mm- plants and enviroment Flashcards
Which of the following is not a barrier to plant reproduction? (Pre and post fertilisation)
A Asynchrony of flowering
B Lower mineral content of seed
C Floral morphology/ self-incompatibility
D Hybrid weakness
E Sterility
OTPION B as that doesn’t affect reproduction
• Pre- fertilisation
Asynchrony of flowering and Floral morphology/self-incompatibility
• Post- fertilisation
Hybrid weakness and Sterility
How does Dioecy separate the sexes of flower? E.g. humans or squash plant
One plant has only stamens (is male) and a different plant has only pistils (is female)
What type of mycorrhizal association involves the hyphae penetrating the root epidermis and colonizing the cortex of the plant?
ectomycorrhyzal
endomycorrhyzal
arbuscular
Arbuscular . Note that the cell membrane INVAGINATES-never broken
» arbuscular is one of 4 types of endomycohyzal
ectomycoorhizal - hartig net froms between epidermal and cortical cells / no penetration
What is photoinhibition?
The inhibition of photosynthesis when when the rate of damage of the photosystems is greater than the rate of repair
when there is excess light
What is the mechanism that leads to stomatal opening? sodium pumps calcium pumps hydrogen pumps potassium pumps chloride pumps
K+ ions are pumped into the guard cells and water enters the guard cells by osmosis
cells become TURGID so guard OPENS stomata
solvent follows solute
Plants have Nodulation (nod) genes. True or false?
POOP
false, they have NODULIN genes. Rhibozium has the nod genes that cause the root hair to curl around the rhizobium.
this allows for mycorrhizal association
During water stress/drought what hormone increases in plants?
Abscisic Acid (ABA)
it inhibits K+/water influx so guard cells are FLACCID and stomata are closed
> plant can conserve water
Where is ABA produced? plant leaf plant stem plant root plant flowers
in the plant roots. ABA is transported to the leaves through the transpiration stream.
function of legohaemogoblin?
much higher affinity for oxygen.
It allows enough oxygen for respiration but keeps free oxygen levels low fo optiumum enzyme activity in ROOT NODULES
Why do plants form mycorrhizal associations?
It extends the area they can obtain their nutrients from, past the depletion zone
describe the endosperm of plants (gentics)
triploid structure - 2 polar nuclei and spem cells)
endosperm provides nutrition to embryo
where does pollen land
anther
stigma
pollen lands on the stigma = the top of the ovary
what is epihydrophiliy
what is hypohydrophily
method of ABIOTIC POLLINATION
epi- pollen floats on water
hypo - pollen is carried by water stream
why is water pollination risky/dangerou?
pollen is quite a dehydrates structure
decribe the shape changes that occur in floral embryology
zygote divides asymmertrically to produce a proembryo and a cotelydon `
circle -> heart -> torpedo -> cotelydon
which statement is flase?
endosperm is triploid
femail gametophyte contains 8 nuclei
plant haploid cells do not undergo mitosis
plant haploid cells DO do mitosis
which is false
pollen tubes grow down the style (fertilisation)
plant embryos grow from heart to torpedo shape
all plants have 2 cotelydons
OPTION C
some plants have 1 cotelydon = monocot!!
synergid cells - what do?
they burst and allow pollen tube to enter ovule and release sperm
which is correct
A stigma produces the pollen
B plant beomces heart shape before it germinates
C cotelydons take up most space in a dicot seed
D endosperm takes up most space in a dicot seed
OPTION C
a- anther produces the pollen
b- embyro becomes heart shape
d- endosperm takes up most space in moncot
why is water seed dispersalrisky/dangerous
seeds are also dehydrated strcutures so will germinate if placed in water
> coconut segde seed, spongy/trapped air to float
what hormone regualtes seed germaition and how doews it do this? abscisic acid (ABA) IAA synergid gibberalic acid (GA) auxin
gibberilic acid!
it stimulates the aleurone layer of endosperm to produce sugar = energy souce for embryo
what drives above gorund growth hypocotyl cotelydon shoot apical meristem radicle
SAM!
a- stem
b- leaves
d- roots
how does protoygyny and protoandry comapre
protogyny = stigma matures before anther protoandry = anther mature before stigma
exammple of temporal speatrion to prevent self fertilisation and used by HERKOGAMY
how does ddecy, monodecy and herkogamy compare
diodecy = different plants, different genders (human, squash flowers) monoecy = same plant but each flower is different herkogamy = both male and female within
why is nitrogon fixation anaerobic?
nitrogenase activity INACTIVATED by oxygen so nitrogen fication occurs in anaerobic conditions
acclimiation vs adaptation
acclimatize is short termadaptation due to envrionemntal pressure
adaptation is long term, affecting evolutionary process
what happens in high intenstiy light
xanthophyll to zeanthin or
zeaxanthin to xanthopyll
x- > Z as zeaxanthin is protective by dissipating the excess sunlight
what long term adatptations to platns have in low light intensit thicker leaves/cuticle red underside hairs on leaves more rubisco thinner leaves/cuticle
thinner leaves to get maximum light absoprtion/large S.A
more chlorophyll
red underside which reflect light back to the leaf!
nutrient uptake by elongated roots in the soil describes bulk flow interception diffusion osmosis
INTERCEPTION
bulk flow- nutrient dissolved in water and pulled up by transpiration
