Chapter Eleven: Growth and Development Flashcards
plant growth and development is regulated by ____
hormones
what are the 5 plant hormones
- auxins
- gibberellins
- cytokinins
- ethylene
- abscisic acid (ABA)
plants do not have a(n) ___ or ___ system
endocrine or nervous
a chemical substance produced in one place that stimulates something somewhere else
hormone
a hormone that impacts the cell it is produced in
autocrine
plants interact with their environment through their ____
growth
meristematic tissues are regulated by ____
hormones
our overall understanding of plant hormones is ____, especially compared to our understanding of animal hormones
premature
the first hormone discovered in plants
auxin
auxins promote ___, ___, ___, and ___
cell division, elongation, maturation, and genetic competence
auxins are involved in every _____
growth phenomenon (promotion and inhibition)
auxins promote ____, meaning that the plants are generally dominant at the tip
apical dominance
auxins are synthesized in ___, ___, and ___
shoot tips, young leaves, and seed embryos
4 major actions of auxins
- promotes cell elongation
- inhibits growth of lateral buds
- inhibits lead and fruit abscission
- stimulates synthesis of ethylene
growth toward a light source
phototropism
most active naturally occurring auxin
IAA
two commercial uses of IAA
- stimulates root growth in cuttings
- stimulates some plants to produce fruit without being fertilized
agent orange; used in Vietnam war to kill broadleaf plants; harmful to soldiers
2,4,5-T
gibberellins are synthesized in ___ and ___
young shoots and developing seeds
3 major actions of gibberellins
- promotes elongation of cells
- stimulates flowering and fruit development
- stimulates seed germination
2 commercial uses of gibberellins
- elongates flower stems of cyclamen plants
- lengthens stems of grapes and increases fruit size
a ____ amount go gibberellins is needed to produce a large response
small
cytokinins are synthesized in ___, ___, and ___
roots, embryos, and fruits
3 major actions of cytokinins
- stimulates cytokinesis
- stimulates growth of lateral buds
- delays leaf senescence
effects of cytokinins are influenced by _____
auxin concentration
if the apical meristem is intact or close by, auxin in that meristem will ______
suppress lateral growth (apical dominance)
3 commercial uses of cytokinins
- extends shelf life of leafy vegetables
- keeps cut flowers fresh
- promotes branching in Christmas trees
ethylene is only ___ hormone, unlike the others which are a ____
one
group
ethylene is growth ____
inhibiting
ethylene is the only plant hormone that is a ____
gas
ethylene is synthesized in ____
all plants parts
3 major actions of ethylene
- promotes fruit ripening
- stimulates leaf and flower senescence
- stimulates leaf and fruit abscission
commercial use of ethylene
ripe climacteric fruits that are picked green
fruits that enter a ripening phase
climacteric fruits
once climacteric fruits enter the ripening phase, they will ______
ripen on or off the vine
non-climacteric fruits do not respond to ____
ethylene
the stress hormone
abscisic acid (ABA)
ABA helps plants cope with _____
adverse conditions
abscisic acid is synthesized in ___ and ___
mature leaves and plants under stress
3 major actions of abscisic acid (ABA)
- inhibits growth
- closes stomata
- induces and maintains seed dormancy
one commercial use for ABA
inhibits growth of plants that are able to be shipped for manufacture
plants move with ___ and ___
precision and intention
plant growth directed toward or away from an environmental stimulus
tropic movement
growth in response to unidirectional light
phototropism
____ are primarily phototrophic
plant shoots
bending of plant shoots results from ____ on shaded side of plant
auxin accumulation
growth in response to gravity
gravitropism
___ are primarily gravitropic
roots
___ and ___ are negatively gravitropic
shoots and stems
____ in root cells function as statoliths (gravity detectors)
amyloplasts
a shift in the statolith signals in amyloplasts causes a ____
redistribution of auxin
growth in response to touch
thigmotropism
passion vine tendrils exhibit ____ thigmotropism
positive
plant movements that are not oriented with respect to a stimulus
mastic movements
a mastic response to touch
thigmonasty
example of thigmonasty
leaflet folding of “sensitive plant”
how does thigmonasty in the sensitive plant work
rapid movement of water internally
mastic response to the daily rhythms of light and dark
nyctinasty
nyctinasty is also referred to as ____
sleep movement
____ is the main trigger for responses to seasonal changes
light
___ and ___ also have influences on plant responses to seasonal changes
temperature and water availability
4 plant processes that occur at specific times of the year
- flowering
- seed germination
- senescence
- dormancy
grey/blueish pigment found in all plants
phytochrome
phytochrome is sensitive to ___ and ___
red light and infrared light
two forms of phytochrome
- PR (phytochrome red)
- PFR (phytochrome far red)
___ is the active form of phytochrome
phytochrome far red PFR
red wavelengths are used by plants to measure ____
day length (really night length)
the number of hours of light in a 24 hour day
photoperiod
when phytochrome is exposed to red wavelengths, it chemically changes to the ____ form
PFR (active)
when red wavelengths diminish, phytochrome chemically changes to the ____ form
PR (inactive)
4 categories of flowering plants
- long day
- short day
- day neutral
- intermediate
____ is important for plants to detect to know when to carry out certain processes
uninterrupted darkness
why do plants detect uninterrupted darkness instead of day light?
quality of light can vary from day to day, but darkness it generally the same every night
critical length of light period
12-14 hours
bloom when light periods are longer than critical length
long day plants
long day plants bloom in the ___ and ___
late spring and early summer
bloom when light periods are shorter than critical length
short day plants
short day plants bloom in the ___ and ___
late summer and fall
do not rely on photoperiod to stimulate flowering
day neutral plants
day neutral plants bloom in the ___, ___, and ___ and are typically located in the ____
spring, summer and fall
tropics
if seeds are buried too deep, phytochrome can’t convert to PFR, and _____ will not occur
seed germination
red light ____ germination
far red light ____ germination
stimulates (PR -> PFR)
inhibits (PFR -> PR)
destruction of chlorophyll and production of anthocyanin in autumn
leaf senescence
a period of decreased metabolism in plants
dormancy
leaf senescence and dormancy are impacted by _____
phytochrome
