4.3.3.2 Plant Defence Responses

Question 1

What are physical defence responses of plants used to do?

Answer 1

used to resist invasion of microorganisms

Question 2

What are the physical defence responses of plants?

Answer 2

• cellulose cell walls to form a physical barrier into the cells
• tough waxy cuticle on leaves stops entry into leaves
• layers of dead cells around stems (e.g. bark) which stops pathogens from entering as the dead cells fall off with the pathogens

Question 3

What are chemical defence responses of plants used to do?

Answer 3

used to deter predators or kill bacteria

Question 4

What are the chemical defence responses of plants?

Answer 4

• poisons (e.g. foxgloves, tobacco plants, deadly nightshade, yew etc.) to deter herbivores and stop predators from eating the plant
• antibacterial chemical compounds kill bacteria e.g. mint plant and witch hazel

Question 5

What are the mechanical adaptations of plants to defend themselves?

Answer 5

• thorns and hairs deter animals as it makes it difficult and painful for animals to eat the plant (don’t defend against insects)
• some leaves can droop or curl when touched which allows them to move away and move insects off their leaves
• mimicry to trick animals
  
  • some plants droop to look like unhealthy plants so that animals avoid them
  • plant have patterns that appear to look like butterfly eggs, so butterflies don’t lay their eggs here in order to avoid competition
  • species from the ‘ice plant family’ have a stone and pebble like appearance in order to avoid predation