Biology Reference
In-Depth Information
Glossary
Allele
: Organisms often possess several versions of the same gene.
Each version is an allele. This is particularly the case in diploid
organisms in which there are two versions of the same gene each
carried by each homologous chromosome (see
Diploid
).
Antibody
: See
Immunology
.
Antigen
: See
Immunology
.
Aristotelism (the four causes):
According to Aristotle, there are
four kinds of cause in Nature: the 'material cause' provides the mat-
ter out of which a phenomenon is constituted or involved in the
ontogenesis of objects. This material has no form on its own; it is
incapable of creating anything of an ordered nature by itself. It
therefore has to be associated with the 'formal cause' which pro-
vides a form corresponding to the essence of the phenomenon or
thing. These two causes are however insufficient because there is an
absence of movement. The 'efficient cause' is the immediate motor
that produces phenomena. The 'final cause' is the underlying pur-
pose of any process, the finality of which is the production of the
essence or form of things.
Blastocoel
: See
Blastula
.
Blastula
: Early stage in the development of embryos characterised
by the appearance of a cavity known as the blastocoel.
211
