Canadian Medical Guide > Biological Sciences > Biological Phenomena, Cell Phenomena, and Immunity > Plant Physiology > Tropism Terms and Definitions




Tropism

Medical Definition: The directional growth of an organism in response to an external stimulus such as light, touch, or gravity. Growth towards the stimulus is a positive tropism; growth away from the stimulus is a negative tropism. (From Concise Dictionary of Biology, 1990)
Guide Notes: directional growth toward or away from a stimulus
Tropism Categories.
Canadian Medical Guide Definition Gravitropism - The directional growth of organisms in response to gravity. In plants, the main root is positively gravitropic (growing downwards) and a main stem is negatively gravitropic (growing upwards), irrespective of the positions in which they are placed. Plant gravitropism is thought to be controlled by auxin (AUXINS), a plant growth substance. (From Concise Dictionary of Biology, 1990)
Canadian Medical Guide Definition Phototropism - The directional growth of organisms in response to light. In plants, aerial shoots usually grow towards light. The phototropic response is thought to be controlled by auxin (= AUXINS), a plant growth substance. (From Concise Dictionary of Biology, 1990)

Tropism Medical Definitions and Terms

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