Edexcel IGCSE Biology

Revision Notes

1.1.5 Living Organisms: Movement & Control


  • Movement is an action by an organism causing a change of position or place
  • The movement of an organism from place to place is called locomotion
  • Plants cannot move from place to place but can change their orientation
    • For example, sunflowers track the sun and so change their orientation throughout the day

Movement in plants, IGCSE & GCSE Biology revision notes
Sunflowers track the sun throughout the day


  • Living organisms must control their internal environment in order to keep conditions within required limits
  • This is called homeostasis

Homeostasis in humans

  • Thermoregulation refers to the control of body temperature
  • The optimum human body temperature is 37°C
    • If body temperature increases e.g. during exercise, mechanisms for control will be initiated to return the temperature back to the optimum
    • Mechanisms include sweating or vasodilation
  • Other homeostatic mechanisms in humans include glucoregulation (control of blood glucose levels) and osmoregulation (control of water levels)

Thermoregulation in humans, IGCSE & GCSE Biology revision notes
Thermoregulation is an example of homeostasis required to maintain a body temperature of 37°C

Homeostasis in plants

  • Plants use transpiration to maintain a suitable temperature
  • Water evaporates from the stomata on the underside of the leaf, leading to heat loss

Homeostasis in plants, IGCSE & GCSE Biology revision notes
Plants maintain an optimum temperature through transpiration

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