biology-dictionary_11-06-2009

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Seconday meristem
In flowering plants, meristems develop from cells that suspend their ability to divide, and
resume this activity later. Such meristems are known as secondary meristems. These cells
give rise to permanent secondary tissues.
Secondary cell wall
The innermost wall of a plant cell that is deposited after cell elongation has enclosed.
Secondary compound
A chemical compound synthesized through the diversion of products of major metabolic
pathways for use in defense by prey species.
Secondary consumer
A member of the trophic level of an ecosystem consisting of carnivores that eat herbivores.
Secondary growth
The increase in girth of the stems and roots of many plants, especially woody, perennial
dicots.
Secondary immune response
The immune response elicited when an animal encounters the same antigen at some later
time. The secondary immune response is more rapid, of greater magnitude, and of longer
duration than the primary immune response.
Secondary productivity
He rate at which all the heterotrophs in an ecosystem incorporate organic material into new
biomass, which can be equated to chemical energy.
Secondary rachis
A large compound leaf of a palm.
Secondary sex characteristics
Characteristics of animals that distinguish between the two sexes but that do not produce
or convey gametes; includes facial hair of the human male and enlarged hips and breasts of
the female.
Secondary structure
The localized, repetitive coiling or folding of the polypeptide backbone of a protein due to
hydrogen bond formation between peptide linkages.

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