Responses

• What is a stimulus?

  a detectable change in the internal and external environment that leads to a response in the organism
• What is taxis?

  directional response where the whole organism moves towards or away from stimulus
• What is an example of taxis?

  • whole organism moves away from sunlight so that they do not lose water, which is fatal
  • this is negative phototaxis
• What is kinesis?

  the rate at which as organism changes direction in response to a stimulus
• What is an example of kinesis?

  • woodlice turning sharply when entering an unfavourable environment so that it returns to a favourable environment
  • when it has been in an unfavourable environment for a long time, rate of turning decreases and moves in straight line to leave area
• What is tropism?

  directional response where part of the organism moves to stimuli
• What is an example of tropism?

  • leaves of plants moving towards sunlight
  • but the stem remains and doesn't move