lecture 6 Flashcards
what part of the plant absorbs the most water
the root hairs
what is the area of growth for the root
the root tip
what are the two ways water moves throughout the plant
apoplast and symplast
what is apoplast water movement (3 important things)
water travels through the CELLULOSE filled cell walls and intercellular spaces, h2o never cross a membrane, plant has no say over water movement in this pathway
what is symplast water movement (three important things)
continuous water movement though the cytoplasm of cells CONNECTED by the plasmodesmata, plasma membrane controls movement (osmosis), plants have a say on what they want inside (REQUIRES ENERGY)
what stops apoplast water movement
casparian strip
what is the casparian strip
water impermeable (wax) sealing space in between cells and doesnt let water travel through cell walls
what is the vascular tissue of a plant
xylem and phloem
what is transpiration
movement of water vapor out of the leaf and into the atmosphere through the stomata
what is evaporation
movement of water vapor from the cell walls of spongy mesophyll cells into the intercellular space
is the movement of water vapor active or passive
passive
what creates negative pressure in the leaf
when transpiration occurs, it deepens the meniscus of water in the leaf
how does tension occur
created when transpiration pulls h20 molecules to fill the gap in the xylem drawing h20 upward
what is cohesion
water sticking together
what is adhesion
water sticking to other things
what is the apical meristem
the location in which a plant grows , it grows at the top and it gets longer from the tips of the stems and the roots
what are the three systems of a vascular plant
dermal, ground, vascular tissue
in what plants are stomata found
mosses, hornworts, and vascular plants
what happens when stomatas are opened
co2 is free to enter, o2 is free to leave, h2o evaporates an leaves the leaf tissue
what happens when stomatas are closed
co2 can be depleted by photosynthesis , o2 can be accumulated and that inhibits photosynthesis, and h2o gets trapped in leaf
how do stomata work in seed free, mosses, and some vascular plants
stomata opens when cells are turgid (full of water) and close when flaccid. when central vacuole is filled the cell has turgor pressure making it firm.
how do stomata work in seed plants
a proton pump responds to light to change osmosis pressure potential of guard cells so that they swell and open (uses energy)
what do stomata do during the day
stomata opens to allow co2 to enter
what do stomata do during the night
stomata closes to conserve h2o
where does stomata control water transport
through the xylem
how do tall trees water their leaves
this process is controlled by evaporation and doesnt need energy, increased evaporation increases force and rate of h20 so water movement happens more on hot dry windy days
when does evaporation ever stop
when theres no h2o in soil
when does evaporation and transpiration occur mostly
on hot dry windy days rather than cool rainy days
spermatophytes are
seed plants
what is secondary growth
cell division that causes stems and roots to thicken
what is primary growth
cell division that occurs at the tips of stems and roots
what is wood
secondary xylem
how is wood created
by secondary growth
what two things are wood and bark derived from
2 lateral meristems
what are the two lateral meristems
vascular cambium and cork cambium
vascular cambium
produces secondary xylem (wood) and secondary phloem (inner bark)
cork cambium
produces waxy walled protective cells , some die and become outer bark
as you go to the center of the tree, what do you find
the older parts of the tree
what does the vascular cambium do as the tree grows
the VC stops being in clusters of cells and becomes a cylinder making secondary xylem and secondary phloem expanding the diameter of the tree
what does the cork cambium do
makes the cork cells that end up being bark
what happens to the secondary xylem after a season has passed
the VC makes another secondary xylem by pushing it self outwards and the old secondary xylem becomes a ring inside of the tree
what does the secondary xylem do
cannot carry water but allows support so that primary growth can occur
what does the secondary phloem do
it has the live cells crush up against the cork cambium until it dies because only one secondary phloem can exist as the same time
what is the difference between secondary xylem and secondary phloem
secondary xylem accumulates year after year while the secondary phloem gets crushed and dies
