Plants Flashcards
what is gross primary productivity?
photosynthetic CO2 fixation
what is net primary productivity?
GPP- autotrophic respiration
what is autotrophic respiration?
respiration of roots
how much of earths land cleared for agriculture?
40%
When did photosynthesis evolve?
3.5Ba
When was the great oxidation event?
2.5Ba
Whats unique about anoxygenic photosynthesis?
Doesn’t use water as a electron donor (uses sulphide, iron hydrogen instead
What is anoxygenic photosynthesis?
bacterial photosynthesis occurring under anaerobic conditions using photosynthetic ETC (in a non-cyclic mode)
What are the 2 lineages of green plants?
chlorophytes and streptophytes
What did land plants evolve from?
Streptophytes
Are land plants mono or para phyletic?
monophyletic- from streptophytes
What makes up the viridaeplantae?
chlorophytes and streptophytes
what lifecycle did land plants evolve from?
haplodiplonic
what happened 407 Ma?
first plant ecosystems
What is sporopollenin?
protect the pollen grains from external damages such as rain,high temp. Sporopollenin forms the outercovering of the exine & it is the most resistant organic material on the Earth
What is parenchyma?
composed of thin-walled cells and makes up the photosynthetic tissue in leaves, the pulp of fruits, and the endosperm of many seeds.
What is sclerenchyma?
thick, lignified secondary walls, lack cell contents at maturity, and occur throughout all plant tissues adn STRUCTURAL SUPPORT
What is collenchyma?
composed by elongated living cells of uneven primary thick walls It provides support, structure, mechanical strength, and flexibility to the petiole, leaf veins, and stem of young plants, allowing for easy bending without breakage.
What is th eepidermis?
outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant
What are adventitious roots?
form from stem tissues, generally as a result of damage or removal of the primary root system
How are plants highly regenerative in response to sessility?
silent meristems restore growth after damage |+ they can regrow virtually any organ
What are primordia?
organ, structure, or tissue in the earliest stage of development.
what is leaf shape determined by?
serration, lobes and leaflets
are meristems determined by clonal origin or position?
position- meristem. was cut and regrow to look almost identical
What are the 3 types of meristematic tissue?
root apical (RAM), shoot apical(SAM) and cambria
What does pleiotropic mean?
actions other than those for which the agent was specifically developed
What do shuttle proteins do?
transfer phosphate
Why can synthetic hormones stimulate a stronger response?
plants aren’t equipped for catabolism
How are plant hormones used in agriculture?
regeneration of explants- fruit ripening (ethylene) and plant height ( prevent plant lodging)
What are the 2 different types of hormone perception receptors?
membrane associated and soluble
What are the 2 types of cell division?
Periclinal- increase cell layer
Anticlinal- increase number of cells per layer
What establishes polarity and cell elongation?
phosphorylation cascade
What is the hypophysis?
gives rise to some of the root cells.
What determines primordia positioning?
PIN’s sending auxin towards primordium apex
What does the Auxin maxima direct?
cell divisions e.g. emergence of lateral roots
What is vernalisation?
can only flower after a period of cold- down regulated FLC expression
What do giberellins influence?
Long and short day flowering ( needed for long day)
What is a universal transmissible signal molecule to promote flowering?
FLORIGEN
What are leptoids?
bundles of living cells known as leptoids which carry sugars and other nutrients in solution. - like phloem BUT NOT
How are sporangia produced?
by meiosis in sporangia
Is ferm / monilophypte sporophyte diploid or haploid?
diploid- produce spores by meiosis
What is circinate venation?
1 side of leaf grows faster than other, then catches up = unfurls
Why are Azolla watermoss grown in rice paddies?
to fertilise field and they have anabaeba azollae nitrogen fixing cyanobacterium living in cavities
What is sapromyophily a form of?
deceit pollination
What do sapromyophils secrete to attract flies?
volatiles- VERY similar to that of a dead carcass
Whats is unusual about evolution of pitcher plants?
have evolved at least 3 times separately by convergent evolution
Whats in the order Caryophyllales?
cacti, carnations and carnivorous plants
How do ant specific pitcher plants work?
use rain driven torsion to flick antsof stiff nectar secreting lid into pitcher below
WHat are 3 types of pitcher targets?
detritivores, feeder and nesting
How many ATP and NADPH reuqired to fix 3 co2 in calvin-benson-bassham cycle?
9ATP and 6NADPH
WHat is the name for the distinct leaf anatomy of C4 plants?
Kranz or wreath
What is photorespiration?
a respiratory process in many higher plants by which they take up oxygen in the light and give out some carbon dioxide, contrary to the general pattern of photosynthesis.
How is CO2 fixed in CAM plants to be stored for day photosynthesis with stomata closed?
malic acid (decarboxylated in day)
C4 and CAM plants are well adapted to what climate?
hot and relatively water limited- therefore important for future impact of climate change
Why does cell pH drop ovenight in CAM plants?
co2 fixed as malic acid = pH2 can drop to 3
What enzyme does photorespiration use?
rubisco oxygenase
What letters represent the CO2 fixatin enzymes of C4 photosynthesis?
PPDH - PEP regenration, pyruvate, dikinase
What is heliotropism?
response to the direction of the Sun
How does the fig- fig wasp symbiosis work?
female enters ostiole- lays eggs and PURPOSEFULLY pollinates synconium neuter flower - eggs hatch - males mate inside, then dig tunnel out for females who have PURPOSEFULLY collected pollen to take to next
WHat is altruism?
disinterested and selfless concern for the well-being of others.
What is allelopathy?
the chemical inhibition of one plant (or other organism) by another,
Whats the difference between holoparasites and hemparasites?
holoparasites DONT have chlorophyl hemiparasites do (xylem feeders)
What are 2 strategies of parasitic plants?
DRACULA and ROBIN HOOD
What are the 3 categories on plant-plant interaction?
pompetitive, commensal and asymmetric
What is mycoheterotrophy?
ability of plant to live on fungal carbon
What are the advantages of endophytic holoparasites?
evade predation and live in constant environement
What lifehistory is common in monocot lineages?
mycohetrotrophy
What is cavitation of the Xylem?
air seeding
Why is the xylem vunerable to cavitation?
metastable state despite high tensile strength
What do procambrial cells differentiate into?
either xylem or phloem
What is annual NPP a linear function of in drier climates?
precipitation
What does SPAC stand for?
soil-plant-atmosphere continuum
what are 2 equations for water potential?
water potential = pressure potential + solute potential
water potential = turgor pressure- osmostic potential
What are the 2 types of root morphology?
taproot and branching
What is apoplastic movement?
cells walls only
What is symplastic movement?
cell interior and plasmodesmata
What is transcellular movement?
walls + membranes
what allow the low resistance of water movement through membranes?
aquaporins
What are the 2 types of movement through the plant?
radial and longitudinal
What are pit membranes?
primary cell wall without secondary lignification
What was the likely original function of lignification?
water conduction not support
What is the primary mechanism for longdistance transport within the plant?
cohesion-tension theory
what happens to vein density and diameter with increasing leaf area?
density decrease and diameter increase
What is vapour pressure deficit strongly affected by?
leaf boundary layer, - wind and ambient temp
What are stomata influential in? turbulent or still air?
turbulent as smaller boundary ayer
Whats an example of a biochemical resistance to rate of co2 influx and photosynthesis?
calvin cycle
In general is more co2 or water fixed per unit amount of the other?
more co2 per unit water = good water efficiency
Do stomatal guard cell regulate by negative or positive feedback?
NEGATIVE
What is the to hunger or to thirst dilemma?
increasing transpiration decreases photosynthesis and vice versa
In what period did land plants appear and establish themselves?
from early to late devonian
What plant physiological changes occurred during the devonian?
microphylls to macrophylls and big increase in stomatal density
How did low CO2 atm. conc. and transpiration cooling facilitate evolution of macrophyls?
allow cooling and increase SA so tissue doesnt reahc lethal temp.
What is a life-history adaptation to water limited habitats?
deciduousness
How do leafs and stems reduce energy input by irradition?
hairs and cuticular waxes
What is the gynoecium?
innermost whorl of a flower;
are angiosperm gametophytes haploid or diploid?
haploid
What does monoecious mean?
both the male and female reproductive organs in the same individual; hermaphrodite.
What does diecious mean?
having the male and female organs in separate and distinct individuals;
What is the male gametophyte?
pollen grain
What is the megaspore?
egg
What is the microspore?
pollen grain
Where does the pollen tube emerge from on a pollen grain?
colpi
How many cells does the angiosperm female gametophyte (embryo sac) have at maturity?
7 cells
What do the pollen nuclei do during fertilisation once moved down pollen tube?
generative fuses central 2 central nuclei = triploid fusion product and other fuses with haploid egg cell
What happens to the vegetative nucleus?
controls frowth of pollen tube then disintegrates once penerates micropyle
How does pollen discrimination work?
self recognition of pollen tube= reject
+ phenotypic selection of faster growing pollen tube
A gradient of what directs pollen tube towards ovule?
water potential gradient as pollen arrives dehydrated
How does the nuclear endosperm form?
repeated ‘free nuclear’ division of initial endosperm nucleus without cell walls
How does the cellular endosperm form?
repeated normal mitotic divisions w/ cell wall
What is the helobial endosperm?
1st divison with cell wall then 1 half= nuclear and 1 half = cellular
What is a major difference in the prouction of food reserves in gymnosperms and angiosperms?
gymnosperm = BEFORE fertilisation angiosperm= AFTER
