Edexcel IGCSE Biology

Revision Notes

1.1.5 Living Organisms: Movement & Control

Movement

  • 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

Control

  • 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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Ruth graduated from Sheffield University with a degree in Biology and went on to teach Science in London whilst also completing an MA in innovation in Education. With 10 years of teaching experience across the 3 key science disciplines, Ruth decided to set up a tutoring business to support students in her local area. Ruth has worked with several exam boards and loves to use her experience to produce educational materials which make the mark schemes accessible to all students.
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