Plant disease

• How do aphids cause damage to plants?

  Extract sap with mouthparts
• Aphids weaken plants by extracting sap from the phloem
• Aphids can transmit pathogens from diseased to healthy plants.
• What are two ways to reduce the number of aphids?

  Chemical pesticides, biological control
• Biological pest control involves using ladybirds
• Why do plants need nitrate ions?

  Convert sugars into proteins
• A lack of nitrate ions can stunt plant growth.
• Why do plants need magnesium ions?

  Synthesise chlorophyll
• A deficiency in magnesium ions causes leaves to turn yellow
• What are some symptoms of disease in plants?

  Stunted growth, spotted leaves
• Decay and rotting are symptoms of plant disease.
• Match the method of identifying plant disease with its description:

  Gardening manual ↔️ Reference to descriptions in a guide

  Laboratory testing ↔️ Analysis of plant samples

  Monoclonal antibody test kits ↔️ Specific detection of pathogens
• What are three examples of physical defense responses in plants?

  Cellulose walls, waxy cuticle, leaf fall
• Plants use cellulose cell walls as a physical defense.
• A tough waxy cuticle on leaves prevents pathogens from entering the plant.
• What are two examples of chemical defense responses in plants?

  Antibacterial chemicals, poisons
• What are three examples of mechanical defense responses in plants?

  Thorns, drooping leaves, mimicry
• Thorns on plants deter animals from eating them.