Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

biolala > Adaptations for transport: Plants C3 > Flashcards

Adaptations for transport: Plants C3 Flashcards

1
Q

write the word equation for photosynthesis

A

carbon dioxide + water to glucose + oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is different about plants’ transport systems compared to animals?

A

they have two separate transport systems instead of transporting water mineral ions and organic molecules together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how is water and mineral ion transported in plants?

A

photosynthetic cells in leaf need water and mineral ions which are available only in soil

so transport of water and mineral ions from roots to leaves is essential

molecules are transported upwards in hollow tubes formed by dead cells called xylem tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how are photosynthates transported?

A

glucose produced during photosynthesis is used to make sucrose and amino acids
these molecules must be moved from the leaves to other organs of the plant
photosynthates are transported upwards and downwards in phloem tissue (bi-directional movement)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

where is the vascular tissue in the leaf?

A

vascular bundle (xylem and phloem) arranged as a vein or midrib

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

where is the vascular tissue found in the stem?

A

vascular bundles arranged around the periphery of the stem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

where is the vascular tissue found in the root?

A

arranged in the centre of the root and together with the endodermis and pericycle is called the stele. there are no vascular bundles in the root

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how are mineral ions like NO3- and water transported to the root?

A

they are actively transported from the soil to the root which lowers the water potential inside the root hair cell so water also enters by osmosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

where is the energy for active transport coming from to aid the transport of mineral ions?

A

oxygen enters the roots from the soil to be used in aerobic respiration, providing ATP for active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

why do waterlogged soils struggle to uptake ions to roots?

A

they lack oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how does the uptake of water and mineral ions happen across the root?

A

travel through root cells of cortex to endodermis down a water potential gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are three routes of the transport of water across the root?

A

symplast
apoplast
vacuolar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

define the apoplast pathway

A

water is taken up by the root hair cell and moves across the cortex by cohesion via the cell walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

define the symplast pathway

A

water moves from the cytoplasm of one cell to the next by osmosis via plasmodesmata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

define the vacuolar pathway

A

water can move via the cytoplasm and vacuoles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe the route of water and mineral ions into the xylem. there are 6 points

A

the cell walls of all endodermal cells contain a Casparian strip made of a waxy substance called suberin that is impermeable to water molecules and mineral ions, meaning the apoplast pathway is blocked at this point

water and mineral ions from the apoplast pathway are forced across the cell membrane into the symplast pathway

active transport is needed to move ions into the cytoplasm of the endodermal cells

mineral ions then diffuse in the pericycle and then into the xylem

therefore the only way that water and mineral ions can pass through the endodermis to the pericycle and into the xylem is by the symplast pathway

water follows by osmosis down a water potential gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

why is the Casparian strip beneficial to the plant?

A

gives plant greater control over which ions can enter xylem and transported to rest of plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how is hydrostatic pressure generated in the root and what effect does it have on water?

A

when water moves from the endodermal cells of the root and into the xylem by osmosis, this generates hydrostatic pressure and forces water a small distance up the xylem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how would cyanide result in a reduction in root pressure? reference the Casparian strip

A

cyanide is a respiratory inhibitor

Casparian strip stops apoplast pathway

movement of ions into the xylem requires active transport

water potential in the xylem is not reduced so there is less root pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

why does the plant need to control the entry of mineral ions into the xylem?

A

some mineral ions are toxic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how does the plant ensure toxic ions can’t enter the cells?

A

Casparian strip forces ions to cross membrane into symplast pathway by active transport

Casparian strip is very impermeable

there are no transport proteins in membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

why do plants need to absorb nitrates from the soil?

A

required for synthesis of amino acids and nucleotides(DNA, RNA, ATP)
nitrogenous base and proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

name some other mineral ions absorbed by plants and state their uses

A

potassium ions for opening stomata
magnesium ions for constituent of chlorophyll
PO4 3- or phosphate ions for synthesis of phospholipids and constituent of nucleotides
calcium is a structural component in plant cell walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

give 2 features of root hair cells that are adaptations for uptake and mineral ions

A

large SA for absorption of water and mineral ions

large numbers of mitochondria to generate ATP for active transport of ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

define transpiration

A

the evaporation of water from inside the leaves through the stomata and into the atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

describe the transpiration stream

A

water is absorbed by the root hair cells by osmosis

water moves through the root tissue into the xylem and is transported up the xylem in the plant stem to the leaf by cohesion

water is transported by osmosis from the xylem in the leaf to the cells of the spongy mesophyll where it evaporates from the surface of the cells into the air spaces

water vapour then diffuses from the air spaces out of the leaf through the stomata down a water potential gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

define cohesion

A

water molecules attracted to each other by hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

define adhesion

A

water molecules are attracted to the hydrophilic lining of the lignified xylem vessel walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

how does water travel up the xylem to the leaves of the plant using cohesion tension theory? (transpiration pull) (give 4 points)

A

as water vapour diffuses out of stomata by transpiration, water molecules are drawn up from behind to replace those lost

water molecules are drawn across leaf and up xylem

this is possible because of cohesion between water molecules due to hydrogen bonds and adhesion between water molecules and xylem vessel walls

this upward movement of water creates tension on xylem vessel walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what are two other processes that help water move up the xylem a small amount?

A

capillarity - forces of adhesion and cohesion allow water molecules to rise up narrow tubes for a short distance which is useful in small plants

root pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

why is capillarity not useful in large trees?

A

it’s useful for small plants and not in larger plants because after a short distance capillary action is opposed by gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what increases the rate of respiration in a plant?

A

any factor that increases water potential gradient between water vapour in leaf and surrounding atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what are four factors the rate of transpiration is increased by?

A

temperature
wind speed
humidity
light intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

explain each of the 4 factors that increase rate of transpiration

A

temperature -
rise in temperature increases the kinetic energy of the water molecules and increases the rate of evaporation and diffusion of the water vapour into the atmosphere
water potential is also lower in high temperatures which increases the water potential gradient

wind speed -
still air results in a layer of water vapour around the stomata of a leaf
this reduces the water potential gradient between the outside and inside of the leaf
air movement blows away the diffusion shell and increases the rate of transpiration from the leaf

humidity -
water potential gradient inside and out of the leaf decreases when there is more water vapour in the atmosphere
usually, there is a steep water potential gradient between the inside of the leaf and the atmosphere as the leaf is saturated with water vapour

light intensity -
light causes stomata to open to allow gas exchange for photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what is a potometer?

A

measures rate of uptake of water by shoot which indicates rate of transpiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

give the labels for the set up of the potometer

A

beaker with water
air bubble in capillary tube
graduated scale in mm along the capillary tube
tap
reservoir of water
bung
plant cutting/leafy shoot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

why is the rate of uptake only an estimate of the transpiration rate?

A

some water is used by the plant as a reactant in photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

give six steps on how to set up the potometer

A

cut leafy shoot underwater to prevent entry of air bubbles into xylem vessels as these would break hydrogen bonds affecting cohesion

completely fill apparatus with water to avoid introducing air bubbles into glassware

fit leafy shoot and seal all joints with Vaseline so apparatus is airtight

pat leaves dry otherwise water potential gradient will be reduced and could affect results

introduce one air bubble into capillary tube (open the tap)

measure distance air bubble moves along scale in a specific time

39
Q

how can you calculate the volume of water taken up from the capillary tube per minute?

A

pi x radius ^2 x height
h = distance moved by bubble
r^2 = internal radius of capillary tube

40
Q

how could you improve the reliability of the data collected in the potometer experiment?

A

repeat 3x to allow calculation of a mean

41
Q

what can you calculate from potometer data after working out the mean?

A

standard deviation

42
Q

what is standard deviation?

A

measure of the spread of a set of data

indication of amount of variation or dispersion in data set

43
Q

what does a low standard deviation indicate and what does a high standard deviation indicate?

A

low -
the values are close to the mean so therefore are more consistent and more reliable
‘thin’ curve
high -
data values are further from the mean so spread out over a wider range, meaning they are less consistent and less reliable
‘fat’ curve

44
Q

what is the formula of standard deviation? what does each symbol mean?

45
Q

how do you calculate standard deviation? give 6 steps

A

1 - calculate mean for the data set
2 - subtract the mean from each value
3 - square each answer
4 - add up all the squares
5 - divide this total by the number of pieces of data minus 1
6 - find the square root of that value

46
Q

what are the 4 different types of cell that a xylem is composed of?

A

vessels
tracheids
fibres
xylem parenchyma

47
Q

what is the role of vessels in the xylem tissue?

A

the main cells that conduct water

48
Q

what are the vessels in the xylem tissue made up of?

A

continuous column of dead cells arranged end to end with completely dissolved cross/end-walls to form long, hollow tubes that transport water from roots to leaves

their walls are thickened with lignin which is impermeable to water and strengthens and supports the plants so the vessel doesn’t collapse under pressure

49
Q

what is the function of tracheids in xylem tissue?

A

they also conduct water but are less efficient than vessels

50
Q

what are tracheids made of in the xylem tissue?

A

they are similar to vessels but are more elongated with tapering ends
cell walls are also thickened and impregnated with lignin

51
Q

how are the pits efficient in tracheids and vessels in xylem tissue?

A

they both have pits in their side walls
in vessels they allow movement of water between adjacent vessels
in tracheids they are involved in movement of water to nearby living tissue

52
Q

what is the role of fibres in the xylem tissue?

A

no role in transport and is only there for support only

53
Q

what is the role of xylem parenchyma in xylem tissue?

A

they are living cells and are packing tissue

54
Q

why is it important that vessel walls are impermeable to water and solutes?

A

so that xylem is not leaky and water keeps moving upwards to the leaves in one unbroken column

55
Q

why is lignin being hydrophilic important to xylem function?

A

water molecules are attracted to the walls of the xylem vessels supporting adhesion
it also strengthens and supports the plant

56
Q

what does phloem transport?

A

amino acids and sucrose

57
Q

what 4 types of cell is phloem tissue made of?

A

sieve tubes
companion cells
phloem fibres
phloem parenchyma

58
Q

what is the function of sieve tubes in the phloem tissue?

A

transport sucrose and amino acids up/down plant stem

have few organelles so more space for transport of solutes

59
Q

what are sieve tubes made of in the phloem tissue?

A

they are formed from cells called sieve elements placed end to end
the thin cellulose wall at the ends of these cells is perforated to form sieve plates that allow the cytoplasm from one cell to run into an adjacent cell and allow passage of dissolved solutes

60
Q

what is the role of companion cells in the phloem tissue? why are they important?

A

connected to sieve tubes via plasmodesmata

don’t transport organic compounds but have a nucleus and provide ATP for active transport of sugars into/out of sieve tubes

important since sieve tubes cells lose their nucleus and other organelles as they mature

61
Q

what is the role of phloem fibres in phloem tissue?

A

for support

62
Q

what is the role of phloem parenchyma in phloem tissue?

A

they are living tissue

63
Q

what runs through the sieve plates in phloem tissue?

A

phloem protein or filaments in the cytoplasm run through the sieve plates
smaller strands of cytoplasm run through the side walls of sieve tube cells into adjacent companion cells through the plasmodesmata

64
Q

define translocation

A

the transport of soluble organic materials produced by photosynthesis in the phloem

65
Q

what is the liquid inside the phloem called?

A

sap

66
Q

what is the movement of molecules called in phloem?

A

bi-directional

67
Q

what is the source in a plant?

A

the region where the products of photosynthesis is produced and exported

68
Q

what is the sink in a plant?

A

the region where products of photosynthesis are stored or used for growth

69
Q

give an example of a source

A

leaf

70
Q

give examples of sinks

A

root, shoot tips, flowers, fruit, seeds

71
Q

describe the ‘ringing experiment’ in three points used to provide evidence for translocation in phloem

A

remove a ring of outer bark tissue from woody stem to remove phloem

analysis of phloem contents above and below ring shows organic compounds can’t be transported past removed bark region

buldging due to accumulated phloem sap that can’t move down further

72
Q

what 2 things does the ‘ringing experiment’ show?

A

phloem is around on outside just under bark

transport of organic compounds can be downwards

73
Q

describe the aphid experiment to provide evidence for translocation in the phloem in 4 points and explain why it’s more accurate than a human using a syringe

A

aphids can be used to collect contents of individual phloem sieve tube cells

have specialised mouthparts called stylets which are used to penetrate sieve tubes to feed on sugary sap inside

if anaesthetised with co2, stylet can be cut off and left in stem which means pure phloem sap collected through stylet for analysis

more accurate than human with a syringe as aphid’s enzymes ensure that stylet doesn’t get blocked

74
Q

describe radioisotope labelling used to provide evidence for translocation in phloem in 4 points

A

one leaf of a plant is supplied with radioactive 14co2

after 20 minutes, plant placed on photographic film and dark areas on film show areas containing radioactivity

results show that radioactive carbon is fixed into sugar at source and then translocated to sink parts of plant (shown as dark regions)

shows sugar is transported bidirectionally since radioactivity seen in aerial parts of plant as well as roots

75
Q

which parts of the plant contain the most radioactivity and explain your answer using source and sink?

A

leaf A which is the source, roots, shoot tips, young leaves

sucrose is produced at the source and is transported to sink regions that cannot photosynthesis or are actively growing

76
Q

what is the mass flow hypothesis?

A

it is the main theory to explain translocation

sugars flow passively from areas of high concentration in the leaf (source) to areas of low concentration (sinks like growing tissue) down a pressure gradient

77
Q

how does the mass flow theory work?

A

sucrose made in photosynthesis is loaded by active transport into the sieve tubes, using ATP

water enters the sieve tubes along a water potential gradient by osmosis

the pressure in the sieve tubes increases and the sucrose moved down a pressure gradient through the phloem towards the sinks

sucrose is unloaded by active transport into the cells at the sinks

water moves by osmosis out of the phloem as the sucrose is removed and the pressure in the phloem tissue becomes lower at the sink

78
Q

what does the mass flow theory not explain?

A

the observations that sucrose is transported in sieve tubes at a rate of 25 - 100 cm per hour even though diffusion alone would give a transport rate of 0.2mm per day

79
Q

what are the arguments against the mass flow theory?

A

no explanation of sieve plates which seem to act as barriers to flow

sucrose and amino acids have been observed moving a different rates and in different directions

sieve tubes have a high rate of ATP consumption, and translocation is slowed or stopped if respiratory inhibitors such as cyanide are added

the companion cells are found all along the sieve tubes not just in the sources and sinks and contain numerous mitochondria for the production of ATP so if companion cells purely load and unload photosynthates from the sieve tubes they would not be needed anywhere but the sources and sinks

therefore there must be an active process within the sieve tubes that maybe involved

80
Q

what are some alternative theories to the mass flow theory?

A

streaming in the cytoplasm of sieve tubes could be responsible for bi-directional movements

protein filaments have been observed passing through the sieve pores suggesting different solutes are transported by different filaments

81
Q

what are mesophytes?

A

most of the plants in temperate regions and most crop plants are mesophytes

82
Q

what do mesophytes grow best in?

A

well-drained soils and moderately dry air

83
Q

what are three plant behaviours that allow mesophytes to survive at unfavourable times of the year?

A

deciduous trees shed leaves in autumn to survive unfavourable conditions in winter and new leaves grow in spring

bulbs and corms, which are storage organs, are produced by non-woody plants to survive underground over winter

annual plants produce seeds and die in the same year as seeds survive winter frost and germinate the next spring when conditions are more favourable

84
Q

what are hydrophytes?

A

water plants that live submerged/partially submerged in water

85
Q

give 5 features of a hydrophyte and their explanations

A

stomata on the upper epidermis -
to allow gas exchange with the air above

large air spaces -
to provide buoyancy for the leaves and act as a reservoir of oxygen and co2

thin waxy cuticle -
no need to reduce water loss as they live on/in water

xylem tissues poorly developed -
no need to transport large quantities of water as plant is aquatic

little lignin in plant tissue -
water is a supportive medium and so little lignin is required to support the xylem tissue

86
Q

what are xerophytes?

A

these plants are adapted to conditions of low water availability and live in hot desert conditions/cold regions where soil is frozen/exposed windy locations

87
Q

what is an example of a xerophyte?

A

marram grass

88
Q

give 5 features of marram grass and their explanations

A

sunken stomata in pits -
water vapour trapped in the pits decreases the water potential gradient between the inside and outside of the leaf so less water is lost by transpiration

hairs on leaf surface -
water vapour trapped between the hairs decreases the water potential gradient between inside and outside of the leaf so less water is lost by transpiration

thick waxy cuticle -
reduces water loss from the epidermis

rolled leaves -
stomata less exposed to the atmosphere
water vapour trapped decreases the water potential gradient between inside and outside of the leaf so less water is lost by transpiration

reduced leaf size/spines -
reduces the surface area from which transpiration can occur

89
Q

describe the xerophytic adaptations of cacti

A

store water in succulent stems

leaves are reduced to spines to reduce surface area for transpiration

thick waxy cuticle

shallow spreading roots/long deep roots to maximise water absorption from soil

90
Q

why do pine trees have needle-like leaves?

A

to greatly reduce surface area of leaf available for water loss by transpiration

91
Q

why do many xerophytes open stomata at night and close them during the day?

A

to conserve water

92
Q

label the different structures present in a root

A

stele, phloem, xylem, endodermis, pericycle, cortex, epidermic, root hair

93
Q

label the different structures present in a stem

A

phloem, xylem, vascular cambium which is the border between the xylem and phloem, pith, cortex

94
Q

label the different structures present in a leaf

A

waxy cuticle
upper epidermis
palisade mesophyll
spongy mesophyll
vein-like vascular bundle containing xylem and phloem
lower epidermis
stomata and guard cells

biolala (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions