Plant Defences

• What are the different types of defences that plants have

  • Physical defences/responses
  • Chemical defences/responses 
  • Mechanical defences/responses
• What are the different types of physical defences in plants

  • Cellulose cell wall - this is difficult for microorganisms such as bacteria to penetrate , which protects the plant from attack
  • Tough waxy cuticle on leaves - this is difficult for microorganisms such as bacteria to penetrate , which protects the plant from attack
  • Layers of dead cells around stems , like bark on trees - these dead cells are a barrier to pathogens trying to enter the plant , and as they age , they fall off and take pathogens with them
• What are the different types of chemical defences in plants

  • Antibacterial chemicals are released by plants , and they kill bacteria to prevent them entering the plant (They are made by plants such as mint and witch hazel) 
  • Poisons are released by plants, and they deter herbivores from grazing on the plant (They are made by plants such as tobacco , foxgloves and deadly nightshade)t
• What are the different types of chemical defences in plants

  • Antibacterial chemicals are released by plants , and they kill bacteria to prevent them entering the plant (They are made by plants such as mint and witch hazel) 
  • Poisons are released by plants, and they deter herbivores from grazing on the plan (They are made by plants such as tobacco , foxgloves and deadly nightshade)t
• What are the different types of mechanical defences in plants?

  • Thorns directly protect plants by deterring herbivores from eating/touching them  
  • Hairs irritate the mouth of herbivores making the plant difficult to eat
  • Leaves droop or curl when touched - this might scare herbivores which are not used to this plant (e.g. mimosa leaves)
  • Mimicry is used to trick animals into not eating or laying on plants (E.g. white deadnettle does not sting , but it looks similar to stinging nettle - Herbivores are less likely to eat white deadnettle in order to not mistake it for stinging nettle)