biology-dictionary_11-06-2009

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Chaparral
A scrubland biome of dense, spiny evergreen shrubs found at midlatitudes along coasts
where cold ocean currents circulate offshore; characterized by mild, rainy winters and long,
hot, dry summers.
Character displacement
A phenomenon in which species that live together in the same environment tend to diverge
in those characteristics that overlap; exemplified by Darwin's finches.
Chelonia
An order of the Reptilia, subclass Anapsida, including the turtles, terrapins, and tortoises.
Chemical bond
An attraction between two atoms resulting from a sharing of outer-shell elctrons or the
presence of opposite charges on the atoms; the bonded atoms gain complete outer electron
shells.
Chemical equilibrium
In a reversible chemical reaction, the point at which the rate of the forward reaction equals
the rate of the reverse reaction.
Chemical reaction
A process leading to chemical changes in matter; involves the making and/or breaking of
chemical bonds.
Chemiosmosis
The production of ATP using the energy of hydrogen-ion gradients across membranes to
phosphorylate ADP; powers most ATP synthesis in cells.
Chemiosmotic coupling
The mechanism by which ADP is phosphorylated to ATP in mitochondria and chloroplasts.
The energy released as electrons pass down an electron transport chain is used to establish
a proton gradient across an inner membrane of the organelle; when protons subsequently
flow down this electrochemical gradient, the potential energy released is captured in the
terminal phosphate bonds of ATP.
Chemoautotroph
An organism that needs only carbon dioxide as a carbon source but that obtains energy by
oxidizing inorganic substances.

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