Mass transport in plants Flashcards
(17 cards)
what is water required for in plants
photosynthesis and maintain cell structure
what re minerals needed for in plants
production of important biological molecules , eg. proterins and chlorophyll
what transports water and dissolved minerals in a plant
xylem
how are xylem specialised
hollow tuves with no end walls - constant water flow
lignin waterproofs the tubes
lignin also strengthens the xylem to reduce breakages
what is the upward movement of water in thwe xylem caused by
transpiration in the leaves
how does transpiration drive water movement in xylem
water diffuses out of leaves
loss of water vapour lowers the water potential in the cells in the leaf
water in mesophyll cells evaporates into the leaf cell lowering wp of the mesophyll cells
water is drawn up from the xylerm into mesophyll by osmosis
water moves up contuniously
what do we call the upward movement in the xylem
transpiration stream
water is under tension so called cohesion tension
how are water molecules chemically moved up xylem
hydrogen bonds
definition of transpiration
the loss of water vapour via the stomata by diffusion
definition of the transpiration stream
movement of water from the roots to the leaves
why is transpiration needed
provides a means of cooling for the plant
uptake of mineral ions
turgor pressure in the xylem provides support to leaves
factors affecting transpiration rate
humidity light temp wind
change the wp gradient
what happens if the transpiration rate increases,
there is a stronger transpiration pull
how does movement of water through the cell walls occur
by the apoplast
how does movement across the cytoplasm occur
symplast
when do the guard cells open the stomata
when they are turgid (thus resulting in a higher rate of transpiration)
