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Biology > mr Allsop- transport in plants > Flashcards

mr Allsop- transport in plants Flashcards

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1
Q

where does oxygen enter

A

stomata

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2
Q

what does the xylem transport

A

water and mineral ions from roots

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3
Q

what is lignification

A

death of xylem cells (loss of cytoplasm, organelles) so left with a hallow structure to transport water- has to die to function.

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4
Q

what’s lignin

A

waterproofs the xylem and provides reinforcement so they don’t collapse under the transpiration pull.

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5
Q

what are boarded pits

A

where lignification hasn’t taken place, so no lignin which means its not waterproof so water leaks out.

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6
Q

what is capillary action

A

water molecules held together by hydrogen bonds (cohesion) and slightly stick to the side of xylem (adhesion) . these forces pull water up as mass flow.

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7
Q

whats parenchyma

A

packing tissue, fills gap between xylem and phloem tissue.

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8
Q

what does the phloem transport

A

sucrose which is a less soluble version of glucose for transportation and then dissolves in water to form sap
amino acids

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9
Q

what are amino acids and sucrose known as

A

assimilates which is made by the plant (source) to then be absorbed by the plant. (sink)

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10
Q

what are sieve tube elements

A

lined up end to end, no nucleus, little cytoplasm to leave space for sap to move along by mass flow.

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11
Q

what are sieve plates

A

allow sap to move from one sieve tube element to another.

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12
Q

what are companion cells

A

release energy to load assimilates into sieve tubes.

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13
Q

what is the source

A

has dense cytoplasm with lots of mitochondria for aerobic respiration that produces ATP to load assimilates.

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14
Q

what is the sink

A

where assimilates are deposited.

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15
Q

what is plasmodesmata

A

thin strands of cytoplasm that link adjacent cells ( companion cells) for assimilates to flow through sieve tube element’s.

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16
Q

what is translocation

A

transports assimilates.

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17
Q

how are root hair cells specialised

A

large surface area
lack of chloroplasts- underground
large number of mitochondria for active transport

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18
Q

what is the epidermis

A

outermost cell layer of plant where root hair cells are located.

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19
Q

what is the root cortex

A

series of plant cells on the outer layer under epidermis

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20
Q

what’s the symplast pathway

A

water and mineral ions moving through cytoplasm via plasmodesmata

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21
Q

what’s the vacuolar pathway

A

water and mineral ions go through vacuole and then plasmodesmata.

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22
Q

what is the apoplast pathway

A

hallow structure in cell wall where charged ions can pass through without interaction with hydrophobic core.

23
Q

what is the endodermis

A

next layer
cylinder of cells that forms the final boundary between the cortex and the inner region of a plant.

24
Q

what’s suberin

A

waterproof, impermeable substance in the walls of root endodermal cell.
these bind together to form casparian strip

25
Q

what is the casparian strip

A

blocks apoplast pathway so toxins don’t enter without being selected by plasma membrane through hydrophobic core, so water is forced into the cytoplasm in the plasmodesmata, this then pumps mineral ions into the medulla lowering the water potential so water then follows but can’t leave because of the casparian strip.

26
Q

what is transpiration pull

A

water moving up the xylem because of water being lost at leaf.

27
Q

what is cohesion

A

the slightly negative oxygen is attracted to the slightly positive hydrogen causing water to move as a column

28
Q

what is adhesion

A

water attracts to walls of xylem to pull it up

29
Q

what is capillary action

A

water moves against gravity because xylem is very narrow so strong forces pull upwards.

30
Q

what is the mibrid

A

middle of vein

31
Q

what is the petiole

A

stem

32
Q

what is the blade

A

in between veins

33
Q

what is the sub-stomatal air space

A

space above stomata

34
Q

what are the 3 uses of water in leaf

A

photosynthesis in palisade mesophyll
osmosis in guard cells to make them turgid
move into other cells

35
Q

how does water move from spongy mesophyll

A

turns into water vapour in air pockets this creates a water potential gradient as inside air pockets it is a high water potential compared to outside.

36
Q

what is the source of a cell

A

where assimilates are loaded which requires companion cells because its an active transport.

37
Q

what is a co-transporter protein

A

two molecules move across membrane.

38
Q

what is translocation

A

the mass flow of assimilates down the hydrostatic pressure gradient from source to sink.

39
Q

how does translocation work

A

hydrolyse atp so energy is released pumping h+ ions outside of companion cells
co-transporter pump h+ and sucrose ( or amino acids) back into companion cell. sucrose is against concentration gradient as there is already a high conc of sucrose in cell but H+ goes along conc gradient.
sucrose now in sieve tubes after going through plasmodesmata this lowers water potential so sap is created by water entering by osmosis.
source has high hydrostatic pressure so sink has low because there is a pressure gradient.

40
Q

what is hydrostatic pressure

A

pressure exerted by fluid on its container at a given point.

41
Q

example of a source, sink, storage organ

A

source- leaves
sink- bud, flower, fruits, roots
sink+ source- storage organ

42
Q

how do guard cells open and close stomata

A

carrier proteins in membrane actively move solutes to guard cells so water moves in to guard cell down conc gradient by osmosis
when water moves out the guard cells go flacid closing stomata.

43
Q

what does A-symmetric shape mean

A

inner wall of guard cell is thicker and outer walls thinner so bend causing this shape ()

44
Q

how does air movement increase transpiration rate

A

h20 diffuses out of the stomata accumulating in a layer of air which would create high water potential at stomata but wind will blow this h20 lowering gradient so water moves up.

45
Q

how does humidity lower transpiration rate

A

not much transpiration with high humidity as there is a high water potential at stomata so no gradient.

46
Q

how does temperature affect transpiration

A

increase temp, more kinetic energy so water vapour molecules have to move faster out of plants so transpiration happens because low water potential outside.

47
Q

how does light intensity affect transpiration

A

stomata open when its light so more h20 molecules diffuses out

48
Q

how does soil water availability affect transpiration

A

lack of water puts plant under ‘water stress’.
so water will be conserved and rate of transpiration will decrease

49
Q

what is a potometer

A

measures water uptake ( transpiration)
cut plant at angle under water to prevent air bubbles.
scale+ air bubble
leaves dry
all joints secured by waterproof wax.
more evaporation- faster transpiration- bubble speed increases.

50
Q

what are examples of xerophytes

A

marram grass and cacti

51
Q

adaptations of marram grass

A

adapted to dry, arid conditions that are very windy and salty.
roots 15-20 m long
leaves rolled up which traps humid air so high water potential meaning transpiration doesn’t occur.
waxy cuticle
stomata on inner underside of plant in pits to stop water being blown away from sacks so it keeps high water potential.
very dense mesophyll so less space for water to pass through.

52
Q

adaptations of cacti

A

waxy cuticle
succulents- thick stem so water can expand
leaves are now spines so reduced surface area
wide spread roots.

53
Q

adaptations of water lilies which are hydrophytes

A

lots of air space in mesophyll to allow for buoyancy to keep it afloat
stomata on upper epidermis- gas exchange easier air is more abundant at the top.
stem has air space to allow oxygen to quickly diffuse through
hydathodes- secretes water to lower water potential generating transpiration pull .

Biology (15 decks)

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