unit 2: plants Flashcards
services of plants
food, natural products, ecosystem services, culture,
group of plants that produce flowers, more recently evolved, largest group of plants
angiosperms
when did the invasion of land plants begin
475 Ma
challenges to land invasion of plants
maintain water in cells, structure, reproduction
what advantage led to land invasion
less competition for light
ancestor of land plants
green algae (charophyte)
traits of algaeshared with land plants
cellulose cell wall, chlorophyll a and b, sperm with anterior flagella,
traits allowing for land invasion
spores covered in sporopollenin, dispersal by wind, fresh water
charophyte life cycle
diploid zygote undergoes meiosis to create spores, leading to adult algae through mitosis
most stable bipolymer, decay resistant, dehydration resistant, UV protectant
sporopollenin
essential for acquiring nutrients, transformed land surface
mycorrhizal fungi
broke down rocks, died in soil (organic matter)
soil led to rivers which led to nutrients in oceans
arose in 425 Ma, caused rapid adaptation for life on land
vascular plants
slows water loss, inhibits gas exchange, stromata/pores needed
cuticle
major adaptations shared by all land plants
cuticle, pores/stromata, embryo
alternation of generations in life cycle
zygote undergoes mitosis to create sporophyte, then meiosis to spores, then mitosis to gametophyte
young sporophyte nourished by maternal tissue
embryo
liverworts, mosses, and hornworts, gametophyte dominant
bryophyte
what does a dominant gametophyte mean
sporophyte lives on and depends on gametophyte
sporophytes became larger and more complex as
vascular system was acquired
why did sporophyte dominance develop
so plants could grow taller (spore dispersal) and because gametophytes are constrained by water needs
sporophyte and gametophyte are independent
ferns
sporophyte dominant, involves conifers
gymnosperms
rely on soil water, actively control hydration, allow for bigger size, can carry out PS in dry conditions
vascular plants
outer layer of cells, protective
epidermis
major organ types of vascular plants
leaves, reproductive organs, stems (make up shoot) and roots
transports water through low resistance pathway
xylem (vascular tissue)
transports sugars
phloem (vascular tissue)
everything not epidermal or vascular tissue
ground tissue
common ground tissue
parenchyma, performs metabolism
cells lack cytoplasm and membrane, conduits, vessels, pits, angiosperm have higher transport capacity
xylem features
how water is pulled through xylem
evaporative pump
land, embryo, alternation of generations, stromata, cuticle
features of all land plants
long lives sporophyte, vascular system
ferns, gymnosperms, angiosperms
seeds
gymnosperms and angiosperms
flowers
angiosperms
order of trait evolution
alt of gens, stromata, long lives sporophyte, vascular system, seeds, flowers
ecologically dominate, ovules and seeds enclosed in sporophyll, double fertilization
angiosperms
major innovation allowing sporophyte dominance
seed,
female gametophyte of angiosperms
stays on sporophyte
male gametophyte of angiosperms
becomes pollen grain
delivers male gametophyte (sperm) to female gametophyte
pollination
embryo and food supply
seed
where is pollen delivered to
ovule
angiosperm pollen delivery
pollen goes into carpel tissue (ovule encased in sporo carpel)
why are seeds better than spores
seed remain dormant until environment is favorable, seeds have food supply, seeds can be transported by animals
do seed plants make spores
yes, but they are not dispersed, become gametophytes
fertilized ovule
seed
structure derived from ovary, encloses seed
flower
ovary, style, and stigma
pistil (female)
female gametophyte make up
7 cells, 8 nuclei
where male gameophyte is made
anther and filament (stamen)
sporophyll with pollen sacs containing pollen
stamen
male gametophyte make up
3 cells, creates 4 spores and 4 gametophytes each
path of pollen
stigma, style, ovules
triploid cell created in double fertilization
endosperm
spore undergoes what process to become gametophyte
mitosis
ovule undergoes what to become seed
fertilization
ovary and carpel tissue undergo what to become fruit
fertilization
what happens when pollen touches appropriate stigma
travels pollen tube
grow down style, find egg cell
pollen tubes
unique to angiosperm
double fertilization
pollen tube delivers one sperm to egg creating
zygote and embryo
other sperm delivered to two polar nuclei creating
endosperm
nutritive tissue that feeds embryo
endosperm
contains 2 cotyledons
eudicots
contains 1 cotyledon
monocot
contain meristem tissue, involved in primary growth
apical and axillary bud
elongates shoots and roots, produces leaves and reproductive structures
primary growth
is plant growth indeterminate (stops at a size)
no
determined by location
plant cell function
do zones stay with the tip?
yes
zones from top to end of tip
zone of differentiation, zone of elongation, zone of cell division
uptakes water and nutrients
roots
what type of tissue does primary growth form
vascular, ground, dermal
examples of dermal tissue
epidermis, guard cells, lower epidermis
examples of ground tissue
mesophyll, bundle sheath cell, pith, cortex
examples of vascular tissue
vascular bundle, xylem, phloem, vein,
does secondary growth occur in monocots
no
what happens in secondary growth
a secondary xylem and phloem forms, a cork cambium forms to create bark,
positive tropism
towards stimuli
negative stimuli
away from stimuli
heliotropism
light stimuli, grows toward
thigmotropism
touch stimuli
signal transduction pathway of tropisms
reception, relay proteins and secondary messengers, activation of responses
cells on shaded side elongate faster, curves toward light
phototropism
protein that is stimulated by blue light, leading to signals for phototropism
phototropin
shade results in
differential activation of phototropin
indoleactic acid, transmits signals, constantly made while tip growing, when light from side, differential activation
auxin
auxin binds to receptor that stimulates membrane bound proton pump, cell wall becomes more acidic, low pH activates expansins, separates polysaccharides, expansin increases cell wall extensability, osmosis draws water into cell, cell expands
acid growth hypothesis
rings in trunk correlate with
tree age
senses light in tip of plant
phototropin
if no auxin present
no cell expansion (division but not elongation)
process instigated by changes in hormone concentration, response to changes in light and temperature
leaf abscission
chlorophyll production stops, nutrients and sugars moved to stem and roots for storage, cells divide but don’t expand
leaf abscission
present in green leaves
chlorophyll
present in yellow leaves
xanthaphylls
present in orange leaves
carotenes
aid in light absorption during photosynthesis
carotenoids
are colors of yellow and orange always the same
yes
present in red leaves
anthrocyanins
conditions that favor photosynthesis
increase brilliance of red
only tannins left in leaves
brown leaves
cells divide but don’t expand, cells walls broken down, cells begin to separate,
leaf abscission
primary purpose is absorption of light and CO2 for PS
leaves
reasons leaves are thin
diffusion difference shorter for CO2, more light absorbed,
60 percent of mesophyll, little air volume, lots of chloroplasts
palisade mesophyll
40 percent of mesophyll, lots of air volume, fewer chloroplasts
spongy mesophyll
which type of mesophyll is used more for photosynthesis
palisade
why is spongy mesophyll present
diffuses CO2 faster
why did the structure of leaves evolve
to maximize absorption of light in the wavelengths that drive PS
allows leaves to regulate water loss and carbon gain
stromata
restricts water loss from leaves but inhibits CO2 uptake
cuticle
light reflecting back into palisade mesophyll from spongy
backscatter
the greater number of air water interfaces in spongy mesophyll allows for more
light absorption in palisade chloroplasts
what adds most of plant mass
CO2
where do light reactions and the calvin cycle occur
chloroplast
what does the calvin cycle produce
NADP, ADP, and sugars
what do light reactions produce
ATP, NADPH, and oxygen
what is needed for a light reaction
light and water
occurs in stroma, creates sugars
calvin cycle
what fixes inorganic CO2 into a biochemical molecule
rubisco
what reactions use rubisco
calvin cycle and photorespiration, fix carbon and oxygen respectively
why is photorespiration not efficient
fixes oxygen, decreases amount of sugar made per light absorbed, happens under stress
why does rubsico fix oxygen
evolved a ta time of high CO2
separates light reactions and calvin cycle, mesophyll (PEP C) and bundle sheath (rubisco), good for high light, dry env
C4 photosynthesis
steps of C4 PS
PEP C fixes CO2 in mesophyll, organic acid moved to bundle sheath, rubsico fixes CO2, calvin cycle
what does C4 PS eliminate
photorespiration
C4 benefits
high PS capacity, high yield, high water use efficiency
C4 drawbacks
CO2 pump costs lots of ATP
do all plants do C3 PS
YES
separated temporally, similar to C4
CAM PS
CO2 stored at night, occurs in one cell, eliminates photorespiration, good for dry, hot environments
CAM PS
3 common types of CAM plants
desert, epiphyte, aquatic
in CAM, when doe rubisco work
day
do all plants have bundle sheath cells
yes
how does CAM take CO2 at night
PEP C
what does water hydrogen bonding allow
universal solvent, cohesive, adhesive
method of water transport, high to low conc, occurs due to random molecule movement, no membrane necessary
diffusion
method of water transport, driven by pressure gradient, transport over large distances
mass flow
specialized diffusion over selectively permeable membrane, water potential determines direction of movement
osmosis
equation for water potential
potential = pressure potential + solute potential
water moves from high potential to
low potential
solute potential becomes more negative as
solutes become more concentrated
what is the equilibrium water potential of two small cells
the average of both water potentials
why do plants need water
photosynthesis, expand and grow cells, transpiration
what is the WP of a small cell at equilibrium in a big beaker
the WP of the beakers
evaporation of water out of stomata, provides transport of nutrients from roots to leaves, cools leaves, allows stomata to stay open for CO2 absorption
transpiration
what percent of water is used for transpiration
95 percent
drives flow of water out of leaf
vapor pressure difference
pressure exerted by a vapor on a liquid
vapor pressure
low humidity means
low vapor pressure
partial pressure of water vapor over saturated (possible) vapor pressure
relative humidity
where is vapor pressure always higher
inside the leaf, evaporates out
VP inside leaf - VP outside leaf
VPD
lower relative humidity will
increase VPD
stomatal conductance
how many and how open stomata are
what determines how open stomata are
guard cells
steps of guard cells opening stomata
make ATP in chloroplasts through PS, use to pump protons out, ions taken up creating gradient, solutes accumulate, decreasing WP, osmotic water uptake, cell swells opening stomata
is stomata opening energy dependent
yes
increasing CO2 concentration means
stomata close (low conc is when open and lots of PS)
increasing VPD means
stomata close (dry air)
increased leaf temp means
stomata open until too hot
increased light means
stomata open
dryer soil means
stomata closed
how much water is needed for transpiration
a LOT
increased plant size means
increased water needed
what cells move water
xylem cells (trachids and vessels in conduits)
tracheids and vessels of xylem
are dead when functioning, have 2 cell walls, elongated
how is water moved from roots to leaves
pulled along a gradient in negative pressure potential
water within a plant is
in a continuous network
how is water held up
surface tension of tiny menisci that form in microfibrils and adhere water to cellulose, forms water columns from xylem to evaporation site
what forms a negative pressure at the site of evaporation
a pointy meniscus, means stomata open
where does water travel to
site of evaporation through mass flow driven by the negative gradient
cohesion tension theory
drop in pressure potential creates a gradient in the plant, potential is highest near soil, lowest at top of plant
how is cohesion involved
cohesion keeps water columns intact
highest to lowest pressure potential of plant
soil, root, stem, leaf, atmosphere
why do plants need phloem
to move sugars from leaves to other parts
what does the phloem move
low weight sugars, oligosaccharides (photosynthates)
why are low weight sugars good
strong impact on solute potential, soluble in water, stable
examples of sources for phloem sugars
leaves, PS stems, storage in cells and roots
examples of phloem sinks
roots, developing leaves, reproductive structures, stems, meristems
parts of phloem
sieve tubes and ccells
sieve tubes and cells
are alive, have cell membrane, thick walls, elongated, very modified cytoplasm (no nucleus)
