plant responses Flashcards
auxin stimulates…
newly formed cells to get longer
where is auxin produced?
the ends of shoots where it can diffuse down the stem
auxin causes…
phototropism
phototropism
young stems bend towards light
____ inhibits auxin transport
light
auxin elongates cells on___ side
dark
phototropism bends stem toward…
light
how is phototropism used to kill weeds?
makes weeds grow too much unitil they die
cytokinin encourages
cell division
where is cytokinin produced?
in the roots
cytokinin stimulates
branch formation
primary apical meristem inhibits..
branch formation
auxin suppresses ______ from…
auxiliary buds from forming branches
tip of tree produces auxin which is why…
the top of trees have much smaller branches than the bottom of the tree.
cytokinin stimulates…
axillary buds to form branches
___ of tree produces cytokinin
bottom
levels of ___ and ___ determine branch growth
auxin and cytokinin
gibberellin stimulates
cell division and cell elongation
what especially helps fruit grow bigger?
gibberellin
gibberellin is released by
embryo to stimulate germination
abscisic acid prevents …
seed from germinating
what prevents seed from sprouting in the fruit?
abscisic acid
ethylene gas helps sprouts
avoid obstacles
ethylene gas: triple response
o Grows slower
o Becomes thicker and stronger
o Grows horizontally
leaf abscission
dropping leaves (like in the fall)
______ helps fruit ripen
ethylene gas
how do plants detect light?
with phytochrome pigments
red: activates them
darkness: inactivates them
plants open stomata during…
day and close them at night
short day plants flower in the
fall
short day plants flower when nights…
become LONG enough
short day plants seeds overwinter in the soil and ..
sprout the next spring
land day plants flower in the
spring
long day plants flower when night becomes
short enough
long day plants seeds may
sprout immediately or over winter
positive tropism
plant grows toward stimulus
negative tropism
plant grows away from stimulus
common tropisms include
Phototropism, Gravitropism, Thigmotropism
phototropism: shoots have positive phototropism
grows toward light source enabled by auxin which is inhibited by light
phototropism: roots have negative phototropism
grow away form light source
gravitropism: shoots have negative gravitropism
shoots grow away from gravity
gravitropism: roots have positive gravitropism
roots grow toward gravity
negative thigmotropism
most plants grow away from touch
positive thigmotropism
they hold on to larger plants for support
example of positive thigmotropism
vines: reach tendril stems toward touching object
