3.3.2 Plant defence responses

• Give examples of physical defence responses

  1. Cellulose cell wall → tough for microorganisms / pathogens to penetrate

  2. Waxy cuticle on leaves → tough for microorganisms / pathogens to penetrate

  3. Layers of dead cells around stems (tree bark) → fall off, taking microorganisms / pathogens with them
• Give examples of chemical defence responses

  1. Antibacterial chemicals → kill bacterial pathogens
  2. Poisons (eg. berries) → deter herbivores that could eat / damage plants
• ve examples of mechanical adaptations

  1. Thorns / hairs → deter herbivores that could eat / damage plants
  2. Leaves which droop / curl when touched → dislodges insects that might feed on plants / scare animals
  3. Mimicry (copy appearance of others) → trick organisms into not eating / laying eggs on pla
• An example of mimicry

  The passion flower vine has evolved small yellow spots on its leaves that look like butterfly eggs → butterflies don’t lay eggs on leaves → plant avoids damage from feeding caterpillars.
• why is this statement wrong?

  "Thorns / hairs deter predators.”

  A predator is a consumer that kills and eats other animals. Thorns / hairs deter herbivores (who eat plants)
• A deadly nightshade plant has poisonous berries. How will this help the deadly nightshade plant to survive? (1)

  ● Will stop animals / herbivores eating it
• The leaves of some plants release oils onto their surface. Suggest how the production of oil on the surface of a leaf may protect the plant from aphids. (1)

  ● Prevents aphids from attaching to leaf / causes aphids to slide off leaf

  ● OR may harm / kill aphids
• Hornets are insects that sting other animals and cause pain. Hornet moths look similar but do not sting other animals. Suggest how mimicry helps the hornet moth survive. (1)

  ● (It looks like the hornet so) predators / animals are tricked / deceived and so avoid eating it
• The gorse plant has sharp spines. How do these help the gorse plant survive? (1)

  ● Stop the plant being eaten / prevent animals damaging the plant