98. Anisotropy The difference in the property of a system with changes in direction. In this case, anisotropy refers to the difference in the temperature of the cosmic…
  99. Anneal The pairing of complementary DNA or RNA sequences, via hydrogen bonding, to form a double-stranded polynucleotide.
  100. Annex (functional) An emergency operations plan element that describes the jurisdiction's plan for functioning in that component area of activity during emergencies.