Glossary ❮ 319chymotrypsin Enzyme that cuts protein bonds in
the small intestine.
ciliaStructures that beat in rhythmical waves to carry
foreign particles and mucus away from the lungs.
circadian rhythmA physiologic cycle that occurs in
time increments that are roughly equivalent to the
length of a day.
class I histocompatibility antigens The surface of all
the cells of the human body, except for red blood
cells, have these antigens, which are slightly differ-
ent for each individual. The immune system
accepts any cell that has the identical match for
this antigen as friendly. Anything with a different
major histocompatibility complex is foreign.
class II histocompatibility antigens Antigens found
on the surface of the immune cells of the body.
These antigens play a role in the interaction
between the cells of the immune system.
classical conditioning Type of associative learning
that Ivan Pavlov demonstrated with his experi-
ments involving salivation in dogs.
cleavage divisions Developing embryo divides;
cytoplasm is distributed unevenly to the daughter
cells while the genetic information is distributed
equally.
cleavage furrowGroove formed in animal cells
between the two daughter cells; this groove
pinches together to complete the separation of the
two cells after mitosis.
climax communityFinal stable stage at the comple-
tion of a succession cycle.
clumped dispersion Scenario in which individuals
live in packs that are spaced out from each other.
codominance Both alleles express themselves fully in
a heterozygous organism.
codonA triplet of nucleotides that codes for a par-
ticular amino acid.
coefficient of relatedness Statistic that represents
the average proportion of genes that two individu-
als have in common.
coelomFluid-filled body cavity found between the
body wall and the gut that has a lining and is
derived from the mesoderm.
coelomates Animals that contain a true coelum.
coenocytic fungi Fungi that do not contain septae.
coevolution The mutual evolution between two
species, which is exemplified by predator–prey
relationships.
coleoptile Protective structure found around a grass
seedling.
collenchyma cells Live plant cells that provide flexi-
ble and mechanical support.
commensalism One organism benefits from the rela-
tionship while the other is unaffected.
community A collection of populations of species in
a given geographic area.
competent Describes a cell that is ready to accept
foreign DNA from the environment.
competitionBoth species involved are harmed by this
kind of interaction. The two major forms of compe-
tition are intraspecific and interspecific competition.
competitive inhibition Condition in which an
inhibitor molecule resembling the substrate binds
to the active site and physically blocks the sub-
strate from attaching.
complementA protein that coats cells that need to
be cleared, stimulating phagocytes to ingest them.
compoundsTwo or more elements combined to
form an entity.
conduction Process by which heat moves from a
place of higher temperature to a place of lower
temperature.
conifersGymnosperm plants whose reproductive
structure is a cone.
conjugationThe transfer of DNA between two
bacterial cells connected by appendages called
sex pili.
conservative DNA replication The original double
helix of DNA does not change at all; it is as if the
DNA is placed on a copy machine and an exact
duplicate is made. DNA from the parent appears
in only one of the two daughter cells.
convection Heat transfer caused by airflow.
convergent charactersCharacters are convergent if
they look the same in two species, even though the
species do notshare a common ancestor.
convergent evolution Two unrelated species evolve
in a way that makes them moresimilar. They both
respond the same way to some environmental
challenge, bringing them closer together.
cork cambiumArea that produces a thick cover for
stems and roots. It produces tissue that replaces
dried-up epidermis lost during secondary growth.
cork cells Cells produced by the cork cambium that
die and form a protective barrier against infection
and physical damage.http://www.ebook3000.com