Cladophylls
A photosynthetic branch or portion of a stem that resembles and functions as a leaf, as in
the asparagus. Also called cladode.
Clasper
Any of the appendages of the male of certain insects and crustaceans that are used during
copulation to hold the female.
Class
A taxonomic grouping of related, similar orders; category above order and below phylum.
Classical conditioning
A type of associative learning; the association of a normally irrelevant stimulus with a fixed
behavioral response.
Classification
The systematic grouping of organisms into categories on the basis of evolutionary or
structural relationships between them.
A division or category in a classifying system.
Cleavage
The process of cytokinesis in animal cells, characterized by pinching of the plasma
membrane; specifically, the succession of rapid cell divisions without growth during early
embryonic development that converts the zygote into a ball of cells.
Cleavage furrow
The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old
metaphase plate.
Cline
Variation in features of individuals in a population that parallels a gradient in the
environment.
Clitoris
A small elongated erectile organ at the anterior part of the vulva, homologous with the
penis, present in female
Cloaca
A common opening for the digestive, urinary, and reproductive tracts in all vertebrates
except most mammals.
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