Notes

Chemotropism, movement or growth in response to chemicals
Geotropism (or gravitropism), movement or growth in response to gravity
Heliotropism, diurnal motion or seasonal motion of plant parts in response to the direction of the sun, (e.g. the sunflower)
Hydrotropism, movement or growth in response to water
Phototropism, movement or growth in response to lights or colors of light
Thermotropism, movement or growth in response to temperature
Electrotropism, movement or growth in response to an electric field
Thigmotropism, movement or growth in response to touch or contact
Exotropism, continuation of growth "outward," i.e. in the previously established direction
Ecotropism, limited host range (e.g. infects only one species or cell type)
Amphotropism, wide host range (e.g. infects many of entry into cells used by a given strain of HIV)
Neurotropism, a virus that preferentially infects the host's nervous system
Photoperiodism, is response to seasons



Chemo-tropism is the growth of organisms (or parts of an organism, including individual cells) such as bacteria and plants, navigated by chemical stimulus from outside of the organism or organisms part. The response of the organism or organism part is termed ‘positive’ if the growth is towards the stimulus or ‘negative’ if the growth is away from the stimulus.



Heliotropism, a form of tropism, is the diurnal motion or seasonal motion of plant parts (flowers or leaves) in response to the direction of the sun.



Hydrotropism (hydro- "water"; tropism "involuntary orientation by an organism, that involves turning or curving as a positive or negative response to a stimulus")[1] is a plant's growth response in which the direction of growth is determined by a stimulus or gradient in water concentration. A common example is a plant root growing in humid air bending toward a higher relative humidity level



Phototropism is the growth of organisms in response to a light stimulus. It is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs




Thermotropism or Thermotropic Movement is the movement of a plant or part of a plant in response to a change in temperature. A common example is the curling of Rhododendron leaves in response to cold temperatures




Electrotropism is a kind of tropism which results in growth or migration of an organism, usually a cell, in response to an exogenous electric field. Several types of cells such as nerve cells, muscle cells, fibroblasts, epithelial cells,[1] green algae, spores, and pollen tubes,[2] among others, have been already reported to respond by either growing or migrating in a preferential direction when exposed to an electric field.




Thigmotropism It is a directional growth movement of curvature which occurs in response to stimulus of contact. Thigmatotropism is found in twiners and tendrils



1 . Exotropism, continuation of growth "outward," i.e. in the previously established direction
Ecotropism, limited host range (e.g. infects only one species or cell type)
Amphotropism, wide host range (e.g. infects many of entry into cells used by a given strain of HIV)
Neurotropism, a virus that preferentially infects the host's nervous system
Photoperiodism, is response to season