Hint: Chemotropism is the growth of organisms caused by the external chemical stimuli outside the plant or organism body. The chemotropism is of two types namely positive chemotropism and negative chemotropism. It is mostly seen in bacteria, plants, and fungi.
Complete answer: The chemo- means relating to chemicals and tropism means chemotropism. Chemotropism is the growth of organisms by chemical stimuli from outside of the organism. It is mostly seen in bacteria, plants, and fungi. A chemical gradient can influence the growth of the organism in a positive or negative way. There are two types of chemotropism: positive chemotropism and negative chemotropism. A positive chemotropism is one, in which the growth response is towards the stimulus whereas a negative chemotropism is when the growth response is away from the stimulus.
Chemotropism can be observed during the growth of the pollen tube towards the ovules. The roots growing towards useful minerals are also exhibiting chemotropism, which is positive chemotropism. There are some cases or situations where the roots grow away from harmful acids and chemical substances, and these cases are an example of negative chemotropism. It is not the same as chemotaxis and chemokinesis. Chemotaxis pertains to the directional movement of an organism or a living motile cell in response to certain diffusible chemicals in the environment. The response of a cell or an organism towards the soluble chemicals that leads to a random movement is called chemokinesis. Examples of chemotropism are the growth of the pollen tube towards the ovule. Conversion of the flower into a fruit.
Note: Different types of tropism in plants are: - Phototropism is the response to light. Geotropism is the response to gravity. Chemotropism is the response to particular substances. Hydrotropism is the response to water. Thigmotropism is the response to mechanical stimulation. Traumatropism is the response to wound lesions. Galvanotropism or electrotropism is the response to electric current.