Transport In Plants

Front 1

why do plants need a transport system?

Back 1

all living things need to take substances from their environment and get rid of waste.

Front 2

what do cells need a constant supply of?

Back 2

oxygen

Front 3

what cells in a plant could survive without a transport system and why?

Back 3

epithelial cells because they are close to the surface and can diffuse enough oxygen

Front 4

whats the main problem with the roots and the leaves?

Back 4

+roots
-can take up water but cant take up sugars

+leaves
-produce sugars easily but cant take water from the air.

hence they both work together

Front 5

what does the vascular tissue do?

Back 5

move substance up or down
water travels up only in the xylem
food and sugars travel up and/or down in the phloem

Front 6

what does not travel in the vascular tissue?

Back 6

gases e.g oxygen and carbon dioxide

Front 7

state some properties of the vascular tissues

Back 7

-distributed throughout the plant
-doesnt require a pump
-xylem and ploem are found together in the vascular bundles
-contains other tissues that give support and strength
-a specialised tissue

Front 8

describe xylem and phloem in the roots

Back 8

-at the centre of a young root
-central core is of xylem, looks like an + or x.
-phloem is found in the centre of these sections
-provides strength

Front 9

where is the endodermis found?

Back 9

around the vascular bundle

Front 10

what is inside the endodermis and do they do?

Back 10

meristem cells. they are the only cells that divide by mitosis in a plant. they are also stem cells that can specialise into anything required

Front 11

what is the pericycle?

Back 11

the vascular bundle being surrounded by endodermis that contain meristem cells

Front 12

descire xylem and phloem in the stems

Back 12

-vascular bundles found near the outer edge of the stem
-in non-woody plants bundles are seperate and discrete
-in woody plants bundlesbecome continuous as they age.
-provides support and flexibility

Front 13

where are xylem and phloem found in the stem?

Back 13

-xylem is found on the inside of vascular bundles
-phloem is on the outsied of the vascular bundles
-inbetween phloem and xylem is the cambium
-the cambium contains meristem cells

Front 14

describe vascukar bundles in the leaf

Back 14

-vascular bundles form the midrib and veins of the leaf
-2 categories of plants: seed leaves or dicotyledons
-dicotyledons have a network of branching veins that get smaller as they spread
-inside the veins the xylem is on top of the phloem
-

Front 15

what does xylem consist of?

Back 15

tubes
dissolved minerals
fibres

Front 16

how does lignin create xylem vessels?

Back 16

-xylem are long and have thick cells
-they are coated in lignin which waterproofs the cell walls
-as a result to the waterproffing lignin the cells, end cells and contents die and decay
-this leaves a xylem vessel
-this is strengthened by the lignin.

Front 17

what patterns do the lignin form and what is their job?

Back 17

spiral, annular (rings) or reticulate (broken rings) patterns. their job is to allow flexibility on the vessels.

Front 18

how are pits made and what do they do?

Back 18

pits are formed when the lignin is not complete and it leaves pores in the walls. they allow water to leave one vessel and pass to a different one

Front 19

what are the adaptations of xylem?

Back 19

-continous column
-narrow so yube doesnt break and capillary action is effective
-lignin ti give support and allow flexibilty when growing or bending
-no nucleus or cytoplasm, end walls or contents

Front 20

what is the structure of phloem?

Back 20

-transports sugars to one part of the plant to another
-can go up or down
-has two types of cells: sieve tube elements and companion cells

Front 21

describe sieve tubes

Back 21

-have no nucleus and little cytoplasm
-usually transport sucrose which is dissolved in water to form sap
-lined up end to end
-contains cross walls at intervals that are perforated to allow sap to flow. called sieve plates
-sieve tubes have very thin walls and have 5-6 sides

Front 22

describe companion cells

Back 22

-in between sieve tubes
-large nucleus, dense cytoplasm and lots of mitochrondria
-carry out metabolic processes needed by sieve tubes, which requires energy
-ATP used for loading sucrose into sieve tubes
-cytoplasm linked through plasmodesmata

Front 23

what is the plasmodesmata?

Back 23

gaps in the cell walls allowing communication and flow of minerals between cells

Front 24

what does the pitch for sign stand for?

Back 24

water potential

Front 25

whaere does water move to and from?

Back 25

from a region of hight water potential to an area of low water potential, down a water potential gradient

Front 26

what is the water potential of pure water?

Back 26

0

Front 27

as more salt and/sugars are added what happens to the water potential?

Back 27

becomes a negative and gets a bigger naegative the more added

Front 28

why do cells never have a water potential of 0?

Back 28

because they have cytoplasm that contains solutes

Front 29

how does water move?

Back 29

by osmosis

Front 30

if plant cells are put into pure water what will happen and why?

Back 30

-it will take up water by osmosis
-because there is lower water potential outside of the cell than inside, so it moves into the cell where water potential is higher

Front 31

when plant cells take up water why dont they burst?

Back 31

-because they have a strong cellulose cell wall
-it becomes turgid but never bursts

Front 32

what is pressure potential in a plant?

Back 32

the amount of water pushing on the inside of the wall. as this build up during water intake it reduces intake (influx)

Front 33

if a cell is placed in a very strong solution (low water potential) why will it lose water?

Back 33

-because the water potential of the cell will be higher than that of the solution.
-therefore it will move to a lower potential which is outside the cell.

Front 34

what is incipient plasmolysis?

Back 34

when the cytoplasm of a plant doesnt push against the wall.

Front 35

what is plasmolysis?

Back 35

when the plasma membrane loses contact with the cell wall.

Front 36

if one cell was -800 and the other was -1500 which way would the water move

Back 36

-800----->-1500
less----->high

Front 37

what are the 3 routes water can take?

Back 37

apoplast
symplast
vacuolar

Front 38

describe the apoplast pathway

Back 38

-moves through the spaces between the cells.
-spaces between the cells are filled with cellulose molecules
-DOESNT pass through plasma membranes or the cells themselves
-no nutrients enters the cells at all

Front 39

describe the symplast pathway

Back 39

-water enters the cell by the plasma membrane
-travels in the cytpolasm through the plasmodesmata from one cell to the next

Front 40

describe the vacuolar pathway

Back 40

-water enters through plasma membrane
-travels from one cell to the next by the plasmodesmata
-free to move throughput the cytoplasm AND the vacuoles

Front 41

turgid

Back 41

whan a plant cell has absorbes as much water as possible

Front 42

plasmolysis

Back 42

whan plasma membrane loses contact with the cell wall

Front 43

what is transpiration?

Back 43

water moves into the plant by the roots, up the stem by the xylem into the leaves and lost by evaporation into the atmosphere

Front 44

what is translocation?

Back 44

the movement of (assimilates) sugars up and down and side to side in the plant

Front 45

what is the casparian strip?

Back 45

a tight band around the root cells preventing backflow of water and the water taking the apoplast pathway

Front 46

whare is the casparian strip found?

Back 46

root cells

Front 47

how does the casparian strip work?

Back 47

-transpoter cells in the membrane
-lowers the water potential in the xylem so the water from the cortex (outside if the xylem) flows back to the xylem
-generates root water pressure
-transpiration maintains the water potential pressure
-capillary action of water is generated by cohesive property of water

Front 48

how are water molecules attracted to each other?

Back 48

by cohesion

Front 49

describe how transpiration works

Back 49

-waqter molecules attracted to each other by cohesion and form a long chain
-molecules are lost at the top of the chain through the leaves
-as this happens the chain is pulled up creating a tension which is strengthened by the ligniated xylem cells.

Front 50

what happens in the xylem if the water column is broken?

Back 50

its maintained by another vessel via the pits

Front 51

how do minerals enter plant cells?

Back 51

by active transport requiring ATP energy

Front 52

what is the cortex?

Back 52

tissue between the epidermis and the vascular bundles

Front 53

describe cohesion

Back 53

the attraction between the SAME molecules. in plants its between water molecules and forms a chain of them

Front 54

what is adhesion?

Back 54

the attraction between DIFFERENT molecules

Front 55

where is the stomata and what does it do?

Back 55

on the underneath of a leaf, it opens and closes allowing different amounts of gases into and out of the plant

Front 56

dewcibe the function of the guard cells

Back 56

-either side of the stomata
-when turgid open the stoma
-when plasmolysed they close the stomata

Front 57

describe water potential

Back 57

-measured in kPa
-moves from high to low water potential down a water potential gradient. e.g-800----->-1500
-generated by water pushing on the cell wall.

Front 58

what are xylem and phloem?

Back 58

tissues because they have cells that work together to perform a particular function

Front 59

what is the endodermis?

Back 59

-around the vascular bundles, containing layers of meristem cells (only cells that divide by mitosis)

Front 60

how do you measure photosynthesis?

Back 60

with a potometer

Front 61

when using a potometer what must you remember to do?

Back 61

-cut and join the stem under water
-seal it with vaseline so no water can be lost

Front 62

describe the process of active loading within the phloem

Back 62

-companion cells use ATP energy to transport hydrogen ions out of the cells into the surrounding tissues creating a concentration gradient
-hydrogen ions diffuse down a concentration gradient back into the companion cells through cotransporter proteins
-hydrogen ions then bring sucrose molecules into the companion cell with them
-as the concentration of sucrose builds up in the companion cells it will start to diffuse to the sieve tube elements via the plasmodesmata

Front 63

how does sucrose move along the phloem?

Back 63

-sucrose is actively loaded into the sieve tube elements and reduces water potential
-water increases the hydrostatic pressure as it flows by osmosis.
-water moves down the sieve tube element from the hydrostatic pressure at the source, to the sink where there is low hydrostatic pressure
-sucrose is removed by surrounding cells that require it, increasing the water potential in the sieve tube elements
-water then moves out of the sieve tube reducing the hydrostatic pressure.

Front 64

what is the source?

Back 64

part of the plant which releases sucrose into the phloem

Front 65

what is the sink?

Back 65

part of the plant that removes sucrose.

Front 66

where is the sink found and what is it used for?

Back 66

-found ANYWHERE in the plant
-sucros found at the sink can be used by any cells close by for respiration

Front 67

how does surcose move and does it affect anythng?

Back 67

-sucrose moves by diffusion or active transport
-this affects water potential so that molecules can move into surrounding cells
-reduces hydrostatic pressure in the phloem at the sink
-this process generates MASS FLOW where water can move up OR down in the phloem

Front 68

what affects water loss in plants?

Back 68

-light
-temp
-presence of cuticles
-amount of leaves
-number size and position of stomata

Front 69

how does number of leaves affect water loss?

Back 69

more leaves=greater surface area therefore more vaour can be lost

Front 70

what is a xerophyte?

Back 70

a plant that is adapted to reduce water loss so it can survive in very dry condidtions

Front 71

name and explain 1 unavoidable loss

Back 71

transpiration because when the stomata open for gas exchange there is an easy route for water vapour tp be lost as it moves down a concentration gradient into the atmosphere

Front 72

how do plants reduce water loss?

Back 72

-they have a waxy cuticle which prevents evapotation through the epidermis
-stomata are found on the bottom of the leaf so the sun cant get to it directly
-stomata close at night time when there is no light for photosynthesis
-deciduous plants lose their leaves in the winter when it is too cold to photosynthesise and there is little water available due to frozen ground

Front 73

what will happen if plants lose too much water?

Back 73

-they will suffer water stress
-cells will loses turgidity and may become plasmolyssed
-plants will wilt
-eventually die

Front 74

how are xerphytes adapted to living in arid or very dry condition?

Back 74

-leaves shaped like needles to reduce surface area
-densely packed mesophyll layer so water vapour cant go into these spaces (if it did more water would be needed)
-thick waxy cuticle
-hairs on surface that trap air and in turn the water vapour. this stops the plant from loosing water vapour as water potential is equal inside and outside
-rolling of the leaves so the lower epidermis isnt exposed to the atmosphere, lowereing or even eliminating potential gradient