Download Plant defence responses

Plant Structure, Disease &
Defence
Use the internet to research plant
defence mechanism – how do they
stop herbivores from eating them or
microorganisms from invading their
cells?
Design a SUPER
PLANT which has
all of the
mechanisms you
research
University of Cambridge
Video
Mechanical adaptations.
• Thorns and hairs deter animals from eating or touching them.
• Leaves which droop or curl when touched.
• Gympie Gympie Tree
“Stung horses that have been known to die
within hours, even jumping off cliffs to
escape their suffering. One man was
purported to have shot himself to end his
pain after having foolishly used the leaf as
toilet paper. ”
Mechanical adaptations.
• Mimicry to trick animals into not eating them or not laying eggs on
the leaves.
Some plants, e.g. this passion
flower mimic the presence of insect eggs
on their leaves, dissuading other species
from laying their eggs there. Female
butterflies are less likely to lay their eggs on
plants that already have butterfly eggs.
Chemical plant defence responses.
• Produce antibacterial chemicals, such as mint and witch hazel.
• Produce poisons to deter herbivores, such as tobacco plants,
foxgloves and deadly nightshade.
Physical defence responses to resist invasion of microorganisms.
• Cellulose cell walls.
• Tough waxy cuticle on leaves.
• Layers of dead cells around stems (bark on trees) which fall off taking
pathogens with them.
.