Structural Biochemistry/Taxis

Definition
A taxis is an innate behavioural response to a directional stimulus (a stimulus from a particular direction) for which the organism either moves toward (positive taxis) or away from (negative taxis) the stimulus, called orientation movement. For example, organisms in the genus of flagellate protozoa Euglena moves towards a light source. Here the directional stimulus is light, and the orientation movement is toward it. This is positive taxis to light, more specifically positive phototaxis.

There are four different forms of taxis:
 * chemotaxis
 * mechanotaxis
 * haptotaxis
 * durotaxis

Reference
http://www.chemistrydaily.com/chemistry/Taxis