Tactic/Kinetic Responses

• Give an example of a simple, mobile organism?

  Woodlice

  Earthworms
• What do simple mobile organisms have?

  Simple responses to keep them in a favourable environment

  Their response can either be TACTIC or KINETIC
• Tactic responses are called?

  taxes
• Describe taxes?


  The organisms move towards towards or away from a directional stimulus eg light
• Describe kineses ?


  The organisms' movement is affected by a non-directional stimulus eg humidity
• kinetic responses are called?

  kineses
• Example of a woodlice taxes?

  Woodlice show a tactic response to light (phototaxis)- they move AWAY FROM A LIGHT SOURCE

  • helps them survive as it keeps them concealed under stones during the day (where they're safe from predators) and keeps them in damp conditions (reduces water loss)
• Example of a Woodlice kinetic response/kineses?

  Woodlice show a kinetic response to humidity

  High humidity- move slowly and turn less often, so that they stay where they are. As air gets drier, move faster & turn more often- so that they move into a new area

  • this response increases the chance that a woodlouse will move to an area with higher humidity
  • this improves the survival chances of the organism- reduces their water loss and helps keep them concealed