Biology (Plant Transport) Flashcards
Like in animals in large multicellular organims only the epthelias, the..?
surface cells can get nutirents through simple diffusion
xylem travels..?
phloem travels..?
water up the planrt
sugars like sucrose up and down the plant
Xylem and phloem are arrnaged in vascuakr bundles to provide..?
strength
Xylem and phloem in the young root?
Xyklem (+ shape), Phloem (arms of the + shhape)
arrnagement provides flexibility/strenth with the pulling forces of the wind
Xylem and phloem in the stem?
circle ,middle area = cortex, vascualr bundles, phloem= outside, xylem= middle,
in the middle- layer of cambium (meristem cells that divide)
non wody plants= seperate/woody plants= bundles are cotnionius- provides a compete ring to withstand enidng forces of the wind
xylem and phloem in the leaf?
central midrib- v shaped/veins get smaller as you move away from it/xylem= top, phloem= bottom
xylem vessels are..?
transport water
long cells>been impregenated with lignin wich waterporrfs the cell as ti devlops>causes the cell to die (contents and end walls to decay)>long continous column of dead cells
what is the purpose of lignin thogh?
Strengthens the cell
Adaptations of xylem tube vessels?
1) The ring pattern of lignin provides flexibility
2) Lignification isn’t complete>reusults in pits which allow water to travel into adjacent tubes
3) No content- no cytopasm or nulclues- flow of water is not impeded
Sieve tube elemtents?
little cytyoplam/no nuclus
cross-walls at intervals to allow flow of sap (sucrose dissolved in water>flows through tube)
Companion cells?
dense cytoplam/nuclues
contian many mitochondria with ATP for active processes e.g. loading phloem into sieve tube elements
plasmodemata- gaps to allow flow of minerals between sieve elements and comapnion cells
Osmosis is when..?
water molecuels move from a region of high water potential to low water potential across a partialyl permable membrane
If too much water is coming into the cell then?
- danger of it bursting
-one cell is full of water>turgid
Water inside the clel exerts a pressure on the cell wall, called the pressur potential, warning it its full>influx of water is reduced
If too much water is leaving the plant?
cell loses its turgidity>cytoplam and vacuole shrink>cytoplam pushes away from cellwall (incipient plasmosis)>loes contact with cell wall (plasymolsis)
Minerals move from soil into root hari cells by..?
active transport>reduces water potenial>water moves by osmosis into root hair cells>The endothermis layer(surrounding the xylem)>contains starch-[evidance for growth]
- water can o=move through cell walls 9apoplast pathway)
- though plasmodemata (sympoat pathway)
- vacuoles (vacoular pathway)
What forces the water diwn the syplast pathway?
Endothermis consists of a casparian strip - made of suberin (deflects water and ions thorugh cytoplasm) which forces water down the symplast pathway (blocks the apoplast pathway- waterproofs it)
Forces it through cytoplasma nd cell membrane>contiasn transporter proteins>transport dissolved niotrate ions into through the cortex (parachyma cells) into the xylem>reduces the water potential in the xylem>water moves in through osmosis
The water in the apoplast and syplast pathway can..?
join up jsut before passing thoruhg the endothermis
How does water move from the xylem tube into the leaves?
rot pressure= expalins a small amount of water lost from being pushed up the xylem tube
Most is due to cohesion (strong attraction between water molecules)>stick together as a chain>water leaving the tube at the top opulls up the chain as a contionous column (creates tension-low hydostatic pressure) [ cohhesion-tension theory]
If xylem tube is broken, water can move sideqays through pits
Capillary action- small amount - water moelcuels tick to the side [adhesion] and get pulled up
How does water leave the leaf?
water that moves into leaf(from the xylem into the leaves [ mesophyll cells] by osmosis>water evaporates from mesophyll cells into large air spaces and collects as water vapour>When the water vapour is higher than outside air it diffuses out of the intercelluar spaces
How does water keep moving by osmosis across leaf ?
evporates from mesophyll cells>cell spaces
evaporation= loss of water>casue water to move from neighbouring cells due to their higher water potential and this contuijes until water is entering the innermost leaf cells
Transpiration is the loss of water through the .>?
upper areas of the plant, mostly through the leaves
Exhnage of gasse- gain of 02/removal of C02 is has to be done though the ..imeeiately above the guard cells?
stomata
For the somata to be kept open it means easy loss of ..?
water
Xerophytes are plants that are adapted to living in..?
dry/arid condtions
Marram grassare adapted to lving ons and dunes becuase:?
- hairs on leaves/stomata in pits- trap a alyer of moisuture- reduce water vapour potential gradient
- thick waxy cuticle- recduces evaporation from epidermis
Cacti?
- spines instead of elaves- reduces SA
- hair0-thin roots to colelct moisure (long)
- stem swells in times of moisuitre
Joshua Tree?
-2 root sytem- one buried deep (store surplus water)/one shallower- to collectw ater
spiny leave sturned upwards o colect mositure
-grow in places with high water avaolaibity
Transpiration factors:External?
Light- stomata in light (during the day)>increase rate of transpiration- fewer photons og light hitting water’s surface-causign it to evaporate more
Teemepraure- increase rate of transpiration becuase water moelcuels ahev more kinetic energy/increase wate vapour poential in kleaf and decrease it in air
Wind Speed- increase transpiraiton as ti carries awy weater moelcuels faster increasuing th water vapour diffusion gradient
water availability- less in sopil- less can be taken up by plat- decreases transpiration
transpiration factors: Internal?
number of leaves- more leaves>bigger SA
more stomata- more water lost
A potomater is..?
a glas tube used to measure the water uptake of a plant
How is a potpometer used?
1) The leafy shoot is cut under water to ensure no air enters the xylem
2) Th epotomter is filled completely to ensure there are no air bubbles
3) Using a rubber tube the elafy shoot is tied to the potomter (glas tube)
4) The tube is clamped to a stand that a ruler attached to it
5) The movement of of the air buuble (meniscus) is measured over a given time>from this water uptake can be calculated
volume of water lost againsr time in minutes
6) Once the air bubble reaches the junction of the resiovoir tube and capillary tube the tap on the resiovoir is opened and the syringe is pushed down until the air bubble is pushed back to the start of the calibration on the capillary tube
Measuring the water uptake of a plant is not the same as measuring the volume of water lost by transoiration as ..?
water is used up by photosynthesis, retianign turgidity so value will be less
Transolcation is
source is
sink is?
movement of sugars up a plant
sucrose isn released into th ploem
sucrose is removed from the ploem
How does sucros move into phloem>sieve tube elements?
Companion cells use ATP to transport H+ ions into the surrounding tissue>creates a diffusion graident>H+ ions move back into the companion cells (facialiated diffusion through co-transporter proteins)>bring sucrose with them>sucros diffuses into sieve tube elemts though plasmodesmate (syplast [pathway)
At the sink where sucrose is loaded in..?
Sucros moving into sieve tube>lowers water potnetial>water moves into sieve tube elemetns by osmosis>creates hydostatic pressure in sieve tube elements at source
Water moves down sieve tube elments to the sink..?
from a high hydrostatic presure>low pressure
At the sink..?
sucros is stored as starch/used in repiration which means surcos moves out into surrounding cells.increases water potential>water molecuels move out by osmosis>reduces hydrostaic pressure at the sink
mass potometer measures= ?
mass of water lost by transpiration
layer of oil/plastic prevents ?
evaporation of water
Limitiations of potomter?
1) Using oen cutting will keep the surace area of transpiration constant- using differnet cuttings will affect total transiration rates due o changes in surface area
2) Althogh data can eb concluded quickly> surface area of plants is too hard to meausre accurately
What prodcues a mass flow?
The water moves down the hydostatic pressrue graident, it proiduces a water flow>carries nutrients along the phloem (can occur up and down the plant)
How can both the leaves and roots act as sources and sinks?
leaves- late sopring- glucose converted to sucrose (from photosynthesis)>loaded into ploem [source]
early spring when leaves need to grow>leaves act as a sink
root supplies energy instead>carbohyratesare reladsed into phloem
roots= sink- stores carbohydtates in summer
Evidance for trasnolaction: Ringing a tree?
growing season- leaves prodcue glucose>converted tio surcose which moves down the plant by translocation (soruce>sink)
ring the tree- bark above it swells- sucrose soltuion can’t get past to sink
bark below shriks- deficient- no further growth
Transolation evidance: aphid
aphid (insect- has adapted mouthparts to it the stem (feeds on it)> stylet peirces phloem>fluid collected from aphid is analysed (contians many sugars)
Translocation evidance: that it uses ATP
Comoanion cells contian mitochondria>produce ATP
if you use a metabolic poison of cyanide- it inhibits the formation of ATP
Translocation evidance: radioactive carbon?
if you expose a leaf to 14C (radioactive carbon) it forms soluble carbohydrates during photosynthesis (largelt resitricted to phloem on a photgraphic plate)
