- 업종: Biology
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Terrapsychology is a word coined by Craig Chalquist to describe deep, systematic, trans-empirical approaches to encountering the presence, soul, or "voice" of places and things: what the ancients knew as their resident genius loci or indwelling spirit. This perspective emerged from sustained ...
Makers and maintainers of protoplasm; the basic living unit of all organisms except viruses. The cells of organisms other than bacteria are eukaryotes those containing a defined nucleus in which chromosomes contain the DNA recipes from which cells synthesize protein. Cells know what to do and which genes to turn on because of what surrounding cells do in reference to a chemical-directional gradient. In organisms of greater complexity cells specialize into a variety of tissues.
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Industry:Biology
A form of nucleic acid organized into pairs of double-helix molecules packaged into chromosomes carrying the genetic code. The molecules are made of linked nucleotides units with a sugar, a phosphate, and one of four base chemicals adenine, thymine, guanine, and cytosine. These bases join like ladder rungs--always an A to a T and a C to a G--with the sugar-phosphate forming the outside "backbone" of the strand. The sequence of these nucleotides, with each group of three spelling one anino acid "codon," determines the kind of protein manufactured when translated by strands of RNA. (James Watson and Francis Crick discovered this structure in 1953.) RNA also aids in DNA's replication. Everything living carries the same gene code, one reason scientists are so confident we are all related biologically. Some DNA sequences are identical in humans and bacteria, a fact that underlines our common biological origins.
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Industry:Biology
A plant's reproductive organs that produce seeds for growing new plants. Flowers usually have vivid colors making them one of the most beautiful productions of nature.
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Industry:Biology
A daptive changes in the genetic characteristics of a population over time--but this adaptation is not necessarily “improvement.” This entry says "Evolution" and not "Evolutionary Theory" because evolution is not a theory anymore. Evolutionary operations and outcomes have been observed directly, today, as well as indirectly through field studies, DNA research, evidence-dating techniques, the fossil record, etc. The animal equipped with a new and helpful feature is likelier to live long enough to pass it down than an animal without it.
Elephants in China are more frequently born tuskless, now, due to pressure from poaching. See Speciation for an example of a family of Asian butterflies branching into different species today. Genetic mutations, which are rare and usually harmful, play less of a role in evolution than Darwin believed, and cultural forces that reinforce selection for certain characteristics a larger role. (See Natural Selection and Sexual Selection.) According to biologist Richard Dawkins, the eye has evolved independently at least forty times, echo location four times, the venomous sting ten times, electrolocation several times, flapping flight four times, jet propulsion twice, and sound production for social purposes too many times to count. See Convergent Evolution, Taxonomy.
Industry:Biology
Dans une cellule, l'organite qui contient le matériel génétique (ADN et chromosomes) ; Centre de contrôle de la cellule. Aussi : le centre d'un atome autour duquel les électrons orbitent.
Industry:Biology
Le passage de l'eau et des nutriments dans des membranes de cellules au lieu de par ingestion directe. Fait également référence à comment les objets convertir le rayonnement solaire qu'ils reçoivent en chaleur.
Industry:Biology
L'organe reproducteur femelle d'une fleur. Carpelles (feuilles portant les ovules) composent, et les étamines, pétales et sépales sonner. Une fleur sans étamines est un pistillées.
Industry:Biology
Organe reproducteur femelle multicellulaire en mousses, fougères et la plupart des gymnospermes. Normalement en forme de flacon, il correspond au pistil chez les angiospermes.
Industry:Biology
An organism that can double as an autotroph (produces its own food) or heterotroph (eats food produced by other organisms). Some tiny marine protozoans are mixotrophs.
Industry:Biology
An organism that makes its own food through photosynthesis (plants) or chemosynthesis (certain microorganisms). Primary producers form the foundation of the food web.
Industry:Biology