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BIO 35-37


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Root system
Abosrption of water, minters from the ground
large, vertical root
site of photosynthesis, where the sugar is made
long, thin tapered at end (called pits which allow the water and minerals to flow from cell to cell)
Apical meristems
(buds/apex tips of shoots, roots) elongation, or branching that takes place (primary growth)
Fibrous root
fine, lateral roots
area on the steam where leaves are atached
waxy layer on both sides of the leaf with most on the top side (prevents water loss)
Vessel elements
short, stout, no pits, and are stacked upon one another with perforated ends (pits and perforated ends allow water and minerals to pass from cell to cell)
Cork cambium
produces cork cells, which produce the outer layer (bark) of the plant; cork cells form the majority of the bark
cells to cell via plasmosdesmata (fast)
region between the nodes
tiny pores which allow gas exchange (always on the bottom of leaves to prevent water loss)
Food conducting cells of Phloem
transport of sap (sugar)
Lateral meristems
only found in woody plants, encourages secondary growth (thickening or widening of the plant)
traveling through the matrix of cell wall pores (fast)
Transpirational pull
transport of xylem sap
Solar-powered bulk flow
Sunlight causes the evaporation of water molecules from stomata and this creates a negative pressure (tension) which pulls the entire water column upwards
Plant adaptations to arid climates
Thick cuticles to reduce rate of transpiration (reduce water loss); stomata usually located in pits on the underside of leaves
Sugar source
part of the plant that makes sugar through photosynthesis or the breakdown of starch (usually mature leaves)
Mechanism which loads sugar into sieve tube members from the source and unloads sugar into the sink
(needed in large amounts)

C, N, O, H, S, K, P, Ca, Mg
Nitrogen fixation
plants need Nitrogen in the form of Nitrate (NO3) or Ammonium (NH4)
certian plants which have roots swellings (nodules) that contain these bacteria in a mutualistic relationship
a photosynthetic plant which obtains xylem sap from its host plant
Root hairs
(on all roots) increases surface area for absorption
Adventitious roots
roots originating from above ground
contains photosynthetic cell (in a leave: cuticle / mesophyll / cuticle)
Sieve-tube members
alive at maturity but lack most organelles, ends are connected via the sieve plate
Apical dominance
terminal bud inhibits the growth of the axillary buds
Zone of elongation
cells are lenghening, which pushes the root into the soil
Order of cross-cut
Xlyem -> Phloem -> Vascular Cambium -> Cork Cambium
layer of cells that surround the xylem, last checkpoint for water and minerals (screen for apoplastic route)
water loss from the stomata in leaves
guard cells
Form the stomata and regulate the opening/closing
Transpiration-to-photosynthesis ratio
How much water is lost per gram of CO2 fixed into sugar (Calvin cycle)
Sugar sink
whatever consumes or stores sugars, e.g. carrots/fruits
Pressure flow in sieve tubes
Low water potential in phloem at the source causes an influx of water. The high water pressure drives the flow of sap from source to sink
(needed in small amounts)

Zn, Cu, Mn, Mo, B, Ca, Fl, Fe, Ni
Mutualistic relationship between fungus and the roots of plants (fungus get sugar, plants get more S. area)
a type of plant which doesn't photosynthesize, instead it derives all its nutrition from its hostp lant by tapping into its phloem
Shoot system
Made up of stem and leaves
axillary bud
Found in the angle between the leaf and the stem, usually forming branches
Specialized plant cells (2)
Xylem / Phloem
companion cells
Direct metabolism of neighboring sieve-tube members, connected to members by plasmosdesmata
Root cap
bottom of root, protects the apical meristem as it enters the soil
Zone of maturation
cells begin to differentiate and become specialized
3 main substances transported in plants
Water, minerals, sugar
Root hairs and mycorrhizae
Create surface area for abosrption of water and minerals (initial entry point)
bonding of water molecules with each other
When water floods in, the stomata...
Loading and unloading of sugar
Sieve-tube members accumulate a high concentration of sugar from mesophyll cells
What are the three things that plants require for their nutrition?
CO2, water, minerals (sunlight does not provide nutrition)
How do clay particles prevent leaching of positively charged minterals such as K or Ca?
(clay is negatively charged) ... They tend to bond cations to the soil, so root hairs to cation exchange because clays won't give the cations up
Nitrogen fixing bacteria convert...
N2 to NO3 in the soil
Parasitic plants
plants which drain resources from other plants
Carnivorous plants
Found in acidic environments that have nitrogen poor soil; they need to supplement their nitrogen intake from insects caught in their traps (make their own carbohydrates, though)
Parts of stem
Nodes, internodes, axillary bud, terminal bud
Terminal bud
at the apex (top) of the shoot (allows for vertical growth)
Water conducting cells of xylem
cells that ranspore water and minerals (dead at functional maturity, forms the wood of plants)
embryonic plant tissue that is actively dividing
Zone of cell division
meristematic tissue is formed
vascular cambium
secondary xylem and phloem
Lateral transport routes in plant
Tran-membrane: cell to cell via repeated crossings of membranes in walls (slow)
Mineral screening (2)
Endodermis / Casparian strip
Casparian strip
waxy belt that surrounds the cell walls of endodermal cells. Prevents unwanted minerals (ions) from entering the xylem through the apoplastic route
water molecules bonding with the xylem (water w/ non water)
Translocation of phloem sap
How does sugar move
Essential nutrients
nutrients essential for the growth of platns
Cation exchange
The roots release CO2 which generate carbonic acid which displaces cations and allows them to be absorbed by the roots
Development of male gametophyte in antiosperms
within the pollen sac (anther), diploid cells undergo meisos to produce microspores (4 microspores):

microsporophyte->4, microspores(n)->mitosis->generative cell, tube cell=pollen grain
Development of female gametophyte in angiosperms
megasporophytes located in ovules undergo meiosis, producing 4 megaspores:

megaspore: haploid->mitosis (3x)->3antipodal cells, 2 polar nuclei, 1 egg cell, 2 synergids
Egg cell
female gametophyte, waiting to be fertilized
attract and guide the pollen tube
Anipodal cells
function unknown?
Polar nuclei
give rise to the endosperm
wind, insects, birds, bats, etc.
Preventing self-fertilization
temporal frequency (pollen is released prior to the development of receptive stigma), self-incompatibility (plant's ability to recognize self and reject their on pollen)
Double fertilization
After the pollen grain germinates upon the stigma, a pollen tube quickly grows in the direction of the egg cell. The generative cell divides into two sperm. Sperm #1 fertilizes the egg, sperm #2 combines w/ the polar nuclei (development of the endosperm)
Endosperm development
storage of an energy-rich nutrient supply available to the plant upon seed germination
Embryo development
zygote->mitosis->multicellar embryo complete w/ meristems
Mature Seed Structure
seed will dehydrate itself, embryo growth comes to a stop, enters a state of dormancy
Development of fruit ovary
fruit aids in dispersal of the seed, ex. apple orange (fruits have seeds, vegetables do not)
Seed germination represents the continuation of growth
Environmental factors affecgts when a seed will germinate, ex. water, amount of light, temperature (responds to both hot and cold), and extreme heat (i.e., after a fire)
Asexual Reproduction
production of offspring from a single parent resulting in clones
Vegetative reproduction
separation of parent into parts that reform whole plants (plants have the capability of indeterminant growth, which is the result of meristems producing undifferentiated cells capable of devloping into roots, leaves, and shoots)
production of seeds w/out meiosis or fertilization (megasporophyte undergoes mitosis, so instead of 4 megaspores, there are 2, which develop into seeds, i.e., dandelions)
Benefits of sexual reproduction
genetic variation, produce seeds to inhabit another locale upon dispersal, provides raw material for evolution
Benefits of Asexual Reproduction
make many copies in a short period of time, fragments are a mature part of the plant and not a fragile embryo, working model retained
Responding to environmental stimuli via signal transduction pathways
the way of getting a message from outside the cell to the inside of the cell
greening in a new shoot growth
reception, transduction, response
the detection of an environmental stimulus or chemical signal at the cell surface
pigment protein complex that undergoes a conformational change in the presence of light
two main ways: transcription regulation, post-translational modification
Transcription Regulation
Inducing transcription factors to transcribe the necessary genes for greening
Post-translational modification
Activating existing proteins to carry out the necessary cellular activities involved in greening
Plant Hormones
Hormones are chemical substances that are produced in one part of the body and have an affect on another area w/in that body
Darwin's experiment
tip of the shoot was responsible for detecting light
a response to environmental stimulus (can be negative or positive)
tropoism w/ light
Boysen-Jensen Experiment
a chemical message is produced in the tip and produces a protein for growth (gel experiment)
F. Went's Experiment
(discovered first hormon Auxsin, which stimulates cell growth) Agar at the top of a shoot is saturated by the substance auxin, and it leaked into one side of the shoot and caused it to grow on that side
produced in the apical meristems, embroy of the plant, and young branches; EFFECT: low [] stimulates cell growth, promotes development of fruit, promotes adventitious root growth
Produced at the roots, move up through xylem sap; EFFECT: stimulates cytokinesis, w/ auxin they provide for apical dominance
Produced at teh apical meristems, embroy plant and young leaves; EFFECTS: internodal growth, stem elongation, fruit development, seed germination
Abscisic Acid (ABA)
Produced at the leaves, stems, roots, unripe fruit; EFFECT: suspend seed germination, increasing peiod of dormancy (ABA vs. Gibberellins)
Produced at ripening fruit, aging leaves; EFFECT: fruit ripens, leaf abscission (when leaves fall to conserve H20)
Produced at the seeds, stems, shoots, leaves, buds' EFFECT: inhibits root growth, delays leaf absiscion
Plant Response to Light
light is no only impotant in photosynthesis; it aloso regulates a # of plant processes
The role of phytochromes in photoreception
chromophore: exists in 2 isometric forms

Form 1: Pr->exposed to 660nm (red)->Pfr form
Form 2: Pfr->exposed to 720nm (far red)->Pr form
Circadian Rhythyms
physiological cycle based on an internal clock, not environmental stimulus
Setting the clock
plants use the ratio of Pr/Pfr to set their clocks

ex. Sun rises, Pfr increaes, Pr decreases
regulation of physiological processes by the photoperiod
the amount of sunlight in one day
Short day plant
requires a photoperiod shorter than its critical period to flower (long night)
Long-day plant
requires a photoperiod longer than their critical period (short-night plant)
Day-neutral plant
flowers regardless of photoperiod (when they reach maturity)
Critical night length
1940-discovered it's actually the amount of continous darkness that stimulates a plant to flower; regulated by the ratio of the amount of Pr and Pfr
Role of hormones
Phytochromes detect photoperiods and relay the message to the flowers via the hormones
Response to gravity, roots down, shoots up...statoliths=plastis containing dense granules of starch regulate this
Mechanical stress (agitation, shaked, etc.), will stunt primary growth and increase secondary growth
close stomata, slow new growth
xylem tissue will undergo apoptosis (cell suicide)---creates an O2 pathway from bottom to top
Salt Stress
more ions outisde, therefore water diffuses out, so the plant increases synthesis of organic compounds in order ot decrease the water potential
Heat Stress
close stomata, produce heat-shock proteins (resist denaturation), therefore plant keeps its shape
Cold Stress
in cold, increases fluidity of cell membrane by increasing the # of unsaturated phospholypids (& changes solid concentration)

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