25: plant form & function II - seed + root development Flashcards
where are the SAM and RAM established?
in the embryo
the embryo, endosperm, and seed coat are all diploid except for?
endosperm! it’s triploid
the structure of a mature eudicot seed?
- 2 thick cotyledons
- seed coat
- radicle
- embryonic shoot (epicotyl + hypocotyl)
- endosperm layer 1 cell thick
the structure of a mature monocot seed?
- 1 cotyledon
- pericarp infused with seed coat
- radicle
- embryonic shoot (epicotyl + hypocotyl)
- coleorhiza
- coleoptile
which angiosperm has more endosperm in their mature seeds?
monocots
what makes up the embryonic shoots in angiosperm seeds?
- hypocotyl
- epicotyl
coleoptile
two sheathes the enclose the embryo, covers the young shoot
seed dormancy
protects the seed until conditions are right - increases the chances that germination occurs
germination depends on ___, which is the uptake of water due to low water potential of a dry seed
imbibition
what emerges first during seed germination?
the radicle, which is the embryonic root
function of a root?
- anchors the plant
- absorbs minerals + water
- stores carbs
root hairs
increase surface area
what do mycorhizas (soil fungi) do?
form mutualistic association
- plant secretes carbon and sugar : fuel for fungi
- fungi increases surface area : increase nutrient intake
root cap
produced by the RAM, protects the root tip as it grows through soil
3 growth zones behind root tip?
- zone of cell division
- zone of elongation
- zone of differentiation, or maturation
where does the majority of nutrition of water intake occur?
the zone of differentation
why does the root cap secrete polysaccharide slime?
helps to lube the root tips to get into the ground
why does the root cap produce signals?
to attract beneficial microbes like bacteria and fungi
which ground tissue cells fill majority of the cortex?
parenchyma cells
what is the innermost layer of the cortex called, and its function?
endodermis - regulates passage of substances from soil into the vascular cylinder
cortex function?
stores sugar
in many monocots, the core parenchyma cells are surrounded by?
rings of xylem, then phloem
what is the outermost cell layer in the vascular cylinder?
the pericycle
what arises from within the pericycle?
lateral roots
