Roots 1 Flashcards
Major functions of plant roots
anchoring the plant in the soil
absorption of water and nutrients
transport of water and nutrients to the rest of the plant body
where do roots originate
formed in the embryo as a radicle when initiated at the root apical meristem
2 main patterns for root organization
fibrous root and tap root
where do lateral roots develop
from the pericycle in response to chemical signals (plant hormones)
where do root hairs develop from
the epidermis
root hair function
increase root’s surface area for uptake of water and nutrients
where do adventitious roots develop from
from stems and leaves in stem cortical cells
roles of water in plant cells
structure (turgor)
cooling
photosynthesis
transport
apoplast
water movement outside the cell
symplast
water movement within the cell
how does water move cell to cell
apoplast and symplast
how does water move between organs (vascular tissue)
xylem and phloem
how does water move from environment to plant
water uptake and evaporation
cell types involved in water movement
vessel elements and tracheids (xylem) (V)
sieve tubes and companion cells (phloem) (V)
roots hairs (D)
guard cells (D)
endodermis (G)
roots are adapted to _______ water uptake
maximize
Intracellular route of water
via cell interiors, through plasmodesmata (symplast)
Extracellular route of water
via cell cells (apoplast)
Casparian strip
a hydrophobic barrier in the transverse and radial wall of the endodermal cells
how is movement blocked in the apoplast
by the casparian strip
osmosis
the movement of water through the semi-permeable membrane from an area of low concentration to one of higher solute concentration
water potential
describes the movement of water in plants (move from area of high water potential to area of lower water potential
what is an example of what plants do to prevent water loss to the soil
when the soil is dry, the aquaporins close to slow rate of water loss. During prolonged periods of drought, aquaporin gene expression can decrease in the roots.
how do solutes move across gradients
the move based on concentration gradients
root pressure
if the solute concentration becomes high enough, pressure can develop in the roots, especially when there is a lot of water in the soil
what does root pressure do and what is it called
root pressure can drive limited amounts of water from the roots to other parts of the plant
called guttation
T/F: guttation (root pressure) is the main mechanism plants use for water uptake or xylem transport
F. It is not the main mechanism
