biology-dictionary_11-06-2009

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Somatic nervous system
The branch of the motor division of the vertebrate peripheral nervous system composed of
motor neurons that carry signals to skeletal muscles in response to external stimuli.
Somatoplasm
The protoplasm of a somatic cell.
Somatotropin
A hormone, produced by the pituitary gland, that stimulates protein synthesis and promotes
the growth of bone; also known as growth hormone.
Source habitat
A habitat where reproduction exceeds mortality and from which excess individuals disperse.
Southern blotting
A hybridization technique that enables researchers to determine the presence of certain
nucleotide sequences in a sample of DNA.
Spathe
A large leaf that surrounds the base of a flower cluster.
A leaflike bract that encloses or subtends a flower cluster or spadix, as in the jack-in-the-
pulpit and the calla.
Specialized
Of cells, having particular functions in a multicellular organism.
Speciation
The origin of new species in evolution.
Species
A particular kind of organism; members possess similar anatomical characteristics and have
the ability to interbreed.
Species diversity
The number and relative abundance of species in a biological community.
Species richness
The number of species in a biological community.
Species selection
A theory maintaining that species living the longest and generating the greatest number of
species determine the direction of major evolutionary trends.

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