Plant Diseases and Defences

• Apart from water, what else do plants absorb from soil?

  Mineral ions
• What are nitrate ions used for in plants?

  • Making proteins
  • Growth
• What does a lack of nitrates cause in plants?

  Stunted growth
• What are magnesium ions used for in plants?

  Making chlorophyll
• What happens to a plant with a magnesium ion deficiency?

  They suffer from chlorosis and their leaves turn yellow
• What pathogens can affect plants?

  Viruses, bacteria and fungi
• Apart from pathogens, what other organism damages plants?

  Insects
• Give one example of an insect which can damage plants

  Aphids
• What are the signs of disease in plants?

  • Stunted growth
  • Spots on leaves
  • Patches of decay
  • Abnormal growths
  • Malformed stems and leaves
  • Discolouration
• How can you identify plants diseases?

  • Using a gardening manual or website
  • Taking it to a laboratory
  • Using testing kits which contain monoclonal antibodies
• What are the physical defences of plants?

  • The waxy cuticle
  • Cell walls made from cellulose
  • Layers of dead cells around stems e.g. tree bark
• What are the chemical defences of plants?

  • Some produce antibacterial chemicals
  • Some produce poisons which deter herbivores
• What are the mechanical defences of plants?

  • Thorns and hairs to stop animals eating and touching
  • Leaves which droop or curl on contact to knock off insects and move away from things
  • Appearances which mimic other organisms
• Give 2 examples of plants which produce antibacterial chemicals

  • Witch hazel
  • Mint plants
• Give 3 examples of plants which produce poisons

  • Tobacco plants
  • Foxgloves
  • Deadly nightshade
• Give 2 examples of plants which use their appearance to deter organisms and explain how

  • The passion flower has yellow spots to mimic butterfly eggs so butterflies wont lay them on their leaves
  • Plants in the 'ice plant family' look like stones and pebbles to prevent being eaten