Taxis and Tropism
Stimulation is the process of inducing any living organisms to show some response. Reaction is the movement which is shown by an organism in response to the source of stimulus. This note explains what taxis and tropism is with their examples.
Summary
Stimulation is the process of inducing any living organisms to show some response. Reaction is the movement which is shown by an organism in response to the source of stimulus. This note explains what taxis and tropism is with their examples.
Things to Remember
- Stimulation is the process of inducing any living organisms to show some response.
- Reaction is the movement which is shown by an organism in response to the source of stimulus.
- The whole body movement shown by the organism in response to the source of stimulus is called taxis. An organism if attracted towards the source of stimulation then it is positive taxis otherwise its negative taxis.
- The movement of organism in response to light, as a source of stimulus, is called photo taxis.
- The movement shown by an organism in response to chemicals, as a source of stimulus is called chemo taxis.
- The movement of certain body part, not the whole body, of an organism due to some stimulus is called tropism. It may be positive and negative.
- The movement of certain body part of organism in response to light is called photo tropism.
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Taxis and Tropism
Stimulation:
The process of inducing any living organisms to show some response is called stimulation. The physical source which allow to show response is called source of stimulation.
Reaction:
The movement which is shown by an organism in response to the source of stimulus is called reaction.
Taxis and Tropism:
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Taxis:
The whole body movement shown by the organism in response to the source of stimulus is called taxis. Taxis may be positive or negative. When an organism is attracted (moves) towards the source of stimulus then that is called positive taxis. When an organism escape (moves) away from the source of stimulus then that movement is called negative taxis.Tasix takes place only in animals. Examples of taxis:- Phototaxis: The movement of organisms in response to light, as a source of stimulus, is called phototaxis. Movement of insects towards the light is positive phototaxis butmovement of cockroach away from light is negative phototaxis.
- Chemotaxis: The movement shown by an organism in response to chemicals, as a source of stimulus is called chemotaxis. Movement of ants toward sugar is positive chemotaxis but movement of mosquito away from burning coil is negative chemotaxis.
- Phototaxis: The movement of organisms in response to light, as a source of stimulus, is called phototaxis. Movement of insects towards the light is positive phototaxis butmovement of cockroach away from light is negative phototaxis.
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Tropism:
The movement of certain body part, not the whole body, of an organism due to some stimulus is called tropism. Tropism may be positive or negative. When an organism's body part moves towards the source of stimulus then that is called positive tropism. When an organism's body part moves away from the source of stimulus then that movement is called negative tropism. Tropism takes place only in plants.
Examples of tropism:
- Phototropism: The movement of the certain body part of an organism in response to light is called phototropism. E.g. Root of the plant moves into the ground away from the sun is negative phototropism (this can also be an example of positive geotropism) and movement of shoot towards the light source is positive phototropism.
Some Examples of Taxis and Tropisms:
| No. | Stimuli | Type | Nature | Examples |
| 1 | Light | Phototaxis | Positive | Movement of algae towards light |
| Negative | Movement of earthworm against light | |||
| 2 | Chemicals | Chemotaxis | Positive | Antherozoids of fern move Malic acid |
| Negative | Mosquitoes fly away from anti mosquito mat | |||
| 3 | Heat | Thermotropism | Positive | Opening of lotus in sun's heat |
| Negative | Closing of lilies during day | |||
| 4 | Gravity | Geotropism | Positive | Growth of roots into the ground |
| Negative | Growth of the shootsaway from the ground | |||
| 5 | Water | Hydrotropism | Positive | Movement of roots towards water |
| Negative | Sporangiospores of many molds grow away from a moist substratum | |||
| 6 | Contact | Thigmotropism | Positive | Whapping of tendrils of climbers |
| Negative | Collapsing of leaves of mimosa plant |
Lesson
Stimulation And Reaction
Subject
Science
Grade
Grade 10
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