PLANT RESPONSES Flashcards
(24 cards)
toxic chemicals released by plants
alkaloids- bitter tasting, bad smell, poisonous
tannins- bitter taste and can bind to proteins in the gut making the plant hard to digest
what are pheromones
alarm pheromones- causes nearby plants to detect these chemicals and start producing chemical defences
corn plants release pheromones when being eaten by caterpillars which attracts parasitic wasps
what do carrots produce at low temps?
antifreeze proteins which bind to ice crystals and lower temperature that water freezes at
what is a tropism
the response of a plant to a directional stimulus
phototropism
plants response to light
geotropism
growth of plant in response to gravity
hydrotropism
plant growth in response to water
thermotropism
plant growth in response to temperature
thigmotropism
plant growth in response to contact with an object
gibberellin
stimulates seed germination
stem elongation
side shoot formation
flowering
auxins
growth of shoots by cell elongation
what stimulates cell elongation
IAA
how does IAA move around the plant
short distance- diffusion and active transport
long distance- phloem
where does IAA move in phototropism and geotropism
phototropism- moves to shaded part of shoots and roots
geotropism- moves to underside of the shoots and roots
apical bud
shoot tip of flowering plant
apical dominance
auxins stimulate the growth of apical buds and inhibits the growth of side shoots from lateral buds
how do side shoots grow when apical bud has been removed
cell division and cell elongation
how do gibberellins stimulate seed germination?
triggering the breakdown of starch into glucose in the seed
the plants embryo can then use the glucose to begin respiring and release the energy it needs to grow
what are gibberellins inhibited by?
abscisic acid
which hormones inhibit leaf loss?
auxins- as leafs gets older the less auxin is produced causing leaf loss
ethene- as leaf gets older, more ethene produced
what does ethene do
develops a layer of cells at the bottom of the leaf stalk
this abscission layer separates the lead from the plant
ethene stimulates the cells in the abscission layer to expand which breaks down the cell walls and causes the leaf to fall off
how does abscisic acid trigger stomatal closure?
binds to receptors on guard cell membranes causing specific channels to open which allows calcium ions to enter the cytosine from the vacuole
increased concentration of calcium ions causes other ion channels to open
ion channels allow ions to leave guard cells which raises the water potential
water leaves guard cells by osmosis
guards cells become flaccid and the stomata close
how is ethene used in the fruit industry?
stimulates enzymes that break down cell walls, it breaks down chlorophyll and converts starch into sugars
makes fruit ripe, soft and ready to eat
how are auxins used by farmers and gardeners?
used in selective weed killers
used in rooting hormones- make plant cuttings grow roots which is quick and cheap
