component 3 plant transport

what does a large surface area of leaf allow for gas exchange and photosynthesis

allows for more stomata for gas exchange allows more light to be absorbed as there are more chloroplasts for photosynphesis

what does a thin leaf allow for gas exchange and for photosynthesis

gas exchange: short diffusion pathway

photosynthesis: allows light to penetrate leaf so absorbed by all cells

what does a transparent leaf allow for in photosynthesis

can pass into leaf for photosynthesis

what does long palasade cells full of chloroplast allow for in photosythesis

maximise the light absorbed packed cells together with as many chloroplasts as possible

what does airspaces in leaf allow for in photosynthesis and gas exchange

gas exchange: allow free diffusion of gasses between stomata and cell

photosynthesis: allow co2 to diffuse to photosythesising cell

what does stomata in leaf allow for in gas exchange and photosynthesis

gas exchange: allows gases to enter and leave leaf

photosynthesis:allow co2 in leaf

what is primarily happening in leaf in day

photosynthesis

what is primarily happening in night in leaf and why

respiration no light for photosynthesis

in the day what is relation ship between o2 and co2 in leaf

as more photosynthesis than respiration so co2 is taken in and o2 is given out

in the night what is the relationship between co2 and o2

in night more respiration than photosynphesis so o2 in co2 out

what is the function of the waxy cuticle and what is it made off

stops water being lost made of lipid

what is the function of guard cell

used to controll water loss and gas exchange in stomata

how do guard cells open

need a lower waterpotential so k+ ions activly transported in guard cell with atp from photosynthesis and insoluble starch converted into soluble sugar

so water moves into guard cell down a water potential gradient by osmosis

guard cell becomes turgid so stomata opens because cellulose is thicker next to stomata causing the guard cell to bend

how do guard cells close

need a higher water potential so k+ ions facilitated diffusion out of cell down conc gradient soluble matate converted into starch

so water moves out of cell by osmosis

guard cell becomes flacid so stomata closes

how can a practicle to find stomatal density be done

add a thin layer of nail varnish in a half cm squared section on the bottom of leaf

place piece of tape over the varnish and peel away

place tape on a slide then on a microscope stage count stomata in the highest power then use pi r squared to find area of eye pieve and use stomata to find density

what should be controlled in stomata density practicle

humidity

airflow

what does standard deviation show

the spread of data around the mean the lower the standard deviation the more reliable the result

what are the features of a mesophyte

few stomata on upper surface

many stomata on lower surface to reduce water loss

waxy cuticle on upper surface to avoid water loss

no cuticle on lower surface

air spaces present to allow diffusion

no hairs

what are features of a xerophyte

many stomata on upper surface

no stomata on lower surface

thick waxy cuticle on upper surface

thick waxy cuticle on rolled leaves lower surface

air spaces present

hairs present

sunken stomata

rolled leaves

what are features of a hydrophyte

stomata present only on upper surface

little to no waxy cuticle on upper none on lower as water loss not needed to be prevented

large airspaces for boyency

no hair

what is the symplast pathway

water moves through the cytoplasm and plasmodensmata

what is the apoplast pathway

water moves through cellulose cell walls through

what is the vascuolar pathway

water moves through vacoules cytoplasm and plasmodensmata

what is the casparian strip

surronds cells of endodermis prevents water and minerals from seeping between cells to get into vascualr cylinder water must pass through cell membranes

why does cohesion cause water to enter leaves

water molecules are attracted to each other so trasnpiration at leaf causes a transpitarion stream

why does adhesion cause water to enter leaves

due to attraction water will move upwards when tubes are narrow like xylem

how does root pressure cause water to enter leaves

nitrate ions are activly transported into cell of endodermis this lowers the water potential in that area causing water to move in via osmosis this created hydrostatic pressure forcing water in the xylem up

what is parenchyma

living tissue

what is the xylem made off

tracheids and vessels

what is the function of trachieds

provide support as narrow

what are pits in xylem

gaps in lignin allowing water to leave tube

why is xylem imperiable

made of dead material called lignin

what are the factors that affect transpiration

humidity as humidity inc trans dec

temp as temp inc trans inc

airflow as airflow inc trans inc

light intensity as light inc trans inc

why does water uptake not equal water used in traspiration

water could be used in photosynthesis

some stays in cell to make turgid

used in hydrolysis

made by respiration

what are the 9 steps of transpiration

1. water evaporates from surface of epidermal cell

2. water diffuses from sub stomatal chamber into atmosphere

3. water evapotates from cellulose cell wall of palaside and spongy mesophyll into sub stomatal chamber

4. water moves through leaf tissues via apoplast symplast and vascuolar pathway into leaf

5. water leaves xylem via vessels with little ligninification moves into apoplast due to cohesion and other pathways by osmosis

6. water is drawn up xylem as transpiration causes neg pressure in xylem so water forms a continous stream due to cohesion and adhesion

7. water enters xylem through porly ligninfied cell walls due to cohesion from apoplast and osmosis from other pathways

8. casparian strip prevents water enetering between cells water must go though a cell membrane

9. water is uptaken by ososis along a water into root hair cells

why does inc temp inc transpiration

higher temp inc ke of water so they diffuse more quickly

warm air also has more ke and holds more water

why does inc in humidity dec transpiration

dry air outside creates a steeper diffusion gradient

why does inc in air movment in transpiration

blows air maintaining conc gradient allowing more transpiration

why does inc in light intenstity inc transpiration

affects degree of opening and closing of stomata

how can tranpiration of a plant be messured

use a potometer

1.cut shoot underwater to stop air entering xylem

2. cut shoot at a slant to inc surface area

3. check apperatus is full of water

4. insert shoot into apparatus under water

5. shut screw clip

6. remove potometer from water and ensure airtight joints around shoot use vaseline

7. dry leaves and leave in constant conditions

8. messure how far air bubble moves

what is an example of a source in a plant

leaves (where sugar is made)

what is an example of a sink in plants

growing areas (where sugar is stored)

explain mass flow and how it is used to transport materials

source contains lots of material so low water potential water enters source by osmosis inc hydrostatic pressure

fluid is pushed from an area of high hydrostatic pressure to and area of low hydrostatic pressure

fluid enters sink material is used to water potential increases and h20 leves dec hydrostatic pressure

what are the 6 steps of translocation

1. h+ is activly transported from companion cell into source cell

2. h+ ions move back into compaion cell when combined with sucrose in co transport down dif grad

3. sucrose diffuses into sieve tube element by diffusion through paslmodensmata

4. low water potential in sieve tube so water moves into sieve tube by osmosis inc hydrostatic presussure

5. at sink sucrose is removed and stored raising water potential water moves into xylem out of sink dec hydro static pressure

6. phloem sap is pushed from source to sink down a pressure gradient

what is the experimental evidence for translocation ( mass flow)

1. ringning expermiment (removal of phloem) shows accumulation of sucrose products on leaf side of ring but none on root. therfore sucrose was blocked by removal of phloem. so phloem is route of transport

2. using aphids to sample sap. aphid stylus extends into sieve tube laser is used to remove stylus sap drips out can be analysed to show that succrose is carried in phloem both above and below leaves and high pressure in phloem

3. radioactive labelling of co2 which will become incorporated into sucrose can be used in conjunction with aphids to determin rate of transpiration

4. source and sinks can be determined by autoadiogrpahy using radioacitve co2

what is the evidence against mass flow

sieve plates impede flow

traslocation is faster than expected with diffusion

this theory doesnt explain bidrectional flow or diffrent rates of flow of sucrose and amino acids

does not explain companion cell mitochondria high o2 intake or stopping of translocation by cyanide but not transpiration

what is alternative theory to mass flow

streaming in cytoplasm of sieve tubes could be resposible for bidirectional movment

what is translocation

Sugars produced in photosynthesis are transported from the leaves (source) to other parts of the plant (sink) for respiration and other processes.

what is transpiration

the process of water movment through the plant