Plant defences: Infection and response: Biology: GCSE (9:1)

• Physical defences

  Barriers that reduce the invasion of pathogens
• Cellulose cell walls


  Strengthen plant cells to help resist pathogens

  
• Waxy cuticle


  The surface of a leaf which act as a barrier to pathogens

  
• Layers of dead cells

  A protective layer that can fall off a plant and take pathogens with them

  
• Bark

  A protective layer on the trunks of trees which act as a barrier to pathogens

  
• Chemical defences


  Chemicals that protect plants against pathogens
• Antibacterial chemicals


  Chemicals that protect plants against bacterial infections
• Poisons


  Chemicals to deter herbivores from grazing on plants
• Mechanical adaptations

  Physical adaptations such as thorns that prevent damage to plants
• Thorns


  Sharp growths which prevent damage from herbivores

  
• Plant hairs


  Can irritate the mouth of herbivores which makes the plant difficult to eat

  
• Touch-sensitive leaves


  Leaves droop or curl which can dislodge insects or deter large herbivores

  
• Mimicry


  Plants mimic unhealthy or dangerous plants to prevent damage