Edexcel IGCSE Biology 复习笔记 1.1.5 Living Organisms: Movement & Control

Edexcel IGCSE Biology 复习笔记 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

 

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

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

 

Plants maintain an optimum temperature through transpiration

转载自savemyexam

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