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natural selection
natural selection (‘survival of the fittest’) A complex process in which the total environment determines which members of a species survive to reproduce and so pass on their genes to the next generation. This need not necessarily involve a struggle between organisms....
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loudspeaker
loudspeaker or speaker, device used to convert electrical energy into sound. It consists essentially of a thin flexible sheet called a diaphragm that is made to vibrate by an electric signal from an amplifier . The vibrations create sound waves in the air around the speaker. In a dynamic speak...
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retrovirus
retrovirus type of RNA virus that, unlike other RNA viruses, reproduces by transcribing itself into DNA. An enzyme called reverse transcriptase allows a retrovirus's RNA to act as the template for this RNA-to-DNA transcription. The resultant DNA inserts itself into a cell's DNA and is reproduced ...
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absolute music
absolute music term used for music dependent on its structure alone for comprehension. It is the antithesis of program music . It is not associated with extramusical ideas or with a pictorial or narrative scheme of emotions, nor does it attempt to reproduce sounds in nature. Hence it is always ins...
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Thomas Deloney
Thomas Deloney , c.1543-c.1600, English ballad writer, fiction writer, and pamphleteer. He was a silk weaver. Deloney's chief works are three prose narratives— Jack of Newbury, Thomas of Reading, and The Gentle Craft (all c.1597)—relating to the clothier's, weaver's, and shoemaker's c...
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festoon
festoon sculptured or painted architectural or interior ornament consisting of a garland of leaves, flowers, or fruit, or some combination of these, held by ribbons or folds and draped at the ends. When a festoon hangs down from only one end, it is called a drop, but when it hangs from both ends it...
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spore
spore term applied both to a resistant or resting stage occurring among various unicellular organisms (especially bacteria) and to an asexual reproductive cell produced by many unicellular plants and animals and by all plants that undergo an alternation of generations. A spore is typically a cell...
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vegetative propagation
vegetative propagation the ability of plants to reproduce without sexual reproduction, by producing new plants from existing vegetative structures. Some plants, such as the Canada thistle and most bamboos, send out long underground stems that produce new plants, often at considerable distances from...
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Appian
Appian , fl. 2d cent., Roman historian. He was a Greek, born in Alexandria. He held various offices in Alexandria, was an advocate in Rome, and then imperial procurator in Egypt. His history of the Roman conquests, from the founding of Rome to the reign of Trajan, is more a collection of monographs ...
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Mastigophora
Mastigophora , phylum of unicellular heterotrophic protozoans of the kingdom Protista . Most of the approximately 1,500 species of Mastigophora are propelled by one or more flagella, and members of the group are sometimes referred to as flagellates. Some have pseudopodia, temporary armlike protrusi...
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