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Biology New > 3.4.2.1: Xylem & transpiration > Flashcards

3.4.2.1: Xylem & transpiration Flashcards

1
Q

what do xylem transport

A

water and mineral ions

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2
Q

what are packing cells

A

cells that fill up space

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3
Q

what does organic mean

A

carbon based

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4
Q

what are andeosperms

A

flowering plants

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5
Q

describe the structure of xylem tissue

A

xylem vessel, lignified wall of xylem vessel, fibre, tracheid, parenchyma cell

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6
Q

which of these have a nucleus in xylem tissue: tracheids, fibre, xylem vessel, parenchyma cell

A

parenchyma cell and so tracheids, xylem vessels and fibre are dead

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7
Q

What is the main feature of lignin in xylem tissue

A

they are impermeable to anything and kill anything in the cell

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8
Q

what advantages does lignin give to xylem and why

A

lignin lines the xylem vessel elements, killing anything in the cell (tracheids, xylem vessels, fibres), and so the cell is hollow for water to move through.
Lignin also gives strength by preventing the xylem vessel elements from collapsing when water is moving through, as lignin is impermeable to water

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9
Q

is there lignification in the vessel element

A

yes

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10
Q

is there lignification in the tracheid

A

yes

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11
Q

is there lignification in the fibre

A

yes

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12
Q

is there lignification in the parenchyma

A

no, cellulose

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13
Q

are vessel elements living

A

no

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14
Q

are tracheids living

A

no

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15
Q

are fibre living

A

no

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16
Q

are parenchyma living

A

yes

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17
Q

describe the structure of the vessel elements in xylem tissue

A

stacked end to end, end walls disintegrate to form hollow tubes

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18
Q

describe the structure of a tracheid in xylem tissue

A

stacked end to end, slanted end walls

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19
Q

what is the function of the vessel element in xylem tissue

A

transport of water and mineral ions

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20
Q

what is the function of the tracheid in xylem tissue

A

transport of water and mineral ions

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21
Q

what is the function of the fibre in xylem tissue

A

provide mechanical support for tissue

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22
Q

what is the function of the parenchyma in xylem tissue

A

packing cell between vessel elements

23
Q

what is meant by the term transpiration

A

evaporation of water vapour

24
Q

how does lignin appear on xylem tissue and what does it allow the xylem tissue to do

A

lignin is in rings which allows the cells to stretch and grow longer

25
Q

Describe very simply the direction that water vapour diffuses/evaporates in a leaf, in relation to the mesophyll cells, air spaces and the stomata

A

water vapour diffuses out of stomata (down water potential gradient). This water is replaced by water vapour that evaporates out of the mesophyll cells into air spaces

26
Q

how much of the uptake of water is used and is transpired, and also, what is the role of each

A

1% is used for photosynthesis and maintaining turgor
99% is transpired for a cooling effect and to bring in mineral ions through roots

27
Q

what is the transpiration stream and where is it in a plant

A

the transpiration stream is a single continuous column of water from the roots to the leaves

28
Q

How does the transpiration stream in a plant work

A

transport of water up xylem into leaf, evaporation into water vapour and diffusion out of stomata, pull of water out of the leaf causes tension on water

29
Q

what does the vascular bundle consist of

A

phloem, cambium, xylem

30
Q

where are the vascular bundles positioned in a stem

A

around the periphery of the stem

31
Q

why are the vascular bundles positioned around the periphery of the stem

A

wind imposes bending strain on the stem, and so the vascular bundles provide strength and structure by being around the periphery of the stem

32
Q

where are the vascular bundles positioned in a root

A

straight down the middle

33
Q

why are the vascular bundles positioned straight down the middle of a root

A

gravity imposes strain on the root and so the vascular bundles provide strength and structure by being straight down the middle of the root

34
Q

Describe the structure of a stem and state what the parenchyma cells are

A

epidermis, cortex - parenchyma cell, vascular bundle (phloem, cambium, xylem), pith - parenchyma cells

35
Q

describe the structure of a root and state what the parenchyma cells are

A

exodermis, epidermis, cortex - parenchyma cell, vascular bundle (phloem, cambium, xylem), pericycle, endodermis

36
Q

by what process does water move up the stem

A

cohesion-tension theory

37
Q

state the property of the xylem vessels that ensures water can be drawn up them more than 10m

A

xylem vessels are very narrow causing the water to form a single continuous line

38
Q

what is the meaning of cohesion in terms of the cohesion-tension theory of the movement of water through the xylem and what does it result in

A

water molecules tend to attract to each other due to their hydrogen bonding which results in a continuous column of water

39
Q

what is the meaning of tension in terms of the cohesion-tension theory of the movement of water through the xylem

A

transpiration of water out of the leaf creates a force that pulls the column of water up, stretching it and so it is under tension

40
Q

describe and explain the property of water molecules that enables them to exhibit cohesion

A

they are polar molecules, hydrogen atoms have a partial positive charge and the oxygen atom has a partial negative charge, the opposite partial charges are attracted to each other and so causing attractions between water molecules which is called cohesion

41
Q

explain two advantages of transpiration for the plant

A

1 - transports mineral ions around the plant
2 - Evaporation of the water from the leaves has a cooling effect which can reduce possibility of leaves overheating and enzymes being denatured

42
Q

explain one disadvantage of transpiration for the plant

A

causes water loss which is necessary for the plant to function

43
Q

Is the uptake of mineral ions by plant roots passive or active?
explain why

A

active transport as there is a much greater ion concentration in the root than in the soil, so uptake is against the concentration gradient.
Also, when respiratory inhibitors are added to the roots, uptake rate is reduced

44
Q

Describe how root hair cells are adapted for efficient uptake of ions

A

large SA:Vol
lots of mitochondria (and so lots of ATP for active transport)
lots of carrier proteins (Active transport)
thin cell wall

45
Q

Describe the structure of a root hair cell

A

nucleus, vacuole, cytoplasm, cell wall

46
Q

how is a potometer set up?

A

entire thing should be set up underwater, should cut the leafy shoot and attach it underwater, BUT leaves need to stay dry - so water doesn’t block any stomata pores in leaf), cover any joints with vaseline to make them airtight

47
Q

what measurements need to be taken when using a potometer to calculate the rate of water uptake

A

distance that the air bubble travels in mm, time it takes to travel that distance in s, diameter of capillary tube in mm

48
Q

how would you calculate the rate of water uptake by using a potometer

A

speed of air bubble movement x cross sectional area of capillary tube = rate of water uptake

49
Q

what 4 factors affect transpiration rate

A

light intensity, temperature, humidity, air movement

50
Q

how does an increase in light intensity affect the rate of transpiration and explain why

A

increases the rate of transpiration, because:
1 - stimulates stomatal opening for gas exchange for photosynthesis
2 - increased number of open stomata increases SA for diffusion of water vapour

51
Q

how does an increase in temperature affect the rate of transpiration and explain why

A

increases the rate of transpiration, because:
1 - increased evaporation out of mesophyll cells
2 - air spaces in leaf become saturated with water vapour
3 - increased diffusion gradient to outside of leaf

52
Q

how does an increase in humidity affect the rate of transpiration and explain why

A

decreases the rate of transpiration, because:
1 - increased number of water molecules in air surrounding stomatal openings
2 - reduced diffusion gradient to outside of leaf

53
Q

how does an increase in air movement affect the rate of transpiration and explain why

A

increases the rate of transpiration, because:
1 - saturated air moves away from leaf surface
2 - increases diffusion gradient to outside of leaf

Biology New (46 decks)

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