Edexcel IGCSE Biology: Double Science 复习笔记 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

   

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 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

Plants maintain an optimum temperature through transpiration

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