Module 5- Plant responses Flashcards
what is herbivory?
the consumption of plants by herbivores
how do plants respond to herbivory (chemical)?
alkaloids, pheromones
what are alkaloids?
bitter tasting compound found in plants e.g. coffee+tobacco
poisonous to many insects
how do alkaloids affect animals?
act as drugs affecting the animals metabolism
what is the role of hormones in leaf loss?
what is phototropism?
A plant’s growth response to light
what is positive phototropism and where is it seen and why?
It is growth towards light
seen in shoots to get maximum light for photosynthesis
what is negative phototropism and where is it seen and why?
it is growth away from light
seen in roots to prevent drying out
what is geotropism?
A plant’s growth response to the earths gravitational field
what geotropism do roots display and why?
positive because they grow towards the gravitational attraction to ensure they grow in the ground
what geotropism do stems/shoots display and why?
negative because they grow away the gravitational attraction to ensure they grow to the light
what are pheromones?
A signal to nearby plants of the same species that they are under attack from herbivores, triggering other defences
how do plants respond to herbivory physically?
folding in response to touch and thorns to wear off insects/scare animals
what type of stress factor is herbivory?
biotic
what are some of the commercial uses of plant hormones?
As selective weed killers
As rooting powders
To control ripening
how can plant hormones be used as weed killers?
high auxin concentration can cause such rapid growth that roots get distorted+damaged allowing pathogens to enter the plant or/and die
how can plant hormones be used as root powders?
low doses of auxin can be used to stimulate cuttings to grow new roots
what hormone can be used as a fruit ripener and how?
ethene,, fruit is harvested unripe so it can be transported without damage then ripened artificially when needed to sell
what does hormone gibberellin do?
cause stem elongation and seed germination
what does hormone ABA/abscisic acid do?
stimulates stomatal opening/closure
what does hormone auxin/IAA do?
-maintains apical dominance
-stimulates stem growth by causing cell elongation
what does hormone ethene do?
stimulates the breakdown of cell walls in abscission layer, causing the leaf to drop off
where is the abscission layer?
base of the leaf stalk
what is apical dominance?
auxins produced at the growing tip at the apex (i.e. the top) of a plant stem causing the stem to grow upwards and also stop lateral (side) buds from growing
what is the endosperm?
a starch-containing energy store surrounding the embryo
what is the aleurone layer?
a protein-rich layer on the outer edge of the endosperm
