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Biology Mark scheme flashcards > Transport in plants > Flashcards

Transport in plants Flashcards

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1
Q

State three features of the leaf hown above which indicate that it live in a dry environment and explain these features (6)

A
  • thick cuticle - waterproofing
  • curled - trapping water
  • hairs - trap water
  • sunken stomata - trapping water vapour
  • surface area - less area which water can be lost
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2
Q

What is the name given to plants that live in dry environments (1)

A

xerophytes

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3
Q

What the role of the xylem (1)

A
  • transports water and minerals
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4
Q

What is the role of phloem (1)

A
  • transports sucrose and amino acids
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5
Q

Explain how epidermal cells carry out its function in the uptake of water and minerals in the plant (4)

A
  • waterproof as casparian strip is impregnated in suberin
  • blocks apoplast pathway
  • active trasport of minerals by endodermal cells
  • into symplast pathway
  • active tranport of minerals into pericycle
  • water follows via osmosis
  • water and mineral ions move into xylem vessels
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6
Q

Explain what is meant by transpiration and th factors affecting transpiration (7) describe how you use a potometer to investigate one of these factors(3)

A

Transpiration
* evaporation of water vapour from inside the leaves and stem of a plant
* through the stomata
* down a water potential gradient
* high temperature increases rate of transpiration
* increasd kinetic energy increase rate of movement of water molecules
* increased air movement increases transpiration
* increasing diffusion gradient
* high humidity decreases rate of transpiration
* decreased diffusion gradient
* high light intenssity increases rate of transpiration
* because of stomatal opening
Potometer
* set up under water/ make sure it is airtight
* air movement can be changed by using a fan
* volume of water measures per unit of time
* to give a close approximation of transpiration rate

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7
Q

State the process by which plant lose water from their leaves (1)

A
  • transpiration
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8
Q

Describe one theory that would explain how water moves up the stem of the leafy shoot (3)

A
  • water lost from leaves / by transpiration
  • causing tension on water molecules
  • cohesive forces between water molecules
  • adhesive forces between water molecules and xylem
  • water molecules pulled ip xylem
  • no mention hydrostatic of root pressure
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9
Q

Describe the role of potasium ions in operation of guard cells closing stomata (1)

A
  • pumped out of guard cells
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10
Q

Describe the role of water potential of cells in operation of guard cells closing stomata (1)

A
  • increased water potential so water moves out
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11
Q

Describe the role of unevenly thickened cell walls in operation of guard cells closing stomata (1)

A
  • decreeased water so decreased volume of cell
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12
Q

How does increased humidity affect rate of transpiration and why (2)

A
  • decrease water loss evaporation
  • reduces concentration gradient between inside and outside leaf
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13
Q

How does increased temperature affect the rate of transpiration and why (2)

A
  • increase rate of water loss
  • greater rate of evaporation from surface of leaf
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14
Q

Describe the uptake of water by plants from the soil into xylem (7) Explain the role of ions in this process (3)

A

Uptake of water
* water absorbed by root hair cells
* water can move through vell walls
* moves across cortex via apoplast route
* can also move across plasma membrane via osmosis
* water moves from cytoplasm of one cell to the next via plasmodesmata
* called the symplast route
* water can also move through cytoplasm and vacoules via cavuolar route
* casparian sstrip
* made of subein
* stops apoplast route and water forced into symplast route
Ions
* ions absorbed into root hair cells by active transport
* ions lower water potential in root hair cells
* an endodermis ions absorbed into cyctoplasm by active transport
* ions travel through periccle into xylem
* lower water potential in xylem
* lower water potential in root hair cell or xylem increase osmotic gradient between soil and cell contents

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15
Q

State what is meant by the term transpiration (2)

A
  • loss of water vapour
  • through stomata
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16
Q

State two practical measures which should be taken when setting up the apparatus to ensure the potometer functions correctly give reasons for your answers (4)

A
  • shoort cut undder watter
  • prevent air bubbles entering
  • shoot with large number of leaves
  • ensure measurable rate of transpiration
  • avoid wetting leaves
  • blocks stomata
  • leave time for apparatus to ettle down
  • allow plant to adapt to new conditions
  • seal joints with caseline
  • prevent air enertering apparatus
  • ensure bubble set art appropriate position
  • enable suitable reading to be taken
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17
Q

Name the original source of energy that moves water through a plant (1)

A
  • sunlight
18
Q

Explain how water moves up the xylem (2)

A
  • molecules of water moving together
  • because of cohesion of molcuels
  • adhesion to walls of xylem walls
  • root pressure forces water upwards
19
Q

Explain how to tell a root diagram apart from the stem diagram (2)

A
  • vascular tissue is a centre and xylem is star shaped
  • no vascular bundles in stem and endodermis not visible in root
20
Q

In rininging experiments why accumulation of sucrose occured (3)

A
  • surcose is produced in photosynthesising leaves
  • sucrose travels in phloem
  • ohloem removed by ringing process
  • sucrose cannot flow to roots
21
Q

Name one type of other organic molecule acumulate with sucrose in rining experiments (1)

A
  • amino acids
  • hormones
22
Q

If gowing points of shoot of the plant are removed there is a greater accumulation of surcose in rining experiment why (2)

A
  • sucrose used for cell wall formation
  • less surcose used by growing areas
  • therefore more will pass down stem
23
Q

Explain fully the likely effect of te removal of the ring of tissue on the concnetration of sucrose below the ring with ringing experiment (3)

A
  • sucrose not replaced from above the ring
  • so concentration decreases
  • as movement towards root continues
  • and sucrose using in respiration / storage
24
Q

Name the tissue strengthened with ligin (1)

A
  • xylem
25
Q

Name tissue that has sieve tubes (1)

A

phloem

26
Q

State the function of sieve tube cells (1)

A
  • translocation of sucrose from source to sink
27
Q

State the function of companion cells (1)

A
  • carry out metabolism to supply sieve cells with ATP
  • contain mitochondira for ATP for active transport
28
Q

Describe two other pathways by which water moves across the root cortex other than vacolar pathway

A
  • apopalst
  • via cell walls
  • symplast
  • via cytoplasm
29
Q

How does casparian strip affect the route water takes into teh stele (1)

A
  • makes water pass through symplast / prevent going through apoplast
30
Q

Give one benefit of transpiration to a plant (1)

A
  • cooling effect
  • maintain transpiration stream
  • required for phtosynthesis
31
Q

Suggest why the end of the shoot should be cut under water before being inseted into potometer (2)

A
  • prevent entry of air into xylem / prevent formation of air bubble in xylem
  • which would break transpiration stream block movement of water
32
Q

State what measurments would habe been made in order to determine the rate of transpiration (2)

A
  • diameter of capillary tube
  • distance travellled by bubble
33
Q

How does sunken stomata able to reduce rate of transpiration (3)

A
  • high humidity in air chamber
  • because water vapour not removed by wind / water vapour trapped
  • this produced a less steep water potential gradient
  • betwee inside of leaf and air chamber inside and outside of stomata
34
Q

Describe and explain two other adaptations except sunken stomata which reduce rae of transpiration for xerophytes (2)

A
  • rolled leafs - reduced surface area exposed for environements
  • clossure of stomata - less openings for water to be lost through
  • hairs 0 increase humidity / traps water vapour
  • thick cuticlee - reduce evaporation from surface of leaf
35
Q

Name two other tyes of cells that are foound in phloem except for sieve tube element and companion cells (2)

A
  • parenchyma
  • phloem fibres
36
Q

Explain how two feature of sieve tube element enable phlowm to carry out its functions (4)

A
  • prescence of sieve plates - permites bidirectional flow
  • few/no organellles - no obstruction to flow of solutes
  • plasmodesmata - allows transport of ATP from companion cell to sieve tube element
37
Q

The mass flow theroy is one explanation to account for the moemvemnt of solutes in the phloem
suggest hy the prescence of large number of mitochondria in companion cells does not ssupport this theory (3)

A
  • mass flow is a passive process
  • down a concentration gradient
  • ATP is not required for a passive process
38
Q

Describe the similarities and differences in the structure and functioning of the arterieies and xylem vessels (10)

A
  • both tubular
  • both movement by mas flow
  • both movement along pressure gradients
  • move in one direction only
  • artery transports blood water transport water
  • moecement liquid pulastile in arteries and smooth in xylem
  • arteries living xylem dead
  • pressure generated by heart in arteries no pump for xylem
  • xylem vesssels contain lignin
  • xylem support function
  • adhesive forces in xylem
  • arteris have elastic tissue
  • arteries recoil
  • smooth endotherlium of artery reduced friction
  • artery walls composed of layers
39
Q

Suggest how Marram grass has adapted its distribution of stomata to conserve water (3)

A
  • lowe density of stomata
  • rolling cause upper epidermis to face inwards
  • no stomata exposed to ssurface
40
Q

State two furtheer structural adaptations shown by marram grass help it to survive in dry conditions (2)

A
  • waxy xuticle on lower surface
  • reduced leaf ssurface area
  • sunken stomata
  • hairs
  • long roots
41
Q

name the source and sink of plant (1)

A
  • source - leaf
  • sink - shoot tip or root
42
Q

Describe and explain the structural adaptations shown by a water lilu and marram grass enable them to survive in environments that differ in terms of water abailability (10)

A

Biology Mark scheme flashcards (14 decks)

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