Explain the different types of tropisms with examples. (5mk)
Answers
Types :
In plants (and bacteria)
Example of gravitropism in the remains of a cellar of a Roman villa in the Archeologic Park in Baia, Italy
Aerotropism, growth of plants towards or away from a source of oxygen
Chemotropism, movement or growth in response to chemicals
Electrotropism, movement or growth in response to an electric field
Exotropism, continuation of growth "outward," i.e. in the previously established direction
Geotropism (or gravitropism), movement or growth in response to gravity
Apogeotropism, negative geotropism
Heliotropism, diurnal motion or seasonal motion of plant parts in response to the direction of the sun, (e.g. the sunflower)
Apheliotropism, negative heliotropism
Hydrotropism, movement or growth in response to water; in plants, the root cap senses differences in water moisture in the soil, and signals cellular changes that causes the root to curve towards the area of higher moisture[2]
Prohydrotropism, positive hydrotropism
Hygrotropism, movement or growth in response to moisture or humidity
Magnetotropism, movement or growth in response to magnetic fields
Orthotropism, movement or growth in the same line of action as the stimulus
Plagiotropism, movement or growth at an angle to a line of stimulus such as gravity or light
Phototropism, movement or growth in response to lights or colors of light
Aphototropism, negative phototropism
Skototropism, negative phototropism of vines
Thermotropism, movement of growth in response to temperature
Thigmotropism, movement or growth in response to touch or contact
In viruses
Amphotropism, wide host range (e.g. infects many species or cell types)
Ecotropism, limited host range (e.g. infects only one species or cell type)
HIV tropism, the means of entry into cells used by a given strain of HIV
Neurotropism, a virus that preferentially infects the host's nervous system