Responses

Responses

Animal
1. Taxis is a directional response to stimulus.
  1. Positive
    1. Movement is towards the stimulus.
  2. Negative
    1. Movement is away from the stimulus.
  3. Examples
    1. Phototaxis (Light)
      1. Maggots use negative phototaxis to move away from light to avoid exposure and dryness.
      2. Single celled algae use positive phototaxis to move towards light to photosynthesis.
  4. Chemotaxis (chemicals)
    1. Male moths use positive chemotaxis when flying towards a pheromone
2. Kinesis is a response to a changing stimulus by changing the amount of activity.
  1. Orthokinesis
    1. the speed of movement varies with the intensity of the stimulus.
  2. Klinokinesis
    1. the rate of turning depends on the intensity of the stimulus.
  3. Results in random movements.
    1. It is designed to bring the organism back into favourable conditions.
  4. Example
    1. In dry environments woodlice move quickly and don't turn much which increases their chance moving out of the area.
      1. If by chance, they find themselves in a humid environment , they slow down and increase the rate of turning. This tend to keep them in a humid area.
Plants
1. Tropism is a directional growth responses to stimulus.
  1. Positive
    1. Growing towards the stimulus
  2. Negative
    1. Growing away from the stimulus
2. Example
  1. Phototaxis (Light)
    1. Plants shoot grow towards the light so their leaves are in the favourable position to absorb sunlight.
    2. Plants root grow away from the light and towards gravity to absorb more minerals ions.

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	Created by prettypriyaz over 10 years ago