3.2-plant disease

• How do aphids damage plants?

  They extract sap from the phloem
• What role do aphids play as vectors?

  They transfer pathogens between plants
• Why do plants need nitrate ions?

  To convert sugars into proteins
• What happens if plants lack adequate nitrate supply?

  Growth of the plant will be stunted
• What are the methods to reduce aphid populations?

  • Chemical pesticides
  • Biological pest control using ladybirds
• What are symptoms of disease in plants?

  Stunted growth, spotted leaves, decay
• What does stunted growth indicate in plants?

  Lack of nitrate ions
• What is a symptom of rose black spot fungus?

  Spotted leaves
• What does chlorosis in leaves indicate?

  Insufficient magnesium ions
• Why do plants need magnesium ions?

  To synthesize chlorophyll for photosynthesis
• How can plant diseases be identified?

  • Reference to gardening websites/manuals
  • Laboratory testing
  • Monoclonal antibody test kits
• What are examples of physical defence responses in plants?

  • Cellulose cell walls
  • Tough waxy cuticle on leaves
  • Outside layer on stems/bark
  • Leaf fall
• What are examples of mechanical defence responses in plants?

  • Thorns and hairs to deter animals
  • Leaves that droop/curl on contact
  • Mimicry to trick animals
• What are examples of chemical defence responses in plants?

  • Antibacterial chemicals
  • Poisons