Glossary of plants2

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Leaf structure
function always follows structure
primary function of leaves is photosynthesis
have broad/flat surface to capture sunlight
Pinnately compound
one large leaf where blade is broken down into leaflets
Palmately compound
all leaflets are attached at a certain point
How can we tell the difference?
by the presence of axillary buds; all leaflets in compound leaves are in the same plane
non cellular layer of wax - used to minimize water loss
Use wax to minimize water loss because it is a hydrocarbon
composed of hydrogen and carbon - have same electronegativit and thereofre all bonds are nonpolar
But water is polar so can't pass through
Palasade mesophyll
elongated cells, where most of chloroplasts are found - where photosynthesis takes place
xylem on top and phloem on bottom - way it is arranged in the stem
Also have parenchyma and sclerenchyma
Most of the time do NOT contain chloroplasts
Spongy mesophyll
also have chloroplasts - not as much (bc it is farther away from the surface)
Why is mesophyll widely spaced?
plant requires CO2 - can diffuse around these cells
Bundle sheath function
regulates water and sugar into and out of veins
function is to allow CO2 to diffuse into the leaf
How to tell high plant from low plant?
by layers of palasade mesophyll - more layers in high plant
plants which grow in intermediate moisture (lilac)
Have collenchyma instead of sclerenchyma to allow for flexibilty
thicked PCW at edges of cells - provides flexible support - has pectin rather than lignin
Why do smaller leaves have lower temperatures than large leaves?
smaller leaves have larger SA to volume ratio, so can get rid of heat easier - air is also a factor: able to conduct heat away from leaves
Epidermal cells shape:
not rectangular - have interdigitated shape - which allows it to be stronger
plants that grow in very dry conditions
desert plants - only out cell wall on outside to minimize water loss
Trichomes Functions
Protection - against insects
Increases reflectance
Reduces transpiration
Secrete compounds onto leaf surface
Insulation - reduces heat loss
Increased reflectance
when too much light is absorbed it will overheat
Reduces transpiration
increases boundary layer which slows water loss
Keeping stilla ir near leaf reduces heat loss
Lamb's ear
has dense covering for defence, increased reflectance, slows transpiration
Hydrophytes have
very large air spaces
stomata only on upper surface
large, star shaped, thick cell walls - defence
air spaces
for storage of oxygen (aerenchyma tissue)
Xerophytes have
thick cuticle
stomatal crypt
multiple layers of epidermis
reduced air spaces
Stomatal crypt
on lower leaf surface to reduce water loss because traps humid air inside crypt
Monocot leaves
all spongy mesophyll
stomata on top and bottom because grass leaves are at an angle and both sides are exposed to light
Bulliform cells
found next to midrib - store water - when loses water leaves fold up in grasses because they are found in dry environments and therefore will transpire less
Epidermal cells in monocots
linear arrangement of cells - dicot is randomly
cells are still integrated to increase strength
C4 plants
have no distinction between palasade and spongy mesophyll
have well developed bundle sheaths with chloroplasts
Krantz anatomy - mesophyll is aranged around bundles
Modified leaves for food storage
bulb underground for root storage
Modified leaves for water storage
leaves are rounded to increase volume and decrease SA to minimize transpiration
sometimes have large epidermal cells to store water
Lithops - stone plant
Modified leaves for defence/protection
cactus - green part is stem and prickles are leaves
Modified leaves for carnivory
venus fly trap
trichomes on surface sense movement and send impule to cells to decrease water content and fold up
other cells secrete enzymes to digest fly - get N and other minerals
Modified leaves for support
pea leaf - has tendrils (modified leaves) to coil around surrounding plant and support its weight
Modified leaves for water collection
epiphytes -plants that grow on top of other plants (problem because not very rooted so need to get moisture from rain - form cup to collect water)
Water potential
Ability of water to do work or diffuse - always moves from high to low potential
Why does pressure develop within plant cells?
When higher solute conc. inside than outside - water moves into cell
Membranes are semi-permeable so allow water molecules in but not solute molecules - therefore pressure builds
when water movement stops because potentials are the same
pressure potential of the cells
Only in cells with rigid cell walls
Primary means of physical supprt in herbaceous plants
occurs when turgor is lost - pressure is lost
use water pressure within body to support their own weight
diffusion of water across a semipermeable membrane in response to a change in water potential
Water movemtent
from the soil through the xylem into individual cells and through the stomata onto the atmosphere - along a water potential gradient
Cohesion-adhesion-tension hypothesis
derived from the idea that water molecules are capable of forming Hbonds because they are polar
H-bonding within water molecules
H bonding between water and matrices - causes them to adhere to the sides of xylem vessles
evaporation of water in leaves pulls the coninuous water column from the leaves down the roots through teh plant
if air bubble develops within system (cavitation/embolism) the whole system falls apart
xylem constructed to avoid cavitation
cells are bigger when formed under wet conditions, but in dry conditions get very narrow because cavitation is more likely to occur - by having narrow diameter can suck up more water
Bordered pits
allow water to move from one xylem to another (around the embolism) but embolism cannot move around pits
How to measure water status of a plant
meausreing the water status of the shoot - by pressure chamber or scharticoff's technique
Pressure chamber
cuts plant stem off and puts in a pressurized chamber - increased pressure in chamber to force water in xylem up to surface - meausre potential of that movement
How do roots maximize water uptake
maximize SA - don't become broad bc have to grow through soil - have long tubular structure one cell thick (root hairs)
Water moves by three routes:
apoplastic - least resistant
movement through the nonliving portion of pant body (cells walls and intracellular matrix)
movement through interconnected cytoplasm of cells in the plant body; plasmodesmata
movement from cell to cell passing through vacuoles of each
Apoplastic route ends
at the endodermis
When reaches the endodermis
there are waxes (suberin) and has to travl symplastic route - advantage is to control what goes in and out of cell
Mineral nutrients are absorbed
at any point - energy requiring process - bc have a higher conc. in roots than in soil and therefore are moving against a conc. gradient
As amount of light decreases
rate of mineral uptake decreases - runs out of energy
When have a higher solute concentration inside root than outside root
leads to osmotic uptake of water and the buildup of pressure in the root under conditions of low transpiration - pressure developes inside central vacuole colum -only at night
Root pressure
only occurs at areas of low transpiration and does not account for movement of water in xylem under normal conditions
process that relieves excess pressure in the xylem at night - water comes out of pore in epithelium called hydathode
Conditions when water moves from plant into soil
at night because stomata are closed - roots are in two different parts of soil(large tree)
Hydraulic lift
when some roots are in ground water and some in dry soil - water leaves tree at higher ground into dry soil
Evidence of assimilate transport
when tree is girdled can transport water from roots to shoots - but can't transport sugars because phloem has been removed
Characteristics of phloem transport:
can occur in two directions (depending on where in the plant you are)
area of high assimilate concentration (leaves)
areas of low assimilate concentration (roots, meristems)
sinks because they are respiring constantly - are reproductive organs - are growing rapidly
Assimalate trasport
very rapid - 50-100 cm/hour
Pressure flow hypothesis
Sources and sinks are always in phloem
- water moves from low to high solute concentration
Passive process - but we know it requires energy
Phloem Loading and unloading
energy requiring process
6CO2 +6H20 --> 6C6H12O2 + 6O2
Light that plants can use in photosynthetic process
visible light - 400-700 nm
leafs reflect GREEN light
photosynthetically active radiation - measured in micromoles - measures the number of particles of protons
chlorophyll a and b and various carotenoids (carotenes and xanothytes)
Chlorophyll a
red light and blue light
porphyrin ring containing N and Mg and hydrophobic tain
chlorophyll b
blue light and red light
has CHO bond in place of CH3
violet and green and yellow light
cleaved in center to give to VA molecules (beta carotene)
VA is converted to retinol
have OH group on rings
responsible for colour of corn kernals
Where does light dependent reactions take place?
mesophyll cells of leaves - not in epidermal cells
all are interconnected to each otehr
all pigments are found in thylakoid membrane - light dependent takes place within the thylakoid membrane - light independent within the stroma
collections of pigments - usually 200-300 molecules
pigments are found in antennae
have two parts - antennae and rxn center
rxn center
only has two chlorophyl molecules
Purpose of pigments in antennae
to absorb light over a broad wavelengths and convert all t o one type of light - rxn center only absorbs either 680 or 700
Energy of a photon is called
a quantum
when photons fall back down to lower energy level and reemit light - not 100% efficent
Longest and shortest wavelength
blue light has shortest wavelength - red light has longest
nicotinamide adenine diphosphate
can accept electrons
Difference between photophosphorillation and respiration
in ppl use light energy, non cyclic, electrons used over and over
respiration use O2
products of light dependent rxns - then go on to other photosynthetic processes
Problem with Z-scheme
produces same ATP as NADPH, but subsequent reactionsneed more ATP than NADPH - therefore cyclic comes in
does not get electrons from water - PSII is not involved
not as efficient
Cyclic takes place
in the mesophyll within the thylakoid membrane - NOT within the stroma
starch is stored within the chloroplasts
the synthesis of ATP using an electrical and chemical gradient - occurs in both resp. adn photo - in thylakoid membrane
Light independent reactions
calvin cycle
converts energy to sugars using energy produced in light dependent reactions
also functions as an oxygenase (can load O2 to RuBP as well as carbon)
Oxygen is
a competitive inhibitor of photosynthetic process - under low CO2 conditions this is a problem
Conditions that enchance oxygenase activity and photorespiration process
high light
high temperatures
water stress
Rubisco cannot
distinguish between O2 and CO2, so sometimes adds an O2 molecule to RuBP to get 1 PGA and 1 phosphglycalate
takes O2 to get CO2 - occurs in light only, does not give ATP
Converts phosphoglycalate to PGA
evolved in hot dry conditions
plants do not use Rubisco but PEP carboxylase - never functions as an oxygenase
C4 pathway gives off...
CO2 wich then goes to the cabon cycle
In order for the C4 pathway to work
there has to be spatial separation between initial and final fixation of CO2 - so occurs in the bundle sheath and mesophyll
How do C4 plants avoid photorespiration?
mesophyll chloroplasts fix CO2 which the goes to bundle sheath chloroplasts - have a high CO2 concentration so Rubisco will never function as an oxygenase
Mesophyll vs. Bundle sheath
granum are extremely well developed in mesophyll - less well developed in bundle sheath but more stroma
CAM pathway
identical to C4 pathway
oxaloacetates and malates accumulate
temporal separation between initial and final fixation
all occurs within one cell
CAM plants
live int he desert
diurnal acidity levels
all store water within their leaves
NO Krantz anatomy
Night vs. day
C4 takes place at night
Calvin cycle takes place during the day
Temporal separationa advantage?
Stomata are open at night to so the transpiration rate at night is lower than during the day - thereofre there is decreased water loss
Difference between C4 and CAM
phosphenol pyruvate in CAM comes from stored strach instead of reactions as in C4
largely aquatic, photosynthetic organisms
most are microscopic/single celled
Algae belongs to two separate kingdoms
prokaryotae and protista
Kingdom Protista
includes: animal like, fungus like, and plant like species
Groups of photosynthetic protists:
900 species
mostly heterotrophs
chlorophylls a, b, and carotenoids
2 unequal flagella
no cell wall but have pellicle
Carb reserve
Origin of Eukaryotic cells
photosynthetic or aerobic prokaryotes englufed by phagocytosis and persists as endosymbionts
outer membrane and inner membrane
outer - food vacuole
inner - plasma membrane of prokaryotes
Chloroplsts of euglenophyta
have three membranes
Rhodophyta (red algae)
4000-6000 species
chla, phycobillins, carotenoids
no flagella
mostly marine
Cell wall
cellulose embedded in a matrix of mucilaginous algin, plasmadesmata in some
Life cycle
gemetic life cycle
spends most of its time in the gametophyte generation
Dinophyta (dinoflagellates)
2000-4000 species
cha, c, and carotenoids, some heterotrophic
one transverse and one longitudinal flagella
cellulose plates beneath cell membrane
produce deadly toxins
Three known stages in life cycle
biflagellated cell
amoeboid stage
amoeboid cyst
100,000 species
heterotrophic and autotrophic w/ cha,c and carotenoids
cell wall composed of silica
no flagella
unicellular or colonial
Carb storage
Centric and pennate diatioms
centric - radially symmetical
pennate - bilaterally
cell walls of diatoms
composed of silicon oxide
consists of two overlapping halfs
contain many pores and channels in ornate paterns
Diamotaceous earth
earth compose of shells of these diatoms
Asexul reproduction
diminishing reproduction
when divides in two halfs pulls apart - can only reconstruct bottom part - one will be the same size as parent and one will be smaller - when becomes so small can no longer make a viable cell then undergoes meiosis and goes to sexual reproductoin
Phaeophyta (brown algae)
1500 species
cha,c and focoxanthin
two flagella in reproductive cells
truly multicellular
three parts of body
where meiosis takes place to produce the egg
where meiosis takes place to produce the sperm
gametes are the same, both move
call + and - mating strands
one large motile and one small motile
one small motile and one large immotile
haploid and diploid generation are different
Chlorophyta (Green algae)
gave rise to otehr species of higher plants bc have same chlorophylls (a,b) and same cell walls and store starch the same way
Cell walls
cellulose, glycoproteins, noncellulose polysaccharides
Three major classes of green algae
motile and non motile
colonial and unicellular
largest class
resting state of zygote with thick cell wall
isogamous life cycle
+- mating strains
do not equal gametes
but form gametes
the joining of the cytoplasm of two cells
Class Ulvophyceae
mostly marine
siphonous - no cell walls connecting adjacent cells
composed of flat sheets of cells
meiosis occurs in
the sporangia to produce spores
most similar to land plants
unicellular, filimentous, parencymal, and colonial generations
unicellular forms, freshwater
constricted cells - have a rigid shape like diatoms
circular, coiled chloroplast
has +- mating strains, makes a zygospore
Chrysophyta (Golden brown algae)
1000 species
cha,c and carotenoids
no flagella or 2 apical flagella (1 tinsel and 1 whiplash)
no cell wall or silica scales
Green algae and plants similarities
photosynthetic pigments (cha, c and carotenoids)
store carbs as starch
cellulose is major component of cell walls
cell division is similar - formation of cell plate
chloroplasts have thylakoid membranes staked into grana
Plants evolved in terrestrial environments
characteristics are adaptatiosn
angiospermsa are best adapted plants to dry environments
Problems terrestrial plants face
obtaining enough water -roots
transporting water from soil to above ground parts and photosynthate to below ground parts - vasc. system
prevent excessive water loss - cuticle and stomata
support plant body - sclerenchyma
exchange gases - stomata
Reproduction in terrestrial plants
don't have flagellated cells so have wind or inset pollination
Four types of terrestrial plants
mosses and other bryophytes
fern and fern allies
need to be moist because have flagellated sperm cell
lack well developed vasc. tissue so can't get very large
have rhizoids for water and nutrient absorbtion
multicellular sex organs with a layer of sterile cells to protect from dessication
gametophyte dominant - sporophyte parasitic
means it has a two dimensional strcution - thalloid liverwort
stemlike structures produced on top of liverwort where sperm is produced
Pores (stomata)
when bryophytes have a cuticle they have pores - which are multiple layers of guard cells but have same function as stomata
Anthocerophyta (Hornworts)
have thallus and long horn like structure growing up
are sporophyte, parasytic on gametophyte generation
Bryophyta (mosses)
two growth forms found: cushiony and feathery forms
Germination of mosses: why related to green algae
when spores first germinate form a structure that resembes a green algae (protonema) - then forms a bud which becomes a gametophyte
Gametophyte stage
is dominant
sporophyte is parasitic on gametophyte stage
Primitive conducting tissue
epidermis, cortex and conducting strand - has hydroids in middle and leptoids outside (start of evolution of xylem and phloem)
Sporophyte generation
produced inside archegonium and absorbs nutrients
has sporangium
falls off and spores are released
Guard cells
only have one guard cell with two different nuclei and a single stomata inside
Seedless vasc. plants
fern and fern allies
protective sterile jackets around reproductive organs
multicellular embryos in archegonium
cuticle on above ground parts xylem and phloem
dominant sporophyte
all have true stems
Dominated Earth
during the Silurian period
grew woody in carboniferous period
generally smaller
grows as an outgrowth of the stem that was vascularized but only have a SINGLE vasc. strand
leaf developed from an entire branch - arranged in 2-D space perpendicular to light to maximize light interception
has well developed vascular system
only one type of spore produced - gives rise to sporophyte generation
have separate male and female spores which gives rise to antheridia and archegonia
only two living genera - Psilotum and Tmesipteris
resemble earliest land plants in terms of structure - lack true roots and leaves and have dichotomous branching
reduction evolution
subterranean generation - because wants to find a moist place
not parasitic
Gametophyte generation
only has rhizoids
no vasc. tissue
sperm are flagellated
major advantage over psilotum, they are leaves which bear sporangia on surface - gives rise to seeds
groups of sporophylls clustered together in a club
can grow in very dry environments
called the quill plant because of quill-like microphylls
have a cuticle but lack a stomata - they are CAM plants - take CO2 through roots and transport it as inorganic acid
arose during Devonian period
only 1 genus - Equisetum
unchanged since carboniferous
found in moist, damp places
hollow jointed stems with whorled microphylls
Souring rush
Underground rhizomes with adventicious roots
Scouring rush
collects silica from soil and deposits it in leaves - leaves have sandpaper like texture
stem that is specialized for reproduction
coiled around spores, are hygroscopic meaning they absorb moisture from air - as gain or loose moisture either coil or uncoil regulating the release of spores
Pterophyta (Ferns)
Arose in devonian and became important in carboniferous
11,000 living species
well developed vasc. - true roots, leaves, and stems
mostly homosporous
Leaves (Fronds)
developed on the undersurface of leaves and are grouped into sori
Ostrich ferns
only ferns that can be eaten
fiddle heads
covers the sori - sporangia are found underneath
outer wall of sporangia - as sporangia matures annulus dries out and eventually cracks open with force to disperse spores
Seed plants share certain traits:
all are heterosporous
megasporangium protected by integuments
gametophyte generation no longer free living - parasitic on sporophyte
dont need water for reproduction
all have megaphylls
Evolution of seed plants
did not become important until permian and triasic period - surface of earth was covered by shallow seas in carboniferous
climate cooled and water levels fell at this time
What are seeds
multicellular sporophyte embryo
food reserve for germination and establishment
outerprotective covering
Ovules include
megasporangium - where magagametopyte is produced by meiosis
Ginko biloba
has separate male and female generations
Pine life cycle
sporophyte (2n) produces male and female cones on different parts of the plant
females produce seeds that disperse and are heavier - males produce pollen which is lighter bc doesn't require much height
Why separate places?
To ensure cross polination and dispersal takes place
Male cone
groups that have sporangia on surface
Female cone scales
ovuliferous scales
cone contains stem and leaf material
After meiosis in males:
microspore divides by meiosis to produce 4 haploid cells - pollen grain (male gametophyte gen)
4 cells of male gametophye
tube cell - ensures growth of pollen tube
2 prothalial cells - degenerate
1 generative cell - divides to produce sperm
air bladders
pollen grain has two air bladders to increase SA to allow it to be carried by wind
After meiosis in females
4 megaspores produced - 3 die and only one functional one - gives rise to the female gametophyte generation
exudes moisture that binds pollen grain
once pollen grain has landed produces tube = once grown generative cell divides
undergoes MITOTIC divisions to produce many cells - some archegonia which have eggs
Once eggs have developed...
the spermitogenous cell divides MITOTICALLY to produce sperm which fuzes with the egg
After fertilization
fertilized egg divides MITOTICALLY to produce embryo
Seed strucutre
has female gametophyte tissue (n) - food storage
embryo - 2n
integuments - forms seed coat (2n)
have multicellular reproductive structures (sporangia and gemetangia) that are surrounded by a layer of residual sterile tissue
All bryophytes are
Moss gametophyte
grows from an apical meristem that consists of a single apical cell
leaf-like structure of mosses
one cell thick - no vasc tissue
- only have cuticle on upper surface
Hydroids resemble
traechids - but with no lignin of SCW
when have no hydroids water moves along the outer surface of the plant
Leptoids resemble
sieve cells - sugar transport
absorbs 20x its weight in water
formed by the germination of spores
heart shaped gametophyte in pteropyhyta
Gymnosperm wood
soft wood with traechids
Where is the ovule produced
develop on exposed surfaces of a modified leaves or braches
Seed differences in gymnosperms
not surrounded by a fruit wall
does not have endosperm - gets food from female gametophyte
Staminate cones
male cone
small and short lived
scales are modified leaves - microsporophylls that have two sporangia on each scale
Seed cone
ovulate cone
has ovuliferous scales - has two megasporangium

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