tropism(redirected from positive tropismnegative tropism)
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a growth response in a nonmotile organism elicited by an external stimulus, and either toward the stimulus (positive tropism) or away from it (negative tropism); used as a word element combined with a stem that indicates the nature of the stimulus (e.g., phototropism) or the material or entity for which an organism or substance shows a special affinity (e.g., neurotropism). See also taxis.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
tro·pism, positive tropismnegative tropism (trō'pizm),
The phenomenon, observed in living organisms, of moving toward (positive tropism) or away from (negative tropism) a focus of light, heat, or other stimulus; usually applied to the movement of a portion of the organism as opposed to taxis, the movement of an entire organism.
[G. tropē, a turning]
Farlex Partner Medical Dictionary © Farlex 2012
The turning or bending movement of an organism or a part of an organism in a particular direction in response to an external stimulus such as light or gravity.
tro′pic, tro·pis′tic adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
The phenomenon, observed in living organisms, of moving toward (positive tropism) or away from (negaive tropism) a focus of light, heat, or other stimulus; usually applied to the movement of a portion of the organism as opposed to taxis, the movement of an entire organism.
[G. tropē, a turning]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
tropismAn automatic movement made by an organism towards or away from a source of stimulation.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
tropisma bending growth movement in a plant either away from or towards a directional stimulus. Tropic movements are brought about by unequal growth on the two sides of an organ (such as the stem) brought about by unequal distributions of AUXIN. See PHOTOTROPISM, GEOTROPISM, THIGMOTROPISM, CHEMOTROPISM.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005