Plant defence responses

• What types of threats do plants face?

  Pathogens, herbivores, and environmental stressors
• What are the three types of plant defence responses?

  • Physical defences
  • Chemical defences
  • Mechanical defences
• What is the function of physical defences in plants?

  Prevent pathogens from entering the plant
• What is a waxy cuticle?

  A thick, waterproof layer on leaves and stems
• How does the waxy cuticle help prevent pathogen entry?

  It prevents water accumulation needed for pathogens
• What are cell walls made of?

  Cellulose
• What additional material can strengthen cell walls?

  Lignin
• What role do cell walls play in plant defence?

  Provide structural support and second line of defence
• How do layers of dead cells, like bark, contribute to plant defence?

  They act as a tough protective barrier
• What happens when bark sheds?

  It removes pathogens on the surface
• What do plants produce as part of their chemical defences?

  Antimicrobial substances
• What is the function of antibacterial chemicals in plants?

  To kill bacteria and reduce infections
• Which plants are known for producing antibacterial substances?

  Mint and witch hazel
• What do antifungal chemicals do in plants?

  Prevent fungal growth
• Which plant produces antifungal compounds?

  Chrysanthemums
• How do toxins deter herbivores?

  They make plants taste bitter or poisonous
• What toxin do foxgloves produce?

  Digitalis
• What effect does digitalis have?

  Affects the heart
• What toxin do tobacco plants produce?

  Nicotine
• What is the role of thorns and spines in plants?

  To discourage herbivores from feeding
• Which plants have thorns?

  Roses and blackberries
• How do cacti deter animals?

  With sharp spines instead of leaves
• What happens to leaves of some plants when touched?

  They rapidly fold, deterring insects
• How does mimicry help plants survive?

  By looking like dangerous plants to deter herbivores
• What does the passion flower mimic?

  Butterfly eggs
• What are the three main types of plant defence responses?

  Physical, chemical, and mechanical
• What is the function of the waxy cuticle on plant leaves and stems?

  Prevents water accumulation and pathogen entry
• How do the cell walls of plants act as a defence mechanism?

  They provide a second line of defence against pathogens
• What is the function of the layers of dead cells (e.g. bark) on the outer surface of plants?

  Acts as a tough protective barrier against pathogens
• How do the drooping or curling leaves of some plants act as a mechanical defence?

  They make it harder for insects to land or eat the leaves
• Why are plant defences important?

  They protect plants from diseases and herbivores, reducing crop damage and increasing food security
• What are the strengths and weaknesses of the different types of plant defence mechanisms?

  Strengths:

  • Physical defences act as physical barriers to prevent pathogen entry
  • Chemical defences can kill pathogens or deter herbivores
  • Mechanical defences physically discourage herbivores

  
  

  Weaknesses:

  • Physical defences can be overcome by some pathogens
  • Chemical defences can be metabolized or avoided by some herbivores
  • Mechanical defences may not be effective against all herbivores
• If a plant has a thick, waxy cuticle on its leaves, how would this help protect the plant from pathogens?

  The waxy cuticle prevents water accumulation, reducing the likelihood of pathogen entry
• If a plant has lignin in its cell walls, how would this help protect the plant from pathogens?

  The lignin strengthens the cell walls, making them more resistant to pathogens
• How do the physical, chemical, and mechanical defences of plants work together to provide comprehensive protection?

  The physical defences act as barriers, the chemical defences kill or deter threats, and the mechanical defences physically discourage herbivores
• If a plant has thorns on its stems, how would this help protect the plant from herbivores?

  The thorns physically discourage herbivores from feeding on the plant
• If a plant rapidly folds its leaves when touched, how would this help protect the plant from herbivores and insects?

  The folding leaves make it harder for insects to land on or eat the plant
• How do plants that mimic other dangerous plants or objects benefit from this adaptation?

  Mimicry deters herbivores from eating the plant, as they mistake it for a more dangerous species
• How do the different types of plant defence mechanisms work together to protect the plant?

  • Physical defences act as initial barriers to prevent pathogen entry
  • Chemical defences kill or deter pathogens and herbivores
  • Mechanical defences physically discourage herbivores from feeding on the plant

  The combination of these defence mechanisms provides comprehensive protection for the plant.
• What are the key differences between the function and operation of scanning electron microscopes (SEMs) and transmission electron microscopes (TEMs)?

  • SEMs produce 3D images, while TEMs produce 2D images
  • SEMs scan the surface of a sample, while TEMs transmit electrons through a thin sample
  • SEMs are better for studying surface features, while TEMs are better for internal cellular structures