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 Introduction to Astronomy
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 Glossary: Climate Change
 Glossary: Astronomy
 Glossary: Life in Universe
 


    Glossary of Terms - A to F
    Index: A to F | G to L | M to R | S to Z


    abiotic - (a.)

    not involving or not produced by living organisms

    absorption lines - (n.)

    Any portion of the electromagnetic spectrum (including visible light) that is trapped by free atoms or molecules in the path of the radiation, thus reducing their transmission. In the climate context, this is important for the greenhouse effect since water vapor, carbon dioxide and methane absorb certain wavelengths of infrared radiation.

    adaptive radiation - (n.)

    The evolution of a species into a group of species, adapted to different niches.

    adenine (A) - (n.)

    One of the four nitrogenous bases in the nucleotides of DNA and RNA.

    adenosine triphosphate (ATP) - (n.)

    A compound present in all cells that provides energy derived from sunlight (in photoautotrophs), chemical reactions (in chemoautotrophs), or food (in heterotrophs) that, stored in its phosphate bonds, can be released to power cellular processes.

    aerobe - (n.)

    Organism capable of using molecular oxygen (O2) in aerobic respiration, either as a requirement to live (as in obligate aerobes) or as an energy-yielding process to supplement fermentation (as in facultative aerobes) : ~ See Also: complete aerobe; facultative aerobe; obligate aerobe.

    aerobic - (n.)

    A process occurring in the presence of oxygen.

    aerobic respiration - (n.)

    The oxygen-consuming, energy-yielding process carried out by almost all eukaryotes and diverse prokaryotes; "breathing."

    aerobiosis - (n.)

    A mode of life that requires oxygen. ~ See Also: anaerobiosis.

    age of evident life - (n.)

    Informal name for the Phanerozoic Eon.

    alanine - (n.)

    One of the twenty amino acids commonly present in proteins of living systems.



    Index: A to F | G to L | M to R | S to Z


    alcohol - (n.)

    A compound composed of an alkyl group and a hydroxyl group; HOOCH.

    alga - (n.)

    Any of diverse types of eukaryotic photoautotrophic single-celled protists, such as phytoplankton or many-celled seaweeds

    ALH84001 - (n.)

    The 1.9-kg meteorite claimed to contain evidence of past martian microbial life, named for where and when it was found (Allan Hills ice field, Antarctica, in 1984) together with its assigned sample number (001).

    allele - (n.)

    One of two or more variants of the same gene. ~ See Also: Gene.

    allotropes - (n.)

    Different forms of the same element in the same physical state.

    ambiguity reduction - (n.)

    The process by which the ambiguous codon assignments of the early genetic code, in which one codon could specify more than one amino acid, were replaced by more precise assignments. Currently, each codon specifies only one amino acid, although an amino acid can be specified by more than one codon.

    amino acid - (n.)

    A small molecule (monomer) containing an amino group (-NH2) at one end and a carboxylic acid group (-COOH) at the other that can be linked to other amino acids to form a protein. Amino acids are fundamental building blocks of life. More than 80 amino acids are known, but only about 20 occur naturally in living organisms.

    ammonia - (n.)

    The chemical compound NH3.

    anaerobe - (n.)

    An organism, such as many bacteria or archaea, that can live in the absence of free oxygen. Anaerobes may be facultative, indifferent to the presence or absence of oxygen, or obligate. Obligate anaerobes are actually poisoned by oxygen. In some cases their ancestors may never have lived in an environment with oxygen, and such obligate anaerobes may be descendants of very primitive organisms.

    angiosperms - (n.)

    Flowering, fruit-producing plants. ~ See Also: Flower, Fruit, Gymnospenns.

    angular momentum - (n.)

    A measure of the mass, radius, and rotational velocity of a rotating or orbiting body. In the simple case of an object in circular orbit, the angular momentum is equal to the mass of the object times its distance from the center of the orbit times its orbital speed.



    Index: A to F | G to L | M to R | S to Z


    anhydride - (n.)

    A substance from which water has been removed.

    anion - (n.)

    A negatively charged ion.

    anoxic - (n.)

    With reference to the complete absence of molecular oxygen (O2).

    anoxygenic photosynthesis - (n.)

    The non-oxygen-producing photoautotrophy of photosynthetic bacteria.

    antibiotic - (n.)

    A soluble substance, produced by a mold or bacterium, that inhibits growth of other microorganisms.

    anticodon - (n.)

    The sequence of three adjacent nucleotides in a tRNA molecule that is complementary to a codon on mRNA.

    antimetabolite - (n.)

    A compound that inhibits the synthesis of nucleic acids.

    antioxidants - (n.)

    Chemicals so easily oxidized that they protect other substances from oxidation; reducing agents.

    apex chert - (n.)

    A fossiliferous horizon of the Apex Basalt, a 3,465-Ma-old geologic unit of Western Australia.

    archaea (pl.) - (n.)

    archaeon (sing.) one of the three current major domains of life, the others being the eukaryotes and the eubacteria. These bacteria-like organisms, all single-celled and lacking nuclei, are often, but not always, are found in extreme environments.

    archaebacteria - (n.)

    An old name for a member of the archaea; use "archaea" instead.



    Index: A to F | G to L | M to R | S to Z


    archean era - (n.)

    The older era of the Precambrian Eon, extending from Earth's formation 4,550 Ma ago to the beginning of the Proterozoic 2,500 Ma ago; together, the Archean and Proterozoic Eras comprise the Precambrian Eon.

    aromatic hydrocarbon - (n.)

    Any hydrocarbon that contains a benzene ring.

    asexual - (a.)

    Nonsexual.

    aspartic acid - (n.)

    One of the twenty amino acids commonly present in proteins of living systems.

    ATP - (n.)

    Adenosine triphosphate, a combination of ADP and phosphate linked by a pyrophosphate bond : The central conveyer of metabolic energy, thanks to its two terminal pyrophosphate bonds. ~ See Also: ADP, AMP, Phosphorylation, Pyrophosphate.

    autotrophy - (n.)

    Literally, self-feeding : the capacity of an organism to obtain its essential nutrients by synthesizing non organic materials such as carbon dioxide, molecular nitrogen or nitrate, sulfate, and so on from the environment, rather than by consuming organic materials; photosynthetic green plants and chemosynthetic bacteria are examples of autotrophic organisms. ~ See Also: Chemoautotrophy, Heterotrophy, Phototrophy.

    axon - (n.)

    The filament whereby a neuron exerts an effect. ~ See Also: Dendrite, Neuron, Synapse.

    bacteria - (n.)

    Superkingdom of organisms, all single-celled and lacking nuclei, distinct from Archaea and Eucarya.

    bacterial domain - (n.)

    Together with Archaea and Eucarya, one of three superkingdomlike primary branches of the Tree of Life.



    Index: A to F | G to L | M to R | S to Z


    bacterium - (n.)

    Any of an extremely flexible class of microscopic life whose members have a variety of structures, come singly or in colonies, live just about anywhere, and derive energy from whatever source is available.

    banded iron formation (BIF) - (n.)

    Chemically deposited cherty sedimentary rock, usually thinly bedded and containing more than 15% iron.

    basalt - (n.)

    A type of rock resulting from the cooling of lava.

    base - (n.)

    A proton acceptor.

    base pairing - (n.)

    The phenomenon, based on chemical complementarity, whereby adenine (A) binds to uracil (U) or thymine (T), and guanine (G) to cytosine (C), in nucleic acids.

    BIF - (n.)

    Banded iron formation.

    big bang theory - (n.)

    A cosmological model, in which the universe was once compressed to infinite density and has been expanding ever since. Originally a term used by unbelieving scoffers, now as widely accepted as the model itself.

    biochemical - (n.)

    Any of a large number of chemical compounds made by a living system, composed commonly of carbon, hydrogen, oxygen, nitrogen, sulfur, and/or phosphorus (CHONSP).

    biochemistry - (n.)

    A study of the chemistry of living systems.

    biomarkers - (n.)

    Chemical remnants of cells found preserved in rocks, 'chemical fossils'. The term usually, but not always, refers to hydrocarbons derived from the components of cells.

    biomass - (n.)

    The total mass of plants and animals; in energy studies, usually means plant material used as a source of fuel.



    Index: A to F | G to L | M to R | S to Z


    biosphere - (n.)

    The part of the Earth on which life is possible. The biosphere is now known to extend thousands of feet down into deep rock formations.

    black smokers - (n.)

    High temperature springs of water on the ocean floor, which appear black because of suspended particles of iron sulfide.

    blue-green algae - (n.)

    (cyanobacteria); these bacteria-like organisms are the inventors of the kind of photosynthesis that produces free oxygen. This invention seems to have taken place only once, for the blue-green algae are also the ancestors of the chloroplasts that are found in higher plants and that are responsible for the photosynthesis on which we all depend for life.

    buffer - (n.)

    A compound that reacts with either acid or base to keep the pH of a solution essentially constant.

    calcareous - (n.)

    Containing or composed of calcium carbonate.

    calcite - (n.)

    A mineral, calcium carbonate, CaCO3.

    calorie - (n.)

    A measure of energy in the form of heat, originally corresponding to the amount of heat required to raise the temperature of 1 gram of water by 1° C.

    Cambrian explosion - (n.)

    The name given to the abrupt appearance of the major animal phyla in the visible or macro-fossil record early in the Cambrian period.

    Cambrian period - (n.)

    The earliest geologic period of the Phanerozoic Eon of Earth's history, extending from 543 to 495 Ma ago.

    carbohydrate - (n.)

    A carbon-, hydrogen-, and oxygen-containing organic polymeric compound composed of sugar subunits.

    carbon fixation - (n.)

    The metabolic incorporation of carbon into an organic compound.



    Index: A to F | G to L | M to R | S to Z


    carboxyl group - (n.)

    -COOH, characteristic of all organic acids.

    catabolism - (n.)

    The metabolic process in which complex compounds are broken down to simpler substances.

    catalysis - (n.)

    The process whereby a substance (catalyst) facilitates a chemical reaction without itself being consumed in the process. ~ See Also: Enzyme, Ribozyme.

    cation - (n.)

    A positively charged ion.

    cell - (n.)

    The structural unit of plant and animal life.

    cell membrane - (n.)

    The lipid bilayer that encloses a cell.

    cell nucleus - (n.)

    The organelle (small structure) within a cell that contains the genetic material of the cell.

    cellulose - (n.)

    A polymeric organic compound composed of glucose subunits abundant in the walls of plant cells.

    cell wall - (n.)

    A solid shell, made of murein in eubacteria and of a different material in archaebacteria, that surrounds most prokaryotic cells. ~ See Also: Archaebacteria, Eubacteria, Murein.

    chemical bond - (n.)

    A linkage between two atoms of a molecule or between atoms of neighboring molecules, often by shared electrons.

    chemical equation - (n.)

    A before-and-after description in which chemical formulas and coefficients represent a chemical reaction.



    Index: A to F | G to L | M to R | S to Z


    chemical symbol - (n.)

    The abbreviation, consisting of one or two letters, that stands for an element.

    chemoautotrophy - (n.)

    The capacity of an autotrophic (self-feeding) organism to derive the energy required for its growth from certain chemical reactions (e.g., methanogenesis) rather than from photosynthesis; some bacterial forms are chemoautotrophic organisms.

    chemosynthesis - (n.)

    Synthesis of organic compounds using energy derived from chemical reactions.

    chert - (n.)

    Rock composed of precipitated silicon dioxide (microcrystalline quartz, SiO2 ). A common example is flint.

    chirality - (n.)

    The property of molecules that exist in two forms whose spatial configurations are mirror images of each other : Examples are L- and D-amino acids. ~ See Also: Amino acid, Protein.

    chlorophyll - (n.)

    A porphyrin derivative related to heme but with magnesium replacing iron; the green, light-absorbing substance that serves as the principal catalyst of phototrophy. ~ See Also: Heme, Phototrophy.

    chloroplast - (n.)

    The central, light-utilizing organelles of all eukaryotic phototrophs : Evolutionarily derived from endosymbiotic cyanobacteria, chloroplasts are dense, oblong particles, about one ten-thousandth of an inch in size, surrounded by two membranes and filled with stacks (grana) of flat, membranous pouches (thylakoids) bearing membrane embedded photosystems I and II, together with associated electron-transfer chains. ~ See Also: Chlorophyll, Cyanobacteria, Electron-transfer chain, Endosymbiont.

    CHONSP - (n.)

    Abbreviation for the biogenic elements carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus.

    chordates - (n.)

    Animals possessing a notochord at least at some stage of development : They include all vertebrates and a few lower forms. ~ See Also: Notochord.

    chromatography - (n.)

    A chemical technique in which organic compounds can be separated using columns or sheets of filtering material (see geochromatography).

    chromosome - (n.)

    A cell structure containing genetic DNA : In eukaryotes, chromosomes are situated in the nucleus and are detectable as compact rods during mitosis : Prokaryotic chromosomes are circular and have a simpler structure. ~ See Also: Mitosis.



    Index: A to F | G to L | M to R | S to Z


    clade - (n.)

    Group of organisms all descended from a single common ancestor.

    clone - (n.)

    A population of cells derived by successive divisions from a single ancestral cell.

    coacervates - (n.)

    Structures, the existence of which was originally suggested by Aleksandr Oparin, that may have been important in the origin of life. As Oparin envisioned them, they were globules surrounded by membranes that enclosed and protected a variety of organic molecules. Think oily ocean foam.

    codon - (n.)

    A triplet of bases in messenger RNA coding for an amino acid or (3 out of the total of 64 triplet combinations) for a chain termination signal. ~ See Also: Amino acid, Anticodon : Base pairing, Genetic code, Messenger RNA, Translation.

    complete aerobe - (n.)

    Any of various plant and plantlike organisms, including cyanobacteria, capable both of oxygen production (by oxygenic photosynthesis) and oxygen consumption (by aerobic respiration).

    conglomerate - (n.)

    A coarse-grained sedimentary rock formed of rounded fragments less than 2 mm across and cemented in a finer-grained matrix; the consolidated equivalent of gravel.

    conjugation - (n.)

    The phenomenon whereby two bacterial cells join temporarily and exchange genetic material. ~ See Also: Pilus, Plasmid.

    continental drift - (n.)

    The slow movement of continental and oceanic plates probably caused by convection in the underlying asthenosphere, measured in a few centimeters per year, that has resulted in massive alterations of the features of the Earth's crust over geologic time. Colliding plates can generate mountain ranges and upwellings of the mantle can push plates apart to produce ocean basins. Also called plate tectonics.

    convection - (n.)

    The transport of energy by fluid motions occurring in gases, in liquids, or in semi rigid material such as the earth's mantle. These motions are usually driven by the buoyancy of heated material, which tends to rise while cooler material descends.



    Index: A to F | G to L | M to R | S to Z


    core - (n.)

    Central part of Earth, having a radius of about 2100 miles.

    cosmogony - (n.)

    The study of the origin of the universe, usually applied in particular to the origin of the solar system.

    covalent bond - (n.)

    A bond formed between atoms by the sharing of electrons.

    Cretaceous period - (n.)

    The youngest of the three geologic periods of the Mesozoic Era of Earth's history, extending from approximately 145 to 65 Ma ago.

    crust - (n.)

    the outermost layer of the Earth. The crust on the continents is thicker (between 30-50 km) than that of the ocean basins (thickness 5-10 km).

    cyanobacteria - (n.)

    Phototrophic bacteria capable of using light energy to extract hydrogen from water, with the production of molecular oxygen : Ancestral to chloroplasts. ~ See Also: Chlorophyll, Chloroplast.

    cyst - (n.)

    Microscopic saclike body having a robust wall that in some microalgae, protozoans, and other protists serves as a resting stage in the life cycle preceding sexual reproduction.

    cytoplasm - (n.)

    The total content of a eukaryotic cell, with the exception of the nucleus.

    cytosine - (n.)

    A pyrimidine base found in both DNA and RNA. ~ See Also: Base pairing, Deoxyribonucleic acid, Pyrimidines, Ribonucleic acid, Thymine, Uracil.

    cytoskeleton - (n.)

    The set of internal structures, made of proteins, that support eukaryotic cells. ~ See Also: Actin, Clathrin, Microtubule, lhbulin.

    Darwinian struggle - (n.)

    The competition among organisms during natural selection.



    Index: A to F | G to L | M to R | S to Z


    deoxyribonucleic acid (DNA) - (n.)

    The genetic information-containing molecule of cells and a number of viruses, a double-stranded nucleic acid made up of nucleotides that contain a nitrogenous base (adenine, guanine, thymine, or cytosine), deoxyribose sugar, and a phosphate group.

    development, biologic - (n.)

    The sequence of processes involved in growth from a fertilized egg to an adult organism.

    Devonian period - (n.)

    A geological period of the Phanerozoic Eon of Earth's history, extending from 410 to 360 Ma ago.

    dextro isomer - (n.)

    A "right-handed" isomer.

    diatom - (n.)

    Any of a taxonomic group of unicellular algae occurring in marine or fresh water, each having a cell wall made of two halves impregnated with silica.

    diploid - (n.)

    A cell or organism possessing two sets of chromosomes such that every gene (except those governing gender) is present as two copies.

    dipole - (n.)

    A molecule that has a positive end and a negative end.

    DNA - (n.)

    Deoxyribonucleic acid, a long chain of molecules that contains the genetic information of life.

    domain - (n.)

    A superkingdomlike primary branch of the Tree of Life.

    double helix - (n.)

    The characteristic structure of DNA, made of two intertwined, complementary strands stabilized by base pairing. ~ See Also: Base pairing, Deoxyribonucleic acid.

    ecologic specialist - (n.)

    An organism well adapted to an ecologically limited habitat, such as any of most eukaryotes.



    Index: A to F | G to L | M to R | S to Z


    ecology - (n.)

    The science that deals with the interrelations among organisms inhabiting a common environment and between these organisms and the environment.

    ecosystem - (n.)

    The complex of a biologic community and its environment viewed as an interactive unit.

    Ediacaran fauna - (n.)

    A latest Proterozoic-age assemblage of soft-bodied many-celled animals, the oldest fauna known.

    egg cell - (n.)

    The female gamete. ~ See Also: Fertilization, Gamete, Sexual reproduction, Sperm cell.

    enantiomers - (n.)

    The different forms of chiral molecules.

    endosymbiont - (n.)

    A cell, most often of prokaryotic type, adopted as a stable component of a eukaryotic cell : Several cell organelles, including chloroplasts, mitochondria, and, perhaps, peroxisomes and hydrogenosomes, are derived from endosymbiotic bacteria. ~ See Also: Chloroplast, Hydrogenosome, Mitochondrion, Peroxisome.

    endosymbiotic hypothesis - (n.)

    The concept that organelles (such as mitochondria and chloroplasts) of eukaryotic cells are evolutionary descendants of free-living bacteria that established endosymbiosis with an ancestral eukaryotic host cell.

    enzyme - (n.)

    A protein capable of catalyzing a biochemical reaction.

    ester - (n.)

    The substance arising by combination, with loss of water, of the carboxyl group of an organic acid with the hydroxyl group of an alcohol, with formation of an ester bond, -O-CO-. ~ See Also: Carboxyl group, Hydroxyl group, Thioester.

    Eubacteria - (n.)

    "true" bacteria, as distinguished from archaea. Like archaea they are single-celled organisms that possess chromosomes but lack a cell nucleus. They can be distinguished from archaea because many of their genes are very different from their archaeal equivalents.

    eukaryote - (n.)

    Any of a taxonomic group (the Eucarya) of organisms composed of one or more nucleus-containing cells (in contrast to the Bacteria and Archaea); any member of the Eucaryal domain such as a protist, fungus, plant, or animal.



    Index: A to F | G to L | M to R | S to Z


    eukaryotes - (n.)

    Living organisms—comprising protists, plants, fungi, and animals, including humans—made of large cells having a fenced-off nucleus and a cytoplasm containing cytomembranes, cytoskeletal elements, and, most often, mitochondria, peroxisomes, and, in algae and plants, chloroplasts. ~ See Also: Chloroplast, Cytomembrane system, Cytoskeleton, Mitochondrion, Nucleus, Peroxisome, Prokaryotes.

    evolution - (n.)

    Change over time in the morphology and physiology of species of organisms; or of any object, such as stars; or of ideas; etc.

    evolutionary convergence - (n.)

    The independent evolutionary development of the same trait in two or more separate lines.

    evolutionary distance - (n.)

    The degree of evolutionary relatedness between two biologic lineages.

    evolutionary stasis - (n.)

    Lack of evolutionary change over geologically long periods.

    evolutionary theory - (n.)

    Any theory in which observed phenomena are thought to have arisen as a result of natural processes, requiring no outside intervention or sudden changes.

    exon - (n.)

    Any of many parts of a gene that encodes information that can be translated into protein or functional RNA.

    extremeophile - (n.)

    Microbes such as many archaeans that tolerate exceptionally high-temperature acidic environments.

    facultative aerobe - (n.)

    Any of various prokaryotes, usually bacterial, capable of aerobic respiration but that can also grow in the absence of molecular oxygen (O2) by anaerobic metabolism.



    Index: A to F | G to L | M to R | S to Z


    feed (antenna feed, line feed) - (n.)

    In a reflecting antenna system, the device that converts a guided (by wire, cable, or other wave guide) electromagnetic wave intc? an electromagnetic radiation field, and vice versa, when reciprocity theorem holds as it so often does. Commonly, feeds are some form of horn antenna, but they may be dipole arrays or their.

    ferric iron - (n.)

    Oxidized iron, having a valence of +3 as in hematite, Fe2+3O3-2

    ferrous iron - (n.)

    Reduced iron, having a valence of +2 as in pyrite, Fe+2S-

    fertilization - (n.)

    The combination of a male gamete, or sperm cell, with a female gamete, or egg cell. ~ See Also: Egg cell, Gamete, Sexual reproduction, Sperm cell.

    filament - (n.)

    (a) A feature of the solar surface seen in Ha as a thin, dark wavy line. A filament is a prominence projected on the solar disk. (b) In microbiology, a collective term for the cylindrical external sheath and cellular internal trichome of a filamentous prokaryote.

    filtergram - (n.)

    A photograph taken through a filter that passes only a very narrow band of wavelengths; usually applied to solar photographs.

    fireball - (n.)

    An exceptionally bright meteor. ~ See Also: bolide.

    first law of thermodynamics - (n.)

    Energy is neither created nor destroyed.

    fission, nuclear - (n.)

    The splitting of an atomic nucleus.

    flagellum - (n.)

    Plural: flagella : In prokaryotes, a rigid, helical rod, made of protein, that propels the cell by axial rotation : In eukaryotes, a long, waving motor appendage constructed from microtubules and other components according to the same architecture as cilia. ~ See Also: Cilium, Undulipodia.

    flare - (n.)

    A rapid eruption of material from the surface of the sun or other star.



    Index: A to F | G to L | M to R | S to Z


    fluorescence - (n.)

    The emission of light at a particular wavelength following excitation of the electron by absorption of light at another, shorter, wavelength.

    flux - (n.)

    The amount of something (such as energy) passing through a surface per unit time.

    focal length - (n.)

    The distance from a lens or mirror to the point at which rays from an object at infinity are focused.

    foraminferan - (n.)

    Any of a protozoal order (Foraminifera) of marine rhizopods usually having a calcareous shell perforated with minute holes for protrusion of slender pseudopodia.

    force - (n.)

    In physics, something that can or does cause a change of momentum, measured by the rate of change of momentum with time.

    force field - (n.)

    A way of describing phenomena that result from action at a distance, that is, even though objects are not touching.

    formation, geologic - (n.)

    The fundamental unit in the stratigraphic classification of rocks, a definable, mappable body of igneous, sedimentary, or metamorphic rock.

    fossil fuels - (n.)

    Coal, petroleum, and natural gas.

    fossil record - (n.)

    Remnants or traces of organisms of past geological ages embedded in Earth's crust.

    Fraunhofer lines - (n.)

    The absorption lines of a solar or other stellar spectrum.

    free-living - (n.)

    With reference to metabolic independence, said of an organism that is neither parasitic nor symbiotic.



    Index: A to F | G to L | M to R | S to Z


    free radical - (n.)

    A reactive neutral chemical species that contains an unpaired electron.

    frequency - (n.)

    The rate (in units of Hertz, or cycles per second) at which electromagnetic waves pass a fixed point. The frequency, usually designated , is related to the wavelength  and the speed of light c by  = c/.

    fruit - (n.)

    The seed-containing structure that develops from a flower after fertilization in angiosperms. ~ See Also: Angiosperms, Double fertilization, Flower.

    fuels - (n.)

    Substances that burn readily with the release of significant amounts of energy.

    fungus - (n.)

    Plant of the Thallophyta subkingdom, which lacks chlorophyll and ranges in form from a single cell to massed bodies, including yeasts, molds, and mushrooms.

    fusion - (n.)

    The amalgamation of nuclei into heavier nuclei.

    fusion reaction - (n.)

    A nuclear reaction in which atomic nuclei combine to form more massive nuclei.



    Index: A to F | G to L | M to R | S to Z

 


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