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deck1 Flashcards

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1
Q

what is the name of the oldest plant organism in the world? how old is it? where is it located

A

bristlecone pine, 4,700 years old, rocky mountains

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2
Q

discuss the modular construction of plants

A

the plant is made up of repeating units called modules (node, internode, lateral bud, leaf)

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3
Q

discuss the two different types of organs plants have

A

vegetative organs (used for growth);

roots with root hairs which are used for water uptake

shoots used for growth and contains xylem/phloem

reproductive organs

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4
Q

discuss root structure

A

lateral roots from primary root are used for anchorage

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5
Q

what are the three tissue types in a plant

A

dermal; outer covering of plant

ground; the tissues that sopport the plant, carry out photosynthesis or store photosynthetic product

vascular; movement of water/solutes

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6
Q

discuss the stages plants go through when developing a body plan

A

1) a zygote divides into an apical daughter cell and a basal daughter cell
2) apical daughter cell divides laterally and horizontally into an embryo
3) the 3 tissue systems form by differentiation
4) apical meristem fevelop at bast of embryo; allows for root system to develop

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7
Q

name the shapes a plant embryo goes through

A

octant, globular, heart, torpedo, seedling

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8
Q

name the model plant organism, name which family of plants it belongs to and why it has been selected as a model organism

A 
Arabidopsis thaliana;
cabbage family (brassicaceae)
short life cycle, small genome, produces lots of seeds
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9
Q

state what experiment have been done on Arabidopsis thaliana to study the sequence of events in embryogenesis

A

mutation of genes to establish what phenotype characteristic the mutation related too

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10
Q

how do plants grow

A

1) cell elongation; uptake water into vacuole and loosen cell walls by expansin action
2) cell division from meristems

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11
Q

discuss location of meristems

A

tip of roots, shoots and leaves used for growth of shoot root and leaves

auxillary meristems at nodes used to produce lateral buds

cylinderical lateral meristems in stem/roots which allow for secondary grwoth (thickening)

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12
Q

discuss the root cap and quiescent centre

A

the root cap is an area without meristems which exists to protect the meristems when roots are penetrating through soil. it has gravity perception

the quiescent centre is of very slow cell division which produces tissues needed for the root cap to elongate

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13
Q

which plant hormones can be related to growth

A

the auxins and cytokinins cause apical dominance which leads to upward growth

the gibberelins cause elongation of internodes

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14
Q

what are the features of a rosette, and why is a rosette like this, what types of rosette are there

A

a plant that is very low to the ground with radial symmetry

internodes fail to grow

spiral phylotaxy
oppositr phyllotaxy

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15
Q

what does phyllotaxy mean

A

arrangemment of leaves arounf the stem

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16
Q

how can you measure plant growth and what are the equations for this

A

RGR=LAR x NAR

relative growth rate, leaf area ratio, net assimilation rate

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17
Q

what is the equation to measure leaf area ratio

A

LAR= SLA x LMR

specific leaf area, leaf mass ratio

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18
Q

whare some factors that influence plant growth and therefore explain why plants grow at ifferent rates

A

rate of photosynthesis
water availability
nutrient availability
genetic factors

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19
Q

what causes differentiation into specialised cells

A

internal signals like hromones as well as external signals like light induce gene expression changes

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20
Q

if all cells have the same genetic mateiral then how do cells differentiate into different cells

A

different sets of genes are expressed

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21
Q

discuss different plant epridermal cells and their functions

A

pavement cells; morphologically unspecialised cells which place out stomata and have structural function

stomata; regulate water and gas exchange

trichomes; produce chemcials and therefore offer protection against predators

root hair cells; cells with increased surface area which are specialised for nutrient uptake

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22
Q

what is the function of cone shaped cells on the epidermis

A

enhance heat and light capture

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23
Q

which genes and hormone regulate senescence. which cell process is key

A

senescence associated genes (SAG’s)
ethylene
apoptosis

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24
Q

what is the function of the flower has a whole

A

provide a mechanism of sperm and egg union

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25
Q

what are the two names for fertilisation in plants

A

outcrossing

selfing

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26
Q

discuss the anatomy of a flower

A

stamen (male reproductive organs) a filament sopports an anther which produces pollen (contians sperm)

carpel (female reproductive organs); a sticky stigma traps pollen via its hairs
an ovary exists below the stigma which produces eggs; a style connects the two structures

petals; brightly coloured to attract pollinator animals

sepals; leafy parts that wrap around flower bud and protect it during development

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27
Q

denine pollination

A

movement of pollen (containing sperm) from the anther to the stigma

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28
Q

what percentage of plants are flowering plants

A

60%

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29
Q

what initiates flowering

A

a developmental switch causes a shift from development of vegetative organs to reproductive organs;
vegetative meristems stop producing leaves and reproductive meristems start divising to produce flower parts

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30
Q

what can signal for flowering to begin

A

vernalisation (coldness), day length (photoperiod) or developmental age

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31
Q

what plant was used to investigate photoperiod? what were the results

A

a mutant tobacco (maryland mammoth) and soy beans

even if flowers are sewn over a 3 month period they all still flower within a 3 week period in september

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32
Q

compare short day, long night plants against long day, short night plants,against day neutral plants

A

short night;
hanbane
only flower if day length is above 14 hours
flower in spring/early summer

long night;
maryland mammoth
day length has to be shorter than 14 hours
flowering ococurs in late late summer/autumn

day neutral;
maize, tomato
flowering is regulated by other factors apart from dya length, such as temperature and age

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33
Q

whis is key in photoperiodism initiating flowering, day length or night length

A

night length

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34
Q

what percieves photoperiod, meristems of leaves

A

leaves, masking leaves causes flowering changes whereas masking meristems does nothing

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35
Q

what is the molecule that absorbs red and far red light, how does it initiate flowering

A

phytochtome absorbs red/far red light via its chromaphore
the molecule undergoes a confirmational shape change which impacts gene expression by interacting with transcription factors

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36
Q

red light and far red light exist, which causes flowering and which causes dormancy

A

red light causes flowering

far red light causes dormancy

these different lights reverse the effectsof eachother; the last wavelength the plant is exposed to is the one that has its effect

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37
Q

discuss the GNR relating to photoperiod induced flowering

A

1) when the correct photoperiod is present, the CONSTANS protein is stabilised
2) transcription of florigen ococurs (flowering locus T)
3) florigen enters phloem, travels to leaf and combines with flowering locus D; trnascription of APTELA1
4) APTELA1 initates flowering by commiting meristems to produce floral genes not vegatatitve genes

organ identiy genes control development of floral parts

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38
Q

where is florigen synthesised

A

phloem companion cells before being translocated

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39
Q

what type of gene if FLOWERING LOCUS T

What type of gene is APTELA1

A

FT is a flowering time genes; determines when flowering is initiated

APTELA1 is a floral identity gene

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40
Q

what is the ABC model of plan development

A

the idea that plants have 4 whorls (parts); sepals, petals, stemens, carpels and each whorl requires a different set of genes to be expressed for normal development.

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41
Q

how has the ABC model of the 4 whorls been investigated, what were the results

A

using mutants; if the a gene set is mutated then all the neccassary flower parts dont develop

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42
Q

which gene sets are antagonistic (prevent expression of eachother)

A

gene set A (APTALA1, APTALA2) and set C (AGAMOUS)

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43
Q

draw the table of gene sets and which whorls require them

A

check in notes

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44
Q

more complicated way of saying 24 hours and how this related to plants

A

circadian time cycle

leaves and flowers move in a 24 hour cycle and gene expression changes throughout the course of the day

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45
Q

why is plants having the ability to measure time an advanatge

A

it means changes in environment can be anticipated

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46
Q

when does a stem growth occour

A

night time

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47
Q

is the circadian rhythm effected by temperature, does the rhythm persist in the absence of external cues, can the rhythm be reset by external cues

A

no

yes

yes

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48
Q

what piece of equipment is used to measure leaf movements

A

a rotating drum

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49
Q

what happens when bean plants are placed in constant light

A

they operate of a 25.7 hour cycle. amplitude of movements decreases

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50
Q

what picks up light signal

what does this molecule reset which untilamtely causes differing gene expression

A

phytochrome

resets central oscillator

CCA1 (an MYB family gene) is expressed early in the day which blocks expression of TOC1 gene.

at night TOC1 gene (MYB gene) is expressed which blocks expression of the CCA1 gene

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51
Q

discuss concentrations of Pr and Pfr over the course of the day/night

A

Pfr is converted to Pr over the course of the day, when is converted back to Pfr overnight

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52
Q

what are the two carbodydrate molecule in plants and where are they synthesised

A

starch; synthesised in chloroplast

sucrose; synthesises in cytosol

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53
Q

do most plants store starch or sucrose in the roots, what an example of a plant that doesnt

A

most store starch

beet stores sucrose

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54
Q

what molecule are carbodydrates moved as and why

A

starch; it is used for transport because its a stable non reducing sugar

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55
Q

what is evidence for the phloem being used to transport of assimilates

A

dridling (ring barking) blocks translocation

radioactive marked sucrose has been shown to be moed into the phloe

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56
Q

what species of plant has mainly amino acids in its phloem, compared to most plants (mainly sucrose in the phloen)

A

cubitacaea

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57
Q

discuss the anatomy of the phloem system

A

sieve tubes; nuclues lacking, organelle lacking tubes

sieve plates exist between sieve tube cells, they have holes in them to allow passage of assimilates

companion cells; interacts with sieve tube element and has a role with loading/unlaoding of assimilates

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58
Q

what is the bundle sheath

A

a layer of cells sorrounding the vascular bundle

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59
Q

what is the pressure flow model

A

a model which explains transport of assimilatesin the phloem;
when assimilates are loaded into the sieve tube, the water potential to decrease, so water moves by osmosis from xylem into this part of the phloem; hydrostatic increases and forces sap through sieve plates towords sink.

at sink the assimilates are unloaded, which increases water potantiol so water moves back into the xylem

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60
Q

is there a low or high energy requirement for translocation

A

low

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61
Q

what are the two methods of laoding assimilates into the phloem

A

symplastic; through plasmodesmata. requires a high concentration gradient

apoplastic; assimialtes are moved across cell membranes into apoplast. this requires energy

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62
Q

what is the polymer trapping model

A

the idea that the cells between the vascular bundle and the bundle sheath convert sucrose into raffinose (trisaccaride) and stachyose (tetrasaccaride) before the molecules enter the sieve tube

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63
Q

what are the 3 routes of unloading from the phloem; which plants use each method

A

symplatic; sucrose moves into cells via plasmodesmata;
leaves/root tips

apoplastic; sucrose is unloaded into apoplast before active transport into cells
sugar cane

apoplast; sucrose is unloaded into the apoplast before being hydrolysed into glucose and fructose which is then actively transported into cell
legumes

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64
Q

how is it determined which sink the assimilates go to

A 
sink strength (sink size x sink activity)
proximity of sink to source is important as well as the vascular connections to different sinks
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65
Q

discuss stomata physiology

A

2 guard cells exist which have thickened inner walls.

stomatal pore between guard cells

guard cells are sorrounded by subsiduary cells

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66
Q

discuss the three different ways stomata can be arranged

A

randomly

clustered

in linear rows

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67
Q

whats the equation for stomatal density

A

number of stomata/leaf area

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68
Q

what is the stomatal index

A

the number of stomata in relation to the number of epidermal cells

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69
Q

which gene controls stomatal pattrerning

A

ERECTA (ER)

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70
Q

discuss how monocot and dicot ( 2 types) differ in where stomata are located

A

monocot; 50% lower

woody dicot; 100% lower

non woody dicot; 60% lower

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71
Q

what is the name for a non woody dicot

A

herbaceous

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72
Q

discuss the mechanism by which stomata open

A

1) H+ expelled from guard cells and create an electrochemical gradient (ATPas activity)
2) K+, Cl- and H+ enter guard cells from subsiduary cells, and are transported to the vacuole reducing water potentiol
3) water enters which causes cells to swell

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73
Q

what is the mechanism by which stomata close

A

1) Ca+ enters guard cells
2) K+ and Cl- channels open causing these molecules to leave guard cell down thier concentration gradient
3) what potentiol in vacuole increases so water leaves

Ca+ also inhibits the action of the H+ ATPase

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74
Q

whats an osmoticum

A

a molecule that helps maintain osmotic pressure

75
Q

when K+, H+ and Cl- enter vacuole, how is the postive charge balanced

A

starch is broken fown into malate which is negatively charged

76
Q

what are protoplasts and how have they been used to investigate this mechanism

A

free cells that havehad their cell wall degraded.

they have been used for patch clamping (using an electrode to measure ion movement

77
Q

name an inhibitor and an activator drugs of the H+ ATPase

A

fusicoccin stimualtes the enzyme

CCP and vanadate inhibt the enzyme

78
Q

how is the H+ATPase activated (and therefore stomatal opening activated)

A

xanophylls percieve blue light and activate the enzyme

79
Q

why do CAM plants not open their stomata during the day

A

their xanophylls respond differently to blue light and dont initate H+ ATPase activity

80
Q

discuss how co2 concentration and water vapour loss relate to stomata

A

when the carbon dioide concentration in a plant is high, the stomata are closed as no co2 uptake is required

loss of water vapour causes stomatal closure

81
Q

discuss the 2 different types of stomatal closure in relation to loss of water vapour

A

hydropassive; water loss causes stomatal cell shrinkage; direct closure

hydroactive; loss of water vapour causing a signalling process to occour leading to Ca+ influx which causes stomatal closure

82
Q

what is the mechanism by which ABA causes stomatal closure

A

ABA is transported from the roots to the leaves where it causes causes the calcium channels to open and calcium to enter and causea cascade of effects leading to stomatal closure

83
Q

discuss the boundry layer and wind speed in relation to water loss

A

the boudry layer is the layer of air around the leaves. if wind speed is high then water vapour is moved out of the boundry layer and water loss occours more

84
Q

what is the water use efficiency and which plant type has the highest value

A

molecules of co2 taken in for every water molecule lost

CAM plants, then C4 plants then C3 plants

85
Q

what is the mid day depression

A

when c3 and c4 plants close their stomata at midday for a short period of time to avoid water loss at the hottest time of day

86
Q

discuss the advantages of CAM plants opening the stomata at night in terms of stomatal resistance

A

the stomata can be closed during the day therefore plants have high stomatal resistance to water loss

87
Q

what % of crops loss does abiotic stress cause

A

40%

88
Q

what are the 4 different types of responses plants have to stresses

A

localised; occour in a specific part of the organism

symstematic; occour throughout the whole organism

short term; ococur within minutes
long term; takes days/weeks to occour

89
Q

plants can either _______ or ______ to plant stresses

A

resist; change physiology and metabolism to avoid the effect of the stress

avoid; perceive stress and dotn respond. the metabolic cost of responding isint worth it

90
Q

why does water loss effect plants

A

1) water loss means increase in concentration of solutes, which may alter pH etc and effect enzymes
2) plants have to close their stomata to stop water loss; reduced carbon dioxide uptake means reduced photosynthesis and therefore growth
3) ageing is accelerated
4) rehydration makes membranes porous

91
Q

discuss the 3 biochemical responses to water loss

A

1) production of compatible solutes which increase osmotic force and drive water into cells
2) produce hydrophillic proteins like LEA which retain water and release it slowly
3) induction of CAM; metabolism

92
Q

discuss anatomical responses to water loss

A

1) formation of an enhanced root system that penetrates deeper soils
2) ensure that when new leaves are formed they have a lower stomatal density and more wax to icnrease stomatal resistance
3) existing leaves are stopped from expanding, and have their stomata shut
4) become succulent; produce water storage tissues

93
Q

state 4 ways that plants that live in water scarce environments are adapted to lack of water

A

1) extended root systems
2) reduce metabolism
3) short life cycle; germination, flowering and setting seeds all occours in short wet season
4) oppertune leaf production; only producign leaves when water is available

94
Q

discuss water excess as a stressor

state 3 adaptions to this environment

A

roots submerged in water is a problem because it means no oxygen or nutrient uptake

1) production of alcohol fermention enzyme (ATP can be produced without oxygen)
2) production of pneumatophores; root like extensions in air for oxygen uptake
3) aerenchyma has evolved; parenchymic cells (ground tissue) form air vessels to transport oxygen from shoots to roots

95
Q

where are aerenchyma located

A

they surround the vascular system

96
Q

what is salt stress most commonly caused by

A

high cocnentrations of ions (Na2+ and Ca2+ in particular)

97
Q

discuss locations where salt stress happens

A

lakes where evaporation exceeds precipitation

irrigated soils

groundwtater when the area recieves little precipitation

coastal marshes (wetlands)

98
Q

discuss the two ways salt stress changes soil, which then has negative impacts on plants

A

water cant move freely in salt stressed soil (its been made more porous/aerated which means less hydraulic action)

salt stressed soil has a lower water potentiol than normal soil; less uptake of water occours

99
Q

what effects does salt stressed soils/water have on plants

A

ionic imbalances between different cell compartments

enzyme inhibition occours leading to cell death

reduced photosynthesis and therefore reduced grwoth

100
Q

discuss the three plant types in relation to salt environments and an example of each

A

glycophytes;
get salt stressed at high salt concentrations
can survive in soil with max 100mM NaCl
most plants; rice

salt tolerant non-halophytes;
plants that can tolerate salt concentrations of up to 200 mM NaCl
tomato

halophytes;
plants that are adapted to salt concentrations of 500mM NaCL and show increased growth at these conditions
ice plant, salt cress

101
Q

what are some mechanisms plants use to reduce salt stress

A

produce compatible solutes to drive water into cells so ions are less concentrated

high selectivity of ion uptake

presence of ion transporters in cells allows for ions to be sequestered into vacuoles where they cant effect metabolism

rootss extrude toxic ions that have been taken up

102
Q

name some compatible solutes

discuss which charge is possessed by compatible solutes

A

amino acids like prolin, betaine

neutral charge

103
Q

discuss how some plants are adapted to salt stress

A

high quantities of compatible solutes

presence of bladder cells; cells with large vacuoles that can sequestrate high large quantities of salt

presence of glands that can exrete salt to the surface

104
Q

what is a plant type that can extrude salt to the surface

A

mangroves

105
Q

what is usually the optimum temperature for plant growth

A

20-30 degrees centigrade

106
Q

discuss the effects high temperatures have on plants,

responses plants can have to high temperatures

discuss adaptions plants have to high temperatures

A

effects include

1) increased evapotranspiration which causes plant wilting
2) reduced photosynthesis due to enzyme inhibition/denaturing
3) increased respiration and therefore photorespiration
4) increased fluidity of the thylakoid membrane

responses include;

1) stomatal closure to reduce water loss
2) increased expressionof heat shock proteins (HSP’s) which stabilise enzymes in high heat
3) increased synthesis of saturated fatty acids for the phosopholipid bilayer to reduce fluidity

adaptions to high heat conditions are possessed by thermophiles;

1) rolling of leaves which reduces transpirational losses of water
2) thin leaves which are best for losing heat
3) presence of a thick waxy cuticle which reflects light

107
Q

what temperatures can agave and cactus survive in

A

70 degrees centigrade

108
Q

discuss effects that low temperature has on plants, responses plants can have and adaptions plants have

A

effects can include;

1) reduced enzyme activity which leads to reduced metbaolism
2) decreased membrane fluidiy due to crystalisation
3) reduced water availability as water turns to ie
4) reduced photosynthesis

responses to low rtemperature conditions incolve;

1) increases synthesis of unsaturated fatty acids for the phospholipid bilayer to increases fluidity
2) increased synthesis of compatible solutes which prevent water from freezing
3) increased ion uptake from soils which decreases the freezing point

adaptions to low temperature conditions involve;

1) accumualtion of LEA proteins to retain water
2) induction of dormancy
3) starch breakdown into soluble sugars

109
Q

what is a plant that can survive in temperatures as low as -70 degrees

A

laryx dahurica

110
Q

name some pollutants in the air

A 
sulphur oxides
carbon oxides
nitrogen oxides
peroacetyl nitrate (PAN)
heavy metals
111
Q

discuss effects on plants that air pollution has and responses

A

air pollution causes plants to close their stomata, habe lesions (damaged tissue), necrosis (cell death), bleaching (loss of chlorophyll)

responses to air pollution stress include closure of stomata, production of enzymes like peroxidases which detoxify cells
and production of ROS-scavenging compounds

112
Q

what is a mechanism by which air pollutants cause damage within plants

A

air pollutants produce Reactive Oxygen specues (ROS) which cause a cascade of reactions within cells and damage membranes etc

113
Q

what is one example of an ROS-scavenging compound

A

absorbic acid

glutathionine

114
Q

heavy metals can pollute soils, name some heavy metals

A

lead, nickel, cyanide, mercuary

115
Q

what are two characterisitcs of plants that thrive in heavy metal polluted soil

A

those that can selectively uptake nutrients and leave behind heavy metal elements and those who can sequestrate heavy metals

116
Q

name some plant methods of sequestration

A

combining metal ions with amino acids containing sulphur

combining heavy metals with acids like malate
production of phytochelatins which are sulphur containing polypeptides which bind to metal and move into the vacuole where the heavy metals cant be damaging

117
Q

deifne phytoremediation

A

growing specific plants of heavy metal polluted soils that will upake and sequestrate the heavy metal ions

118
Q

define phytomining

A

growing plants that hyperaccumulate heavy metals, and then harvesting the metals from the plants

119
Q

discuss the 4 receptors that exist

A

1) cytoplasmic receptors (CR) which ligands bind to after diffusing across plasma membrane. binding causes a conformational change in receptor causing a chaperone to disccoiate allowing the receptor to move into the nucleus
2) ion channel receptors that that open due to chemical signals and physical signals
3) G protein coupled reactions (GPCR); a ligand binds to the ectracellular N terminal causing the C terminal in the cytoplasm to cause a signalling cascade via secondary messengers like cAMP.
4) receptor like kinases (RLK) a ligand binds to the extracellular N terminal which causes a conformational shape change of the transmembrane domain causing a protein kinase at the C terminal to be activated which causes a cascade fo effects via phosphorylation

120
Q

which receptor is common in animals and why is common in plant cells

A

animal cells tend to have G protein coupled receptors where as plants have Receptor like kinases

121
Q

where is calcium concentration high

A

extracellularly,
within compartments in the cell like the ER, vacuole
NOT in the cytoplasm

122
Q

what type of moelcule is cAMP and how is it is produced

A

cAMP is a cyclic nucleotide. G proteins activate Adenylate cyclase to convert ATP to cAMP

123
Q

name two groups of proteins cAMP activates

A

ion channels

protein kinases

124
Q

discuss NO as a secondary messenger

A

NO synthase is activated by calcium and convertes arginine to NO, which goes on to cactivate enzymes that convert GTP to cGMP

125
Q

discuss the phosphoinositide pathway

A

A G protein receptor is activated, so that one of its subunits dissociates and activates the phospholipase C enzyme which releases IP3

126
Q

discuss differences betwen plant animal hormones

A

plant hormones are sometimes called plant growth regilators

plant hormones are produced at specifiec sites and may act systematically rather than at specific areas

127
Q

are hormones present at high or low concentrations

A

high

128
Q

discuss the effects auxins have

A

apicial dominance; the auxins are only transported to the apical bud
cell elongation by activating protein pumps that move protons into the cell wall and decrease pH which activates expansins to loosen cell wall

degrade TF's which cause nutrients to be moved from old leaves to new leaves
cause gravotropism (downward root growth)
129
Q

how are auxins synthesised

A

the trypophan aminoacid is transaminated into IPA, which is decarboxylated into IAALD, which is oxiadted into IAA

130
Q

discuss how auxins mov ein plants

A

only only move in polar way (downwards). they are transported out of cells via efflux transporters called PIN proteins

131
Q

discuss applications of auxins

A

when used in high concentrations they have a herbicide effect
at low concentrations they have anti-senescence effect and can be used to stop fruit drop

132
Q

where are high concentrations of auxins found

A

meristem regions of growing organs

133
Q

discuss the forms of auxin

A

it exists in a free form and a conjugate form (attahced to a guar or protein). this storage conjugate form can be hydrolysed to release active auxin

134
Q

how are auxins degraded

A

oxidation by peroxides
UV light
performing oxidative decarboxylation of IAA

135
Q

whjat effect do gibberelins have

A

cause stem elongation through cell division

stimualte flowering in response to long days

break seed dormancy

stop senescence

136
Q

how are auxins synthesised

A

acetyl CoA is converted to gibberelins via the mevalonic acid pathway.
most are inactivated upon synthesis, and are then reactivated when they have been transported to where they need to be

137
Q

how many carbons do gibberelin molecules have

A

19/20

138
Q

how are gibberelins transported

A

in both xylem and phloem

can be transported in both directions unlike auxins

139
Q

discuss applications of gibberelins

A

produce seedless fruit which are much larger than they normally would be

increase crop yields due to elongated internodes

make plants bolt (grow quickly and set seeds)

140
Q

what is the effect of cytokinins

A

work alongside auxins during morphogenesis of tissues
cell elongation
delayed senescence

141
Q

discuss the effects abscisic acid has on plants

A

induces seed dormancy

induces stomata closure

promotes abcission and senescence

142
Q

discuss the applications of abscisic acid

A

it can be applied to plants to prevent transpiration/water loss

143
Q

discuss the effects ethylene has

A

induces fruit maturating and ripening

causes senescence

144
Q

how is ethylene transported

A

in the air from plant to plant, and then in the xylem and phloem when its inside plants

145
Q

how is ethylene synthesised

A

all organs are capable of producing it. the methionine amino acid is used as a substrate

146
Q

discuss ethylene applications

A

can be used to induce ripening

147
Q

discuss the effects of jasmonic acid

A

used for communication within a plant and between plants

defence against predators; activation of inhibitors which poison animals

148
Q

how is jasmonate synthesised

A

whena leaf is damaged the phospholipid membrane breaks down into molecules that are converted to jasmonates, which enter nucleus and change transcription

149
Q

discuss the long distance signalling pathway involving ABA

A

roots detect water stress and produce Abscisic acid which travels in the xylem to leaves and induces stomata closure

150
Q

discuss the long distance pathway involving auxins

A

auxins are produced at the top of the plant and then transported via the stele (central root) where it has gravotropism effects

151
Q

discuss long distance signalling of nitrogen content

A

plant shoot measures nitrogen content and signals for changes in amount of nitrogen transporters in the roots via altered expression

152
Q

discuss long distance signalling for hypoxic soils

A

when the roots are flooded, ethylene is used to signal this condition and oxygen is transported via aerenchyma to the roots

153
Q

how is oxygen concentration detected

A

indirectly through changes in pH, ATP concentration. low oxygen concentration activates ethanol fermention, which doesnt require oxygen

154
Q

which partof the plant signals the carbon dioxide concentrations

A

mature leaves

155
Q

how does the plant respond to increased atmospheric co2 concentrations

A

new leaves have lower stomatal density

156
Q

in terms of plant to plant communication, what do jasmonic acid and ethylene signal for

A

ethylene signals pathogenic attacks and environmental stresses

jasmonic acid signals for wouldings, for example from grazers

157
Q

what chemical to plants release into the soil in order to be competitive

A

sequiteropenoids are released into the soil and inhibit germination of other plants

158
Q

what is a hydroponic culture

A

a water environment with nutrient concentrations defined

159
Q

another name for a nutreint solution

A

hoglands solution

160
Q

what are the macronutrients

A

nitrogen, potassium, calcium, phosphorus, sulphur, magnesium, silicon

161
Q

what are the micronutrients

A

calcium, magnesium, zinc, copper, iron, nickle

162
Q

what are three main elements in plants

A

carbon 45%
oxygen 45%
hydrogen 6%

163
Q

what charge do soil particles have and what charge do nutrients have

A

soil particles are negatively charged

nutrients are positively charged

164
Q

what is a colloid’s

A

an insoluble substance dispersed/suspended through another substance. mineral nutrients form micelles

165
Q

what effects weather or nor mineral nutrients are taken up from soil

A

the pH of the soil effects weather or not nutrients are uptaken. all nutrients have an optimum pH for uptake (slightly acidic)

166
Q

what are depletion zones and how to plant respond to them

A

zones of low nutrient concentration that form near to the roots. the roots detect this zone and grow towords areas of high nutrient concentration

167
Q

define rhizosphere

A

the beneficial interaction between plant roots and microbes to maximise nutrient and water uptake

168
Q

what are the differences between mutalism and symbiois

A

mutualism benefits both partners whereas symbiois benefits 1/both partners

169
Q

what is the name of the association between plant roots and fungi, discuss this associaiton

A

mycorrhizae; fungi obtains carbohydrates and plant recieves minerals. the fungis hyphae grow around the root and are known as a fungal sheath. mycelium extends into roots and either penetrates cells or forms a network between cells

170
Q

what is the collective name for a fungi’s hyphae

A

mycelium

171
Q

what nutrients does the plant gain from the mycorrhae interaction

A

nitrrogen, potassium and phosphorus. mainly phosphorus

172
Q

what percentage of plants have mycorrhizae interactions

A

80%

173
Q

when are mycorrhizae interactions missing

A

in dry, flooded, nutrient poor or saline soils

174
Q

discuss the difference betwen ectomycorrhizae, endomycorrhizae and ectendomycorrhizae

A

ectomycorrhizae; an external sheath of mycelium exists perhaps with hyphae between cells but not penetration into cells

endomycorrhizae; there is no external sheath of mycelium but there is a well developed hartig net and much penetration of cells

ectendomycorrhizar; a well developed hartig net is present with possible penetration of cells and minimal hartig net

175
Q

define hartig net

A

the hyphae network between plant root cells

176
Q

what is the name of the bacteria plants form an association with

A

rhizobium

177
Q

which plant group forms the rhizobium interaction

A

legumes

178
Q

how do plant cells become infected with rhizobium bacteira

A

the plant releases flavanoid compounds into the soil which is detected by bacteria which produce nodulation factors; this causes root hair cells to grow in a curled wat around the bacteira

179
Q

how do rhizobium fix atmospheric nitrogen

A

they have the ferredoxin-nitrogenase complex (N2>NH3). ammonia is toxic so plant processes it into glutamate

180
Q

name a third plant-microbe interaction

A

fern-blue-green cyanobacteria
cyanobacteria enter growing shoots and fix nitrogen in specialised cells called heterocysts
south asian rice fields

181
Q

discuss similarites between plants and algae

A

both have a cellulose cell wall, similar enzymes, same type of rRNA, use of chlorophyll a and b for photosynthesis and form a cell plate during cell division

182
Q

what is the name of molecules needed by land plants for protection against UV light

A

carotenoids

183
Q

how many plant species exist

A

450,000

184
Q

how many species of angiosperm are ther

A

260,000

plant biology 2 (1 decks)

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