MCDB 1B Final
what makes up the cell wall
25-30% cellulose (major structural component) 40-55% other polysaccharides (such as pectin and hemicellulose for additional structure (interwoven between cellulose) 1-15% protein
what is needed per 1 CO2 and when is this used
3 ATP and 2 NADPH 2 ATP used in step 2 2 NADPH used between step 2 and step three to go from 3PG to 1,3 BPG 1 ATP used for step 3
real name of 3PG, 1,3BPG, G3P, RuBP
3-Phosphoglycerate 1,3-Biphosphoglycerate Glycerol-3-phosphate Ribulose 1,5-bisphosphate
Cotyledon
A "seed leaf" which develops as a part of the seed. It provides nutrients to the developing seedling and eventually becomes the first leaf of the plant.
What is cellulose
A LINEAR glucose polymer with lots of H-bonding potential Microfibrils of glucose are composed of 30-25o linear molecules of glucose hydrogen bonded together polysaccharides cross link these microfibrils together
Q: Which statement about the Calvin-Benson cycle is NOT TRUE: CO2 reacts with RuBP to form 3PG RuBP forms by the metabolism of 3PG ATP and NADPH + H+ form when 3PG is reduced The concentration of 3PG rises if the light is switched off Rubisco catalyzes the reaction of CO2 and RuBP
ATP and NADPH + H+ form when 3PG is reduced
what provides energy for symplastic uptake of minerals at casparian strip
ATP hydrolysis pumps protons in which then creates a pl1) H+ pump forces H+ into the cell wall which makes this acidic and sets up concentration gradient 2) cations move from high to low concentration (aka inside the cell) - one example of this is K+ which simply diffuses into cell bc of the gradient (also can cotransport neutral solutes; important for sugar) 3) Anions move down the gradient (follow cations) into the cell via H+ symport
Requirements for photosynthesis
Access to CO2, light, and pigment to absorb light energy
what reaction center is Photosystem 1 and which is Photosystem 2
1: P700 2: P680
what type of regulators are ethelyne receptors and what are they
2-component regulators sensor and response regulators
how long is a plant circadian rhythm and what controls it
24 hours PHYs and CRYs help to entrain the plant biological clock
Which of the following factors has a direct impact on the orientation and expansion of plant cells Initial cellulose microfibril orientation Turgor pressure Lignin deposition All of the options influence cell growth
All of the options influence cell growth
Q: in noncyclic photophosphorylation, the chlorophyll in photosystem I is reduced by
An electron from the transport chain of photosystem II reduced means it gains an electron
Which classical hormones (+ BR) inactivate the repressor
BR
steps of brassinosteroid signalling (and what happens when too much BR)
BR binds to receptor --> phosphorylation cascade --> inactivation of repressor --> BR regulated gene expression Negative feedback regulation comes when there is too much BR so you put repressor back on to inhibit its synthesis
Q: Why do greenhouses use purple light for plants
Because chlorophyll primarily only absorbs red and blue light so that's all it needs
is recognition of plant hormones intracellular or extracellular? why example of one receptor that is cytoplasmic in animals but is not in plants
Both! Most plant hormones can cross the cell membrane but don't necessarily have to, just depends!! yay! so confused abt this! steroid receptors are in animal cytoplasm but brassinosteroid receptors are membrane bound
Any side shoots on the main stem of a plant are most likely to originate from: a. cell division in a tissue call the pericycle b. lateral meristems between the xylem and phloem c. buds in the axils of the leaves d. migration of cells from the apical meristem e. outward bulges from epidermal cells
C Any side shoots on the main stem of a plant are most likely to originate from: [buds in the axils of the leaves]
What version of the calvin cycle can every plant go through (name)
C3
in what cells do C3 reactions take place vs C4
C3: All the steps of dark reaction take place in mesophyll cells. C4: The initial steps are carried out in mesophyll cells and the subsequent steps are carried out in bundle-sheath cells.
C3 leaf vs C4 leaf
C4 leaves are characterized by Kranz-type anatomy, in which the vascular bundle is surrounded by bundle sheath (BS) cells and this tissue layer is further surrounded by radially arranged mesophyll cells. In contrast, C3 leaves have mesophyll cells that are well developed relative to the Bundle Sheath cells.
What happens in step one of calvin cycle (reaction, does it require energy, what else does it require, how many are produced)
Carbon fixation aka carboxylation 3 CO2 and 3 RuBP combine with the enzyme rubisco to form 3PG (there are 6 of these) 3PG is 3 carbons and a phosphate at the end; 2 of these for every 1 CO2 no energy required input of CO2 required
GA (receptor locations, steps of GA message - including what id does to messenger -, and what this causes)
Cell Surface Receptor Nucleus Receptor The receptor recieves GA and releases Ca2+ and cGMP - Ca2+ causes release of amylase - cGMP leads to destroyance of repressor by first tagging repressor with ubiquitin which signals for proteasome to recognize and destroy the repressor this causes the transcription factor which causes amylase to be coded
Which of the following describes the ploidy of the components of a seed? Diploid embryo, triploid endosperm, diploid seed coats Diploid embryo, diploid endosperm, diploid seed coats Diploid embryo, triploid endosperm, haploid seed coats Haploid embryo, triploid endosperm, diploid seed coats Haploid embryo, diploid endosperm, haploid seed coats
Diploid embryo, triploid endosperm, diploid seed coats
where is the ethylene receptor hwo does it get through PM
ER crosses through PM easily by diffusing
types of ethylene mutants and what they cause and why they happen (loss of what kind of regulator)
Ein mutant is not sensitive to ethylene and grows super tall (loss of positive regulator) Ctr mutant is too sensitive to ethylene and grows short (loss of negative regulator)
Which classical hormones (+ BR) don't activate the repressor
Ethylene
Which classical hormones (+ BR) have the same family of 2 component regulators
Ethylene and CK
How is plant growth indeterminate and repetitive
Growth is indeterminate (they don't always look exactly the same) repetitive (make leaf after leaf after leaf and then flowers; every time)
How does rapid growth work in Auxin
H+ pump sends H+ to cell wall which increases acidity which leads to expansion which loosens walls - Auxin fuels this H+ pump and creates it Auxin and H+ go into the next cell like a symport and then H+ goes into the cell wall after this
what is the cycle for acyclic light reactions
H2O is split which produces O2, H+, and an electron This electron goes into Photosystem 2 where its energy gets raised by light The electron goes through the electron transport chain to produce H+ which drive the ATP synthase The now low energy e- goes into Photosystem 1 and gets its energy raised again which produces a high energy electron this high energy electron can combine with NADP+ to create NADPH
PEP carboxylate does not bind ____, it only binds _____
O2 CO2
what is a positive vs negative regulator
Positive regulation is that regulation in which the presence of specific regulatory element increases the expression of genetic information quantitatively. Negative regulation is regulation in which the presence of specific regulatory elements diminishes the expression of genetic information
How does human DNA compare in quantity to plant (arabidopsis) DNA
Humans have 30x more DNA than model plant but similar # of genes This is because so many of human genes are repeated, a trend that tends to happen with higher genome sizes
Long term effects of auxin (where are receptors, what receptor class are these similar to aka what happens)
Receptors in plasma membrane and inside cell cytoplasm they have the same receptor class as GA aka the repressor is destroyed via proteasome
In some dicots, no distinct endosperm can be seen. Why? The cotyledons have absorbed the endosperm. The embryo cells have migrated throughout the endosperm. The endosperm has become the seed coat. The seeds never produced endosperm. The fruit has incorporated the endosperm.
The cotyledons have absorbed the endosperm.
When sugars are actively transported into a cell, what happens to the turgor pressure inside that cell as a result? Decreases, because sugar concentration directly affects turgor pressure No change; sugar concentration has no effect on turgor pressure Decreases, because water exits and affects turgor pressure Increases, because water enters and affects turgor pressure Increases, because sugar concentration directly affects turgor pressure
Increases, because water enters and affects turgor pressure
Q: Plant "action potentials" resemble of those of animals in that:
Ions rush in and depolarize plant; that's about all they are the same
How is cellulose synthesized on the cell surface
Is done by enzyme complexes in the plasma membrane and its associated cortical microtubules
CK (what it causes, receptor location, what family of receptors is it like and how, how is it diff than this)
It causes lateral growth/branching receptor location is in the ER membrane Just like ethylene with 2 component regulator and phosphorylation cascade CK activates receptor and activates repressor (unlike eth)
Ethylene (receptor location, what does it do to repressor and what this causes)
It diffuses through the plasma membrane and has a receptor on the ER It turns off the repressor which is usually activated so that transcription can happen this causes fruit to ripen and triple response in seed
GA (type of hormone, main purpose, how does it work and where, what is one study that proved its function and how)
It is a plant growth hormone that helps seed get food for growth; promotes fruit growth; controls germination positive germination, positive elongation the embryo releases GA into the endosperm which induces the synthesis of amylase to to digest the endosperm and embryo nutrients for the seed "Foolish Rice Disease" showed that GA increases size of internodes in plants and allows positive elongation; the plants not given GA were normal and not tall and spindly like the ones given GA
Composition of ethylene receptor, structure of this, and what this is similar to
It is related to a family of closely related proteins called "2 component regulators/receptors" signal goes into variable input, through conserved area, across gap, through another conserved area, and a response comes from the output of a variable area CK is also part of this family
Photosynthesis 2 steps (what are they, where do they occur, what do they produce)
Light reaction - thylakoid membrane of chloroplast - convert light to chemical energy (ATP + NADPH) Dark reaction/Calvin Cycle - stroma of chloroplast - converts CO2 to Glucose Sugar (C6H12O6)
what are the two types of xylem vascular tissue and what do they do
Tracheids - longer and skinnier and are the main xylem in angiosperms (flowering plants) Vessel elements - shorter and wider and found in older plants
Q: Which of the following causes tension in the xylem fluid? Transpiration at leaf surface Cohesive nature of water Narrowness of xylem tube All of the above
Transpiration at leaf surface the others allow it, but don't cause it
what causes cell wall growth and what causes how it grows
Turgor (aka hydrostatic pressure - water pushing against walls) vacuole is what expands to create pressure growth direction is perpendicular to cellulose microfibrils in the primary cell wall
Q: The triple response of seedlings... Usually occurs underground in nature Occurs in all seedlings grown in dark Is mediated by pessure induced synthesis of brassinosteroids Includes radial swelling of stems due to primary horizontal cellulose deposition
Usually occurs underground in nature Is mediated by pressure induced synthesis of brassinosteroids - Its ethylene instead Includes radial swelling of stems due to primary horizontal cellulose deposition - Its vertical
Q: Gibberellins stimulate production of alpha-amylase Only in the same tissues where GAs are produced Via promotion of transcription and secretion And this effect is antagonized by auxin
Via promotion of transcription and secretion
If the xylem sap is under tension (up to 25 atm), why don't cells collapse?
Xylem cells have highly reinforced secondary walls
what is the structure of a photoreceptor
a dimer of protein + chromophore
How does a cell wall form in a dividing cell
a dividing cell has its normal membrane, then a primary cell wall, then a middle lamella growing around this there is a cell plate in the middle where the vesicles coalesce to form more of the middle lamella in between The two daughter cells secrete wall material at the plasma membrane surface, creating the secondary cell wall
absorbtion vs action spectra
absorbtion: show which wavelength are absorbed by a given molecule action: show which wavelengths are affected for specific process GREEN IS REFLECTED BY CHLOROPLAST and so it is never absorbed and is only actioned upon sometimes
how does auxin promote cell elongation (2 ways) and aspects of each ot these
acidic rapid wall loosening (increased plasticity) - auxin promotes secreting H+ protons decreasing wall pH, low pH makes proteins disrupt bonds btwn polysaccharides, microfibrils thus can slide past eachother long term effects (continued wall and membrane synthesis)
Auxins cause elongation by: triggering proton release. indirectly increasing plasticity. indirectly activating expansins. All of these None of these
all of these
Ethylene (select all that apply) induces primarily longitudinal cellulose deposition in seedlings regulates diverse processes in plant growth including the "triple response" of seedlings, fruit ripening and leaf drop synthesis is induced by pressure and ethylene, but repressed by light
all: induces primarily longitudinal cellulose deposition in seedlings regulates diverse processes in plant growth including the "triple response" of seedlings, fruit ripening and leaf drop synthesis is induced by pressure and ethylene, but repressed by light
Auxin transport (select all that apply) produces the auxin gradients required for establishing root-shoot polarity early in embryogenesis polarity is conferred by basally localized efflux carriers on individual cells is polar: from shoot tips toward root tips
all: produces the auxin gradients required for establishing root-shoot polarity early in embryogenesis polarity is conferred by basally localized efflux carriers on individual cells is polar: from shoot tips toward root tips
what is GA antagonized by
amylase
A graph that plots the rate at which carbon dioxide is converted to glucose versus the wavelength of light illuminating a leaf is called
an action spectrum.
Antiport vs Symport
antiport is when one ion goes in and one goes out symport is when two ions go in as a couple
two types of buds found in shoots
apical bud: most of young shoot growth is found here axillary bud: can potentially form a lateral branch from a leave on a stem
apoplast vs symplast
apoplast: everything external to plasma membranes including cell walls, extracellular space, and interior of dead xylem cells symplast: entire mass of cytosol of all living cells in a plant as well as plasmodesmata
what are the three roots of transport within a plant
apoplastic route (waters and solutes move along cell walls and extracellular space) symplastic route (waters and solutes move along continuous of cytosol transmembrane route: water and solutes move out of one cell, across cell wall, into next cell
Plant growth substances generally: are species-specific. are produced in many parts of the plant. affect mainly the cells that produce them. elicit only rapid responses. have a single specific role.
are produced in many parts of the plant.
You have installed an outdoor gas burning grill on your back patio next to your favorite camellia bush. After the first few chilly nights of using your grill you notice that your camellia, which does not normally lose its leaves, is beginning to do so. Which of the following is the best explanation for what is happening? Ethylene is a by-product of the gas you are burning and is causing senescence in your plant. The plant is a biennial and is bolting. The bush is getting too warm next to your grill. Abscisic acid is a by-product of the gas you are burning and is causing senescence in your plant.
Ethylene is a by-product of the gas you are burning and is causing senescence in your plant.
Q: Stomatal aperture is regulated by: A. Light B. ABA C. K+ and water movement between guard and subsidiary cells, primarily via plasmodesmata D. A and B E. A, B, C
D. A and B not C because K+ and water movement go through channels, not through plasmodesmata
what are 3 major tissue types of plants and where are they
Dermal (outermost layer) Vascular (inside of dermal, changes position throughout) Ground tissue (everything not dermal or vascular)
what type of signaling occurs from GA
G-protein coupled signaling aka secondary messenger signaling
Difference between G3P and 3PG
G3P has an aldehyde 3PG has a carboxyl group
Bolting, or rapid stem elongation, is induced by __________ and can be inhibited by __________.
GA ABA
which classical hormones (+ BR) destroy repressor with proteosome
GA and Auxin
Why don't immature seeds degrade their resources immediately
GA levels are low and ABA levels are high during embryo maturation maturing seeds are also not that affected when GA is added to them
5 Classical plant hormones
GA: Gibberellic acid ABA: Abscisic acid Ethylene IAA = Auxine CK: Cytokinin
what is the time called that marks for a certain plant whether it has been a long or short night
called the critical photoperiod
In C4 plants, the function of the four-carbon compound that is synthesized in the mesophyll cells is to
carry CARBON DIOXIDE to the bundle sheath cells.
what is in the roots and what does it do
casparian strip it is waxy and blocks apoplastic movement, forcing only selective material to go into plant cells it is located in the endodermis of roots
what is the order of primary cell walls, middle lamella, secondary cell wall, plasma membrane, etc
cell --> plasma membrane --> secondary cell wall --> primary cell wall --> middle lamella
What are the constraints imposed by the cell wall?
cell position is fixed, no cell migration growth depends on turgor (hydrostatic pressure) to stretch walls cell position affects the cells lineage
what are some plant specific genes
cell wall synthesis, photosynthetic structures, secondary metabolism (dyes, scents, drugs)
Technically, short-day plants flower when the
dark period exceeds a critical period.
auxin response requires ______ of repressors
degradation
GA deficient or non-responsive plants are ______
dwarves
Q: Q: Plant cell walls a. represent an age gradient composed of middle lamella, primary cell wall and secondary cell wall (listed from youngest to oldest). b. are interrupted by plasmodesmata, connections between adjacent cells maintained after formation of the cell plate. c. are secreted or deposited immediately outside the plasma membrane e. b & c only
e. b & c only
movement through cortex of root may be (apoplastic and/or symplastic) and entry into the vascular core (stele) of the root is be (apoplastic and or symplastic)
either symplastic
what form of energy is light what are its units the energy of light is inversely proportional to its ______ high energy = _______ ___________ visable light = __________
electromagnetic energy photons wavelength ionizing radiation 380-750 nm
In both photosynthesis and respiration, protons are pumped across a membrane during
electron transport
Most water moving through the apoplast from the soil into the stele cells first crosses a plasma membrane in the cells of the
endodermis.
cytokines are similar to ______ in that they are a _________ receptor family and are recognized in the ________
ethylene 2 component ER
genetically what does auxin promote
everything bruh Auxin promotes: Embryonic pattern formation Root meristem formation and growth Vascular differentiation Lateral organ initiation Cell elongation Apical dominance
ABA (receptor location and type of signaling)
extracellular (PM) and intracellular (plastid) signalling is in the phosphorylation cascade and G-protein coupled
how was calvin cycle discovered
feed algea radioactive CO2 and label when products are created
florigen is ______ transmissable, even between LD and SD plants
florigen
what is an angiosperm
flowering plant
major events in angiosperm lifecycle
gametogenesis fertilization embryogenesis germination greening vegetative growth flowering
If Red light is the msot recent light, a plant will _______ if far red light is the most recent light, the plant will ________
germinate not germinate
what are processes regulated by light intensity/quality:
germination de-etiolation shade avoidance (plants in shade have a low R/FR ratio and in sun have high R/FR ratio) leaf morphology (submerged plants have higher R/FR ratio)
When dicot seeds germinate below the soil surface, the young seedlings: keep the cotyledons enclosed in a coleoptile. elongate so that the apical meristem is the first part of the shoot to break through the soil surface. produce chlorophyll. have small, unexpanded leaves. grow very slowly.
have small, unexpanded leaves.
what is genetic redundancy
having a large number of duplicated genes
Ethylene (main purpose, what is it sensitive to and how, main purpose, what type of response does it cause - just the name)
helps to ripen fruit light inhibits its synthesis, it produces more in the dark; higher pressure leads to higher synthesis increases senescence (aging) causes triple response in seeds
growing areas in plants have (high/low) water flux because of high count of __________
high aquaporins
what happens with a high CK to Auxin ratio what abt a low one
high: big branchy trees low: tall and straight up trees
In order to transport K+ ions into their cells, plants
pump protons out which creates an ion concentration gradient
what play the primary role in basic transport in plant cells and how
hydrogen ions this causes negative membrane potential it can do cotransport it can drive active transport of solutes
is cellulose hydrophilic or hydrophobic
hydrophilic
Steps to C4 reaction and where they occur
in mesophyll cell PEP and CO2 are combined to create OAA This OAA goes to a bundle sheath cell where it splits into a single Carbon and 3 other carbons (PEP) The PEP goes back to the mesophyll cycle to restart it The single carbon goes in and performs the rest of the Calvin cycle as CO2 (and not O2 as it would've been)
dark reactions can work in the dark, but in real life they always work ________ because...
in the light they are just called dark reactions because light doesn't matter for them to work
Root hairs are adaptations that
increase surface area.
what do root hairs do
increases surface area for absorbtion
Cytokinins ______ sensecence
inhibit
mesophyll
internal ground tissue located between the two epidermal cell layers of the leaf
companion cells to sieve cells in phloem may have wall __________, increase plasma membrane _______ _______, and are also known as
invaginations surface area transfer cells
what is special abt visable light
it can raise electrons to higher energy levels/states
If xylem sap is under tension, why doesn't the water column break and airlock the system?
it does but flow is maintained by a network of vessels connected by pits
When is photorespiration used and why
it is used by plants in arid (dry) environments with less CO2 because the stroma is closed to retain more H2O high temp and high light raise O2 to Co2 affinity because the stomatas close to retain water and so less CO2 is brought in Rubisco binds to O2 and this makes it so RuBP combines with O2 instead of CO2
what is the usual pressure potential within plants
it is usually positive because protoplast (living part of the cell) presses against the cell wall, creating turgor pressure
how does auxin induce bending what is its source
it laterally is redistributed by light and gravity and promotes unequal elongation in tropic growth it is synthesized rapidly in growing parts of plant (shoots)
how does H2O movement work in a plant
it moves down the water potential gradient, from high to low water potential
What type of receptor is a photoreceptor and what is this what activates photoreceptors
its a phytochrome receptor which has light sensing pigment
what season do long night plants flower what is the goal of these long night plants
late fall and early spring (long days) less PFR aka to get more PR
2 types of photoreceptors, what activates them, and what nm of light they perceive)
left perceives 660 nm and right perceives 730
dark reactions can occur during the _______(what time)______ but they need _______ from ______ to occur
light or dark energy light rxn
what closes and opens stomata
light or low CO2 promote opening (bc starving) High CO2 or water stress (signalled by ABA promotes closure)
short night plants have a ____ day and visa versa
long
water potential in air surrounding leaves is much (higher/lower) than that in the plant
lower
what are the stem cells of plants and what are the types
meristems apical meristems --> primary growth (length) lateral meristems--> secondary growth (thickness)
where does the sugar from the calvin cycle go
mitochondria
if the outside of a cell has higher solute concentration, what will happen to that cells protoplast
more negative solute potential and thus more negative water potential outside water from protoplast goes through plasmilysis where it goes outside and protoplast shrinks
what is the ground tissue mostly responsible for
most of the metabolic functions in a plant
what type of pressure and from where allows water and minerals to go from roots to leaves
negative pressure (tension) generated by evaporation from leaves this is in the xylem
without an embryo would GA's be produced
no
do source and sink tissues always stay same
no, as sinks mature they can become sources
Cohesion is the tendency of water molecules to attract
other water molecules by hydrogen bonds.
what transport brings florigin from leaves to apex
phloem
What is florigen regulated by and what is transcription factor
photoperiod (CO is transcription factor so more CO is more florigen)
what is it called when a plant bends towards light
phototropsin
what is pressure potential
physical pressure on a solution can be positive if pushing out water and negative if pulling in water
different aproaches to understanding hormone response
physiological: spray and pray genetic: wreck and check reverse genetics: like RNAi for C. elegans
what are plant hormones called
phytohormones
what process occurs in thylakoids other than light capture and creating ATP and NADPH
pigment regeneration
What part of the plant measures the dark period and how does this communicate to the flowers from here?
plant glorigen
senecence definition
plant aging
what are the two main cellular differences in plants and animals
plants have chloroplasts and a cell wall
What does C4 calvin cycle do and who use it
plants in arid environments use it it replaces step one of the original calvin cycle with an alternate carbon fixation step
Correctly order structures from inside to outside of cell secondary cell wall, primary cell wall, plasma membrane, middle lamella
plasma membrane, secondary cell wall, primary cell wall, middle lamella
what are the permanent connections between primary cell wall of adjacent cells called how do they compare in size to gap junctions what alters their pore size how are they maintained in secondary walls how long do they last
plasmodesmata they are 30x larger in pore size than gap "gating" alters pore size and can change throughout a plants life they are maintained using pit fields (holes around plasmodesmata) in secondary walls they are permanent
is auxin (polar or non polar, vertically or laterally redistributed, in the transpiration stream?, gravity dependant?, faster than diffusion, energyless?, carriers?)
polar movement towards bottom of plant and non polar movement via phloem lateral redistribution not in transpiration stream not gravity dependent yes faster than diffusion requires metabolic energy carrier mediated
cellulose is a type of _________, just it is the main one so it got its own category
polysaccharide
what type of pressure and from where allows sugars to move to where they are needed
positive (turgor) pressure to where they are needed (sugar goes from leaves or roots to places where it is needed) leaves produce sugar and roots store it this is in the phloem
CK (where produced and where does it effect, what does it cause - 3 things - , what is the acid growth hypothesis)
produced at roots but promotes shoot (branching) and fruit growth plant widening, positive lateral growth, negative senescence Acid Growth Hypothesis: - when these hormones are released, they increase proton pump function which increases cell wall acidity in order to activate expansion
Auxine (where is it produced, where does it promote growth, what does it do - 4 things)
produced in the shoots (apical meristem) but promotes root growth Prevents branching and promotes vertical growth positive elongation apical dominance promotes phototropsin
2 Effects of Auxin
rapid (acid) growth and long term growth
what kind of light do photoreceptors respond to
red and blue light same as chlorophyl
NADPH is the _____________ formula of NADP+
reduced
In noncyclic photophosphorylation, water is used for the: oxidation of NADPH. hydrolysis of ATP. synthesis of chlorophyll. reduction of chlorophyll. excitation of chlorophyll.
reduction of chlorophyll.
When white light strikes a blue pigment, blue light is
reflected or transmitted.
Brassinosteroid (function, what happens with a mutant, what is its effect, what is it antagonistic with, receptor location)
regulates etiolated growth (dark growth) which makes plants tall and dark but with no leaves A mutant of this will have too much etiolated growth whcih means tall, dark, no leaves + growth through elongation and cell division antagonistic with ABA receptor location is in the plasma membrane
Induction of response requires inactivation of _________
repressor
what does germination require until seedlings can photosynthetically survive
reserve mobilization
what superfamily is the protein of phytochrome part of
same as ethylene and CK but it is nto membrane bound
At a source, sucrose moves into the phloem in the apoplastic pathway by strictly symplastic movement from adjacent mesophyll cells osmosis Tension within sieve tubes produced by sucrose unloading at sink cells secondary active transport into companion cells (using the proton gradient and symport of the sugar)
secondary active transport into companion cells (using the proton gradient and symport of the sugar)
structure of a plant seed
seed coat (alurone) on outside (2n - diploid) - THIS IS MATERNAL embryo (2n - diploid) inside endosperm (3n - triploid) surrounds embryo
what does de-etiolate mean what is a nickname for this what happens in it (3 things)
seedlings growing towards light; light induced preparation for autotrophic growth "greening" what happens is leaves expand, stem elongation occurs, chloroplasts develop thylakoid stacks
Cytokines inhibit ______
senescence
(sink/source) has a lot of diffusion from veins and (sink/source) do not
sink source
source vs sink
source = source of carbs sink = utilization of carbs
what is the vascular core of the root
stele
what open and close to turn on and off transpiration stream, how
stomata in leaves there is a guard cell on the stomata and when water goes into these cells, they open bc of turgor, and when water goes out of these cells they close water follows K+ into and out of the stomata cells
ABA (type of hormone, main purposes, how does it do this)
stress tolerance hormone that shuts down plant growth when environment is not safe negative germination, negative elongation, positive senescence (plant aging) closes stomata during H2O stress
what season do short night plants flower what is the goal of these short night plants
summer (long days) to get more PFR
phloem (what type of movement, are cells alive or dead, what does it transport, what cells help this transport, what direction)
symplastic alive transports sugars and amino acids sieve tubes are the main tubes which have practically no organelles in them of transport but these have companion cells on them which contain organelles to keep the sieve tubes alive can go either direction, just must go from source to sink (one direction at a time)
phloem can do both__________ and __________ transfer from mesophyll cells (where sugar is) depending on if there is a straight connection to sieve or not
symplastic and apoplastic
what effects rate of fluid movement through xylem
temperature and evaporation rate speed up movement vessel width (wider=faster) diameter of put membrane microchannels can be altered by the salt content of sap (more K+ causes peptin to shrink and diameter of pit membrane to get bigger)
xylem water movement moves under ________
tension
xylem sap is under _________ and phloem sap is under __________
tension pressure
germination definition
the development of a plant from a dormant seed
what is solute potential
the higher molarity of a solute in a solution, the more negative the water potential this is because solute bind to water and inhibit its ability to move and do work
if the middle of the plants night/dark is interrupted with light, what happens (for both types of plants)
the long day/short night plants will flower when their night is interupted (as opposed to not flowering after a long night) the short day/long night plants will not flower after a long night if it has been interupted
where does the oxygen produced come from in photosynthesis
the oxygen in water
germination defintion
the sprouting of a seed, spore, or other reproductive body, usually after a period of dormancy
where are apical meristems located
the very tips of roots and shoots
how are plant secondary cell walls different than primary walls
they are much regular arrays of cellulose and their microfibrils are 10x longer than in primary walls (very rigid) specialized polymers also make up these cell walls such as lignin and suburin which are waxes that increase rigidity
properties of classical hormones (size, charge, how do they cross cell membranes)
they are small weak acids and bases they can cross cell membranes in their uncharged form
how do pigments work (structure, what do they do, how do they absorb and transfer this energy, what is this system called)
they have alternating single and double bonds in a porphyrin ring Hydrocarbon tail helps anchor them in thylakoid membrane where they are bound to apoprotein in energy transfer, pigments absorb photons of light which transfer this energy to a center Chl A that is adjacent to the primary electron acceptor of the electron transport system which acts as an electron funnel this pigment has an electron that can get excited this is called the antenna system
DO plants measure the length of sunlight or length of darkness when do long day plants flower
they measure length of darkness long day plants flower when they have a short night)
What is it called when induction of response requires destruction of repressor
this is a derepression event
why does action spectra not drop all the way for green
this is because chlorophyls are the major photosynthetic pigments but carotenoids and phycobilins also contribute as accessory pigments (these are mainly in aquatic plant/algea so they can pick up shorter wavelengths than red as red doesn't make it through water perfectly)
where is light sensed by a plant and what light is most effect what is the hormone that causes this
tip of plant blue light auxin
what is the purpose of stomata
to balance CO2 for photosynthesis and water loss via transpiration
is xylem alive or dead, what type of movement is it, what direction does it go in, what increases flow rate
trachaids and vessel elements die at maturity this allows only apoplastic movement Uniderectional flow upwards flow rate increases when K+ increases
what does phloem do
transports dissolved products of photosynthesis in various directions around the plant
what does xylem do?
transports water from roots to leaves
CAM plants store their C4 in ________ during the day
vaccule
what are the two types of lateral meristems what do they produce
vascular cambium - adds secondary xylem (most of thickening), followed by secondary phloem outside of this Cork cambium - replaces epidermis of the plant with thicker and tougher periderm
what types of tissue can apical meristems make?
vascular, ground, and dermal
According to the pressure flow model for translocation, little ATP expenditure is required. water enters the sieve tube by osmosis. osmosis accomplishes the bulk flow of water and nutrients. sugar is transported out of the sieve tubes near the source area. sugar concentration is highest near the sink area.
water enters the sieve tube by osmosis.
Guitation
when humidity is high, water can be pushed up from the ground as a positive pressure only really works in short plants
H+ symport goes (with/against) concentration gradient, (with/against) electrical gradient, and is what type of active transport
with against (because more + outside of cell which is where it wants to be) secondary active transport
what is another name for secondary xylem
wood
what plants have lateral meristems in addition to apical
woody plants
what makes up vascular tissue
xylem and phloem
do plants have aquaporins
yes
water potential equation
Ψ = Ψs + Ψp
how do plants measure length of day
based off length of night
why does growth occur throughout a plants life
because of indeterminate growth from meristems
what is de-etiolation
becomes green
blind and de-etiolated mutants
blind have lost positive regulators of light response and thus grow tall always de-etiolated mutants have lost negative regulators of light response (or positive regulators of etiolated growth) and expand widly
how ate electron transport systems the same and different in chloroplasts vs mitochondria
both generate proton gradients across the membrane where H+ is higher inside membrane enclosed space both have a PH gradient that drives ATP synthesis There are diff electron carriers and reducing agents (NADPH vs NADH)
where does a plant seed store its reserves
both in the endosperm and embryo
CAM plants have what type of dark reactions (C4 or C3)
both, they separate them temporally
Q: Side shoots on the main stem of a plant are most likely to originate from lateral meristems between the xylem and phloem buds in the axils of the leaves migration of cells from the apical meristem outward bulges from epidermal cells
buds in the axils of the leaves
photosynthesis equation
6CO2 + 6H2O ------> C6H12O6 + 6O2
+ feedback of CK - feedback of CK
+ = CK response (branch growth) - = coating of repressor to regulate homeostasis
what does the C4 cycle require in extra energy total
only requires 2 extra ATP per CO2
what is the output of this cycle
1 G3P molecule leaves (3 carbons and one phosphate) which can help create glucose
A plant cell with turgor pressure of 0.5 MPa and Osmotic potential of -1.0MPa has a water potential of
-0.5
what is the triple response in seeds and when does it occur
1) Apical hook = protects the first leaves (cotelygens) 2) Radical swelling = switches the direction of cellulose growth from horizontal (so plant grows up) to vertical (so plant grows wide) --> stems grow thicker 3) agrotropic = growth against gravity (plant grows up) occurs in the first phase of seedling response when it emerges from sol
steps for how ions go into and out of cell/cell wall
1) H+ pump forces H+ into the cell wall which makes this acidic and sets up concentration gradient 2) cations move from high to low concentration (aka inside the cell) - one example of this is K+ which simply diffuses into cell bc of the gradient (also can cotransport neutral solutes; important for sugar) 3) Anions move down the gradient (follow cations) into the cell via H+ symport
what is the water potential of pure H2O
0
Steps for ethylene signalling
1) ethylene binds to receptor in ER membrane 2) ethylene+receptor blocks activation of repressor (CTR1) 3) permits promotion of ethylene responses by EIN2 and EIN3
what are phloem transportation steps
1) load sugar into phloem (from leaf) 2) xylem water goes into phloem 3) phloem material from source goes to the sink because of a positive pressure 4) sugar goes to the sink (whole point of this) and after, water goes back to xylem
3 major components of chemiosmotic model of polar auxin transport
1) pH gradient across PM: cell acts as an anion trap 2) carrier-mediated auxin uptake: lateral redistribution 3) Basically (at the bottom) localized efflux carriers: confer polarity
Advantages of Z scheme over cyclic photophosphorylation
1) water splitting amplifies pH gradient → drives more ATP synthesis 2) produces NADPH: reducing power required for dark reactions
__________ mole(s) of carbon dioxide must enter the Calvin-Benson cycle for the synthesis of one mole of glucose.
6
how many moles of CO2 are needed toproduce one glucose
6 (duh)
what is the cycle for cyclic light reactions
A photon of light hits photosystem 1, raising the electrons energy this electron then goes through the electron transport chain where H+ is released This H+ helps drive ATP creation using a proton gradient The e- gets recycled back into photosystem 1
what is phototropism
A plant's response to light; growing towards it
How do microfibrils change orientation as cell enlarges
As cells expand there is new microfibrils synthesized onto the cell wall in the perpendicular fashion and the old microfibrils shift to a more vertical orientation Orientation of expansion is maintained
What is the role of auxin in apical dominance
Auxin inhibits buds from starting to grow when put on a plant
Q: Which of the following is NOT part of the acid-growth hypothesis? Auxin stimulates proton pumps in cell membranes Lowered pH results in breakage of cross links between polysaccharides in the cell wall The cell fabric becomes looser (more plastic) due to breakages in cross linked polyssacharides Auxin-activated degradation of transcription repressors stimulates synthesis of new wall components The turgor pressure of the cell exceeds the restraining pressure of the loosened cell wall, and the cell takes up water and elongates
Auxin-activated degradation of transcription repressors stimulates synthesis of new wall components this is long term, not rapid acid growth
auxins produced in ____ and inhibit _____ and promote ______ cytokins produced in ____ and inhibit _____ and promote ______
Auxins produced in shoots and inhibits the shoots and promote roots Cytokinins produced in roots and inhibit the roots and promote shoots
glucose formula
C6H12O6
Which classical hormones (+ BR) activate the repressor
CK
Rubisco has high affinity for _______
CO2
C4 Reaction
CO2 + PEP ----PEP Carboxylase-----> OAA PEP is a 3 Carbon sugar OAA is a 4 carbon sugar
process of GA perception and signaling in aleurone
Ca2+ and cGMP act as secondary messenges Ca2+ promotes secretion GA induces gene expression by destruction of repressor via proteasome which combines with uniquitin to destroy repressors
Q: Phytochrome: Allows plants to determine whether they are shaded by other plants such that they receive light with a higher R/FR ratio than in direct sun Is synthesized in the PFR form and converted to the Pr form by exposure to red light Has some structural and functional similarities to the same protein family as that including ethylene and cytokinin receptors
Has some structural and functional similarities to the same protein family as that including ethylene and cytokinin receptors Allows plants to determine whether they are shaded by other plants such that they receive light with a higher R/FR ratio than in direct sun - LOWER ratio Is synthesized in the PFR form and converted to the Pr form by exposure to red light - Synthesized in PR form
what happens once plant secondary wall is formed
No further expansion possible once you have a secondary wall
what is the repeat unit of the shoot system and what is the space in between this what happens here
Node (where leaf comes out) Internode (space between the nodes)
oxidation vs reduction
Oxidation is loss of electrons (or protons; H+) Reduction is gain of electrons (or protons; H+)
which type of photoreceptor is more stable vs more active
PR is more stable PFR is more active
Q: in C4 photosynthesis... 3PG is the first product of CO2 fixation Rubisco catalyzes the first step in the pathway 4 carbon acids are formed by POP carboxylase in bundle sheath cells Photosynthesis continues at lower CO2 levels than in C3 plants Co2 releases from RuBP and transferred
Photosynthesis continues at lower CO3 levels than in C3 plants 3PG is the first product of CO2 fixation - That's in C3 Rubisco catalyzes the first step in the pathway - That's in C3 4 carbon acids are formed by POP carboxylase in bundle sheath cells - No; its in mesophyl; in bundle sheath 4 carbon is released Co2 releases from RuBP and transferred - No
Plant cells are _________-potent:
Plant cells are totipotent:
plant membrane potentials (what causes resting potential, how long and they last, who do they communicate with)
Pumping H+ out of the cell 2-100x longer than in animals plants communicate to themselves and each other (transmitter T plants to receptor R plants)
What happens in step 2 of calvin cycle (reaction, does it require energy and why)
Reduction of sugars 3PG turnes to G3P (3 carbons sandwiched by 2 phosphates); both have 6 of them it requires energy because reduction requires energy
What happens in step 3 of calvin cycle (reaction, does it require energy, nickname for this step)
Regeneration of RuBP 5 G3Ps turn to 3 RuBPs (5 carbons) This requires ATP from the light reaction
A suspension of algae is incubated in a flask in the presence of both light and CO2. When transferred to the dark, you block the reduction of 3-phosphoglycerate to glyceraldehyde 3-phosphate. When the reduction of 3-phosphoglycerate to glyceraldehyde 3-phosphate is blocked, the concentration of ribulose bisphosphate declines. Why? None of these is correct. 3-phosphoglycerate is converted to glucose. Ribulose bisphosphate is used to synthesize 3-phosphoglycerate. Ribulose bisphosphate is combined with oxygen.
Ribulose bisphosphate is used to synthesize 3-phosphoglycerate.
most abundant protein on planet
RuBP 20-40% of plant protein
reaction of RuBP and CO2
RuBP + CO2 ---Rubisco---> 3PG + glycolate glycolate is toxic
Q: Which of the following statements about plant hormones are true None have any chemical resemblance to any animal hormones Molecular studies have shown that protein families involved in plant signal transduction are unique to this kingdom Signalling always depends on perception at the cell surface, regardless of whether the hormone can cross the cell membrane Secondary messengers involved in plant signal transduction are common to multiple hormones
Secondary messengers involved in plant signal transduction are common to multiple hormones None have any chemical resemblance to any animal hormones - Steroids and peptides look like animal hormones Molecular studies have shown that protein families involved in plant signal transduction are unique to this kingdom - G proteins and protein Kinases are all in animals too Signalling always depends on perception at the cell surface, regardless of whether the hormone can cross the cell membrane - Nope, it can be inside or outside
shoot branches are inhibited by... and promoted by.... root branches are inhibited by ... and promoted by...
Shoot branches are promoted by CK and inhibited by auxin and strigolactones Root branches, called lateral roots, are promoted by auxin and inhibited by CK
All of the following statements about the "Z scheme" of photosynthesis are true EXCEPT: H2O is the ultimate e- donor and NADP+ is the final e- acceptor The energy of the H+ gradient drives synthesis of both ATP and NADPH Photosystem I is able to split water because P700 is a stronger oxidant than P680 Electron transport drives a H+ pump that results in accumulation of H+s inside the thylakoids
The energy of the H+ gradient drives synthesis of both ATP and NADPH Photosystem I is able to split water because P700 is a stronger oxidant than P680
Which of the following processes contributes the most to generating the negative water potential in a leaf? The pressure placed on the leaf by the cuticle (the waxy film that protects the epidermal tissues of a leaf) The movement of water from the veins into the leaf The increased K+ pumped out of guard cells The evaporation of water from mesophyll cells The movement of water into the leaf by root pressure
The evaporation of water from mesophyll cells
In the Darwins' experiment, which part of the seedling was sensitive to light? The sheath just below the tip The entire seedling The extreme tip of the leaf sheath The entire leaf sheath The entire shoot above the roots
The extreme tip of the leaf sheath
protoplast
The living part of a plant cell, which also includes the plasma membrane.
Q: Which of the following statements are NOT true of seeds of flowering plants? They constrain tissues of 3 diff genotypes: embryonic, endosperm, and paternal Their embryos have main tissue types of mature plant Most contain less than 30% at maturity Storage reserves may be present in either embryo or endosperm Only one of the products of double fertilization persists in the next generation
They constrain tissues of 3 diff genotypes: embryonic, endosperm, and paternal Paternal is only polen, maternal is the seed coat
CAM plants what happens, why do they do this at night, what is a name for this
They do C4 at night to build up and store CO2 at night, then use this during the day when they get NADPH from light RXN this decreases water loss by normal stomata cycle tempora; seperation
During the day, do cam plants do anything
They do normal C3
why not always use Z scheme and photosystem II
Z scheme uses more ATP than cyclic
Q: seed development in angiosperms... Results in a structure comprised of only 2 distinct genotypes: embryonic and maternal Depends on ABA produced early in embryoegenesis to induce proper tissue differentiation Usually results in production of a dry, nutrient rich, metabolically inactive structure whose growth can remain arrested for weeks to years Is absolutely required to stimulate growth of surrounding fruit tissue
correct: Usually results in production of a dry, nutrient rich, metabolically inactive structure whose growth can remain arrested for weeks to years Results in a structure comprised of only 2 distinct genotypes: embryonic and maternal - This is missing endosperm Depends on ABA produced early in embryoegenesis to induce proper tissue differentiation - ABA is produced POST embryogenesis Is absolutely required to stimulate growth of surrounding fruit tissue
what of these two light reactions will plants perform if they only need ATP
cyclic
what are the two different ways for light reactions to produce ATP - what type of plants can do each - what does each produce - which is more primitive - where does the e- come from
cyclic and non-cyclic (Z) all plants can do both Cyclic produces ATP Non-Cyclic produces ATP, NADPH, and O2 cyclic is more primitive cyclic: e- keeps getting cycled through acyclic: e- is provided by H2O splitting
what photosystems does cyclic and acyclic use
cyclic: photosystem 1 only acyclic: photosystem 1 and 2
A transfer cell has knobby growths extending into the cell that facilitate movement of minerals from its
cytoplasm into its cell wall.
what does glycolate do
glycolate is toxic it inhibits growth and net loss of CO2
what are the stacks of thalylakoids embedded in the stroma of a chloroplast
grana / granum
Gibberellins were discovered by studying the 'foolish seedling' disease of rice, in which seedlings
grew into tall, spindly plants.
are there any macroscopic pumps in plants to move water up
nope
In vessel elements and sieve tube elements, only sieve tube elements transport substances through the plant. are stacked end-to-end. are dead at maturity. often have companion cells. occur in all plant organs.
often have companion cells.
what parts of a plant are the oldest and which are the youngest
oldest = ground level youngest = tip
