Types of Tropisms The Biological Phenomenon

Published: 09th May 2011
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Tropism is a term that is derived from the original Greek word trope that is basically a biological phenomenon and related to plant world though at times the terminology is also used for the animal world.





Tropism Features





Major features of tropism are


It is basically a biological phenomenon that indicates the growth or the turning movements in the biological organisms.


The movement is opposed to the nastic movements that are non-dimensional.


Such movements are usually in response to the environmental stimulus.


Tropism is essential related to plant world though at times it is used for the animal world as well.





Reasons of Tropisms





Various elements result in tropisms in plants and other biological species. One of the major reasons is viruses and pathogens affecting the host tropism or cell tropism. In such cases, the tropism will refer to the ways of evolution of viruses or pathogens in targeting specific host species or specific cell types within the species. Tropisms are always related to the stimulus. For instance; phototropism can be the reaction to light. Tropisms could also be positive or negative, the former refereeing to the movements towards the stimulus while the latter refers to moving away from it.





Tropisms Components





Typically associated with plants though not totally restricted to them, tropisms are the events where the organism becomes capable of motility or directed physical movement in response to specific stimulus. A directional response is called "taxis" while the non-directional response is called "Kenesis".





Types of Tropisms





Some of the main types of tropisms are


Chemotropism referring to movement in response to chemicals.


Hydrotropism referring to movement or growth in response to water.


Thermotropism refers to movement or growth in response to environmental temperature.


Geotropism that refers to growth in response to gravity.


Phototropism referring to movement in response to colors of light.


Helitropism referring to movement or growth in response to sunlight.


Thigmotropism that refers to movement or growth in response to touch or contact.


Host tropism or cell tropism that refers to response to pathogens.


Others are ecotropism, amphotropism, neurotropism, and phtoperiodism.





One thing is common in all cases. Tropism is always with reference to movement of plants or biological elements.











State university website is the right place to approach for finding out information on subjects like types of Tropisms with references to the Cambridge Encyclopedia Volumes. Besides the site also offers a host of information on different U.S universities offering academic and technical courses on the subject.

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