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GCSE
Biology paper 1
Plant diseases and defences
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Cards (12)
What happens if there aren’t enough mineral ions in the soil
Plants
suffer
deficiency
symptoms
why do plants need nitrates
to make
protines
what happens if plants don’t have enough nitrates
proteins
are needed for growth so a lack of
nitrates
causes stunted growth
what do plants need magnesium ions for
making
chlorophyll
what happens if plants don’t have enough magnesium ions
they have
chlorosis
(yellow leaves) and can’t
photosynthesise
as well
what are aphids
an
insect
that infests and
damages
plants
what are common signs of a plant disease
-stunted
growth
-abnormal
growth
-spots
on the leaves
-malformed
stems or leaves
-patches of
decay
-discolouration
how can plant diseases be identified
-looking up signs in a gardening manual or website
-taking the plant to a
laboratory
-using testing kits that identify the
pathogen
with
monoclonal antibodies
what are physical defences
-waxy
cuticle
which provides a
barrier
to stop pathogens entering
-plant cells have
cell walls
which form another
physical barrier
-layers of
dead cells
around the stems that acts as a
barrier
what are chemical defences
-some plants produce
antibacterial
chemicals to kill bacterial e.g.mint and witch hazel
-other plants produce
poisons
to stop herbivores eating them
what are mechanical defences
-thorns
and
hairs
to stop animals touching/eating them
What are other mechanical defences
Leaves
droop
or
curl
when something ouches them ,they can knock
insects
off and move
away
from things
some plants
mimic
other organisms