Lecture 6 Flashcards
what are the primary functions of roots
anchorage, absorption, conduction of water and minerals, storage of food, synthesis of hormones and secondary metabolites
what is the primary root
first root that originates in the embryo
where are taproot systems found
in gymnosperms, magnolids, and eudicots
where are fibrous root systems found
monocots
what is the root system dependent on
soil moisture, soil temp, and soil composition
where are feeder roots located
in upper portions of the soil
when is the root-to-shoot ratio the highest
in seedlings
how does the root-to-shoot ratio change with age
decreases with age
what is the structure and function of the rootcap
parenchyma cells, protects root apical meristem, aids in root penetration, responds to gravity, peripheral cells slough off, mucigel
what are the 3 stages in the primary development
cell division, elongation, maturation
what are the 3 tissue systems in roots
dermal, ground, and vascular
where are root hairs located
on the epidermis
why are mycorrhizae important
they increase surface area
what is the cortex
occupies most of the area of the roots, plastids usually store starch, contains numerous intercellular air spaces,
what are casparian strips
portion of primary wall and middle lamella with suberin and sometimes lignin, restricts substance movement
where are casparian strips located
in both the endodermis and exodermis
what is the exodermis
the outer most layer of the cortex that may replace dead epidermis as the protective layer
what is in the pericycle
non-vascular cells
where is the pericycle located
vascular cylinder
what may give rise to cork cambium
pericycle
where do lateral roots arise
pericycle
what replaces the epidermis in woody roots
periderm
what are origins of lateral roots
origniate in pericyle, divisions occur some distance behind region of elongation, root primordium
what are adventitious roots
stem-borne roots
what are aerial roots
produced from aboveground, may serve as prop roots
what are air roots
pneumatophores
