Topics 06-08 Terms (Plant Chunk) Flashcards
endodermal barrier
In roots, casparian strips block flow to the inside where xylem is located
Water/ions must enter endodermal cells to get to xylem
_____% of water taken up from roots lost to _______, mainly in the form of ____
90% of water is lost to evaporation, usually as water vapor
How turgor is maintained
Potassium ion uptake with ATP-powered ion channels
Water enters due to osmotic imbalance
Guard cells control stomata which control turgor
aerenchyma
loose parenchyma with
air spaces
allow oxygen transport to below-water parts
found in water lilies and others
flooding cons
depletes oxygen in roots
loss of active pumping at root hairs
loss of ion entry
may dry out leaves
lenticels
above water; allow oxygen to enter
pneumatophores
spongy, air-filled “knees”
from roots, emerging from
water
Food transport in phloem is mostly ___% dry matter and almost consisting entirely of _____
10-25% dry matter, mostly sucrose
How food transport happens
pressure flow hypothesis
source (place of dissolved carb production)
sink (place of usage
(primarily growing areas –
root and stem tips, fruits)
or storage)
Phloem loading
Carbs enter sieve tubes at source (active transport)
Companion cells provide energy
Water potential in sieve tube lowered, relative to nearby xylem
Increased turgor pressure in sieve tube pushes solution through them
“unloading” at a sink
Carbs leaving drop turgor pressure
Makes the flow from high water pressure at source to low pressure at sink
Most water in sink diffuse back into xylem
Macronutrients in plants
(7) COHNK CaMg (conk, camgie)
Micronutrients in plants
(8) Cl Fe Mn B Zn Cu Ni Mo (“cliffy men, beezin’ sunny mo!”)
How nitrogen is fixed for plants
Nitrogen-fixing bacteria turn N2 into NH3 (ammonia).
Ammonifying bacteria turn NH3 into NH4+.
Nitrifying bacteria turn NH4+ into NO3-.
Plants can only use nitrogen in the form of NH4+ or NO3-
Denitrifying bacteria take ions and turn it back into atmospheric N2
Commercial fertilizers usually include _, _, and _.
N P K
Disadvantages of commercial fertilizers
can be expensive
can pollute water supplies and
damage ecosystems
Organic fertilizer makes ______
Humus; helps hold
water and is usually less polluting of surface waters
Environments of carnivorous plants
sandy, acidic soils (like bogs) often have too
little nitrogen
Venus fly trap
brushed hair causes
electrical impulse, which causes very rapid water accumulation in the outer regions of lobes
digestive enzymes
usually eat more ants/grasshopper than flies
sundews
Trichomes act as glands, secreting sticky substances including digestive enzymes
Leaves curl around prey
butterworts
Glands on leaves secrete sticky
substances and
digestive enzymes
Leaves curl around prey, mostly gnats
pitcher plants
Insects can’t climb back out
Some have digestive enzymes, some digest using other organisms through mutualism
Bladderworts
traps in aqueous environments
bladderlike leaves that have a spring-like trapdoor
digestive enzymes
mycorrhizae
90% of vascular plants have relationships between their roots and these certain fungi
important mostly for phosphorous and micronutrients
Plant development characteristics
Cells do not change positions during development
Growing tips and zones (meristems); regeneration capacity
No fixed body size, flexibility and adaptability
Adaptive development influenced by environment
Fungi and animal development
Fungi grow with little specialization, except for reproduction
Animal development is usually complex but relatively inflexible
suspensor
larger cell in the first division of a seed embryo
links embryo to nutrient tissue in seed
root-shoot axis
Near suspensor = future root
Other end = future shoot
mature seed embryo characteristics
Root-shoot axis
Cotyledons growing out of shoot
Plumule; may have a coleoptile (protective sheath)
Where food is stored in a seed
Endosperm or cotyledons
____% of seeds are water
5-20% water
Food reserves in seeds are mostly ________
starch grains in amyloplasts, protein bodies, sometimes fat bodies
First step in seedling growth
roots emerge first (usually)
Plant hormones control _______
gene expression
Auxin
Elongates cells, and is transported away from areas in the light
Usually found in apical meristems or other immature areas
plasticity of cell walls
bending of stems, stem elongation
inhibits leaf abscission
promotes lateral bud dormancy
Cytokinins
Natural ones similar to adenine
Usually produced in root apical meristems and developing fruits
cell differentiation
works with auxin to stimulate cell division
promote lateral buds, inhibit lateral root growth
promote chloroplast development/maintenance
Gibberellins
Activate production of food utilization enzymes
Made in apical parts of stems and roots
shoot elongation, hastened seed germination
Brassinosteroids
Overlapping functions with auxins and gibberellins
Found in pollen, immature seeds, shoots, and leaves
Oligosaccharins
Pathogen defense (possible reproductive development)
Found in cell walls
Ethylene
Promote some defense responses to environmental stress
Formed around lateral buds stimulated by auxin, in pollinated flowers, developing fruits
lows stem and root growth
hastens fruit ripening
increase in respiration in
fruits
allows abscission at fruit peduncles and leaf
petioles
Abscisic acid
Seed dormancy
Affects stomata opening and closing
Made in mature green leaves, fruits, root caps
produces a yellow area when applied to a green area
very rapid effects; not likely to be due to changes in gene expression
salicyclic acid
Plant defense responses against pathogens
apical dominance depends on combined effects of ____, _____, ______
auxin, cytokinins, ethylene
final plant form typically determined by a balance of ______ and ______
auxin and cytokinins
tropism
growth responses to external stimuli (irreversible growth)
phototropism
Stem systems grow toward light (auxin often involved)
gravitropism
Stems grow up, roots grow down
thigmotropism
Response to contact; examples are tendrils, venus flytrap closing
turgor movements
Reversible changes in turgor pressure
Involves active ion import/export, water influx/efflux to relieve osmotic imbalance
Examples are opening/closing stomata, “opening/closing” leaves and flowers
photoperiodism
response to a length of DARK period
long-day plants
Flower only when the day length is over 12-16 hours
short-day plants
AKA “long night” plants
Flower only when day length is shorter than 14 hours
Color light most effective in stopping flowering
Red light
phytochrome
A blue pigment with two states (Pr and Pfr) involved in flowering
Affects etiolation
Pfr is biologically active, Pr is not
Pfr becomes Pr over time in the dark
