Plant disease

• How do aphids cause damage to plants

  They use their sharp mouthparts to extract sap from the plant phloem weakening the pnag they are also vectors who can transfer pathogens from diseased plants to healthy plants
• How can we reduce the number of aphids

  • Chemical pesticides
  • biological pest control- using ladybirds
• Why do plants need a good supply of nitrate ions

  Nitrate ions are required to convert sugars into proteins which are required for the plant to grow. As a result the growth of the plant will be stunted if there is not an adequate supply of nitrates
• Why do plants need a good supply of magnesium ions

  Magnesium ions are required to synthesise chlorophyll which absorbs light energy during photosynthesis.as a result the leaves cannot photosynthesise properly and they turn yellow (chlorosis)
• What are the symptoms of a disease in plants

  • Stunted growth
  • spotted leaves
  • decay/rotting
  • growths
  • malformation of stems/leaves
  • discolouration
  • presence of pests
• What are three ways in which plant disease can be identified

  • Reference to a gardening website or manual
  • laboratory testing
  • monoclonal antibody test kits
• Give examples of physical defence responses used by plants

  • Cellulose cell walls
  • tough waxy cuticle on leaves
  • outside layer on stems/bark on trees
  • leaf fall
• Give examples of chemical defence responses used by plants

  • Antibacterial chemicals
  • poisons
• Give an example of mechanical defence responses used by plants

  • Thorns and hairs to deter animals
  • leaves that droop/curl on contact
  • mimicry to trick animals