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Bio A Levels Unit 2 Linton/Jones re-run > Unit 2.3 Plant Transport > Flashcards

Unit 2.3 Plant Transport Flashcards

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Biology 101 flashcards
1
Q

What process used to take mineral ions from soil in plants?

A

Active transport

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2
Q

How can active transport occur?

A

Need ATP

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3
Q

How can the plant produce ATP?

A

Respiration in mitochondria

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4
Q

What process used to move water in plants?

A

Osmosis

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5
Q

Quickly define osmosis?

A
  • Movement of water molecules
  • Down a water pot. gradient
  • Through a selectively permeable membrane
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6
Q

How to decrease water potential?

A

Increase conc. of solutes (mineral ions in cytoplasm)

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7
Q

How plant can photosynthesise?

A

Stomata pores open,
allowing gas exchange

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8
Q

Quick equation of photosynthesis?

A

CO2 + H2O -> Glucose + O2
-> = light energy

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9
Q

What consists of the vascular system?

A

Xylem + Phloem

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10
Q

Why would plants have a vascular system?

A

Idk?? Height of plants can pose problems (constant supply)
bro idk….

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11
Q

Without vascular tissues in plants = ?

A
  • Diffusion would be too slow
  • Diffusion pathway would be too long
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12
Q

Define xylem?

A
  • System of vessels connected end to end
  • To form a non-living, continuous hollow tubes
  • That transport water and minerals
  • UP the plant [TRANSPIRATION]
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13
Q

Define phloem?

A
  • Living tissue which consists of cells
  • Called sieve tubes & companion cells
  • That transport organic substances (e.g. sucrose)
  • Made by photosynthesis
  • UP & DOWN the plant [TRANSLOCATION]
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14
Q

Define mass flow?

A
  • Bulk movement of substances
  • From one area to another area
  • Along pressure gradients
  • Due to pressure differences
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15
Q

Look in book for T.S. root diagram

A

:<

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16
Q

How a root hair cell adapted for absorption?
(4 things)

A
  • Large surface area
  • Many mitochondria
  • Many carrier proteins
  • Thin cell wall (shorter distance for diffusion)
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17
Q

Look in book for T.S. stem diagram

A

,:<

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18
Q

Look in book for T.S. leaf diagram

A

,’:<

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19
Q

Step 1 of water transport in plants?

A
  • Mineral ions transported into root hair cells
  • By active transport
  • Decreases water pot. in root hair cells
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20
Q

Step 2 of water transport in plants?

A
  • Water moves into root hairs
  • Down the water pot. gradient
  • By osmosis
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21
Q

Step 3 of water transport in plants?

A
  • Water enters xylem of root
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22
Q

Step 4 of water transport in plants?

A
  • Water moves up xylem of stem
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23
Q

Step 5 of water transport in plants?

A
  • Water moves from leaf xylem
  • To mesophyll cells
  • In leaf
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24
Q

Step 6 of water transport in plants?

A
  • Evaporation of water into air spaces
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25
Q

Step 7 of water transport in plants?

A
  • Diffusion of water vapour
  • Through stomata
  • Into air
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26
Q

Oh and make sure u look in book for diagram of water transport in plants

A

’:|

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27
Q

What is the transpiration stream?

A

Movement of water across the root ig?

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28
Q

After water absorbed into root hair cell, why water continue journey across root cortex?

A
  • Water pot. in xylem lower than water pot. in
  • Root hairs and cells in between
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29
Q

3 ways of transpiration stream?

A
  1. Apoplast pathway
  2. Symplast pathway
  3. Vacuolar pathway
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30
Q

Make sure u look in book for diagram of them pathways

A

¬.¬

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31
Q

Brief info of apoplast pathway?

A
  • Mass flow through plant cell walls
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32
Q

Brief info of symplast pathway?

A
  • Osmosis through cytoplasm & plasmodesmata
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33
Q

Brief info of vacuolar pathway?

A
  • Similar to symplast, swap cytoplasm with vacuoles
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34
Q

Which transpiration stream pathway faster and why?

A
  • Apoplast pathway
  • Less resistance
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35
Q

Look in book for that casparian strip thingy

A

¬>¬

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36
Q

Define protoplast?

A

Living part of a cell e.g. nucleus

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37
Q

Why substances move across endodermis into the xylem by symplast route only?

(7 steps D:)

A
  • Apoplast pathway blocked
  • By casparian strip
  • Made of waterproof suberin
  • So water moves out of apoplast pathway
  • And into symplast pathway.
  • Ensures water can’t leave xylem
  • By apoplast pathway
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38
Q

Endodermal cells move minerals by active transport from the cortex into the xylem

How does this affect the water pot. in xylem?

A
  • Lowers water pot. in xylem
  • So water moved from cortex to xylem by osmosis
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39
Q

Step 1 of water transport through leaves?

A
  • Water enters xylem vessels
  • Of the leaf from the stem xylem
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40
Q

Step 2 of water transport through leaves?

A
  • Water leaves xylem
  • Enters mesophyll cells by osmosis
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41
Q

Step 3 of water transport through leaves?

A
  • Water evaporates from cell walls
  • Of mesophyll cells
  • Collects in the air spaces as
  • Water vapour
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42
Q

Step 4 of water transport through leaves?

A
  • As water vapour collects here
  • Water vapour pot. in air spaces
  • Increases
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43
Q

Step 5 of water transport through leaves?

A
  • When water vapour pot. in
  • air spaces = higher than outside
  • Water vapour diffuses
  • out of leaf via
  • Open stomata
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44
Q

Step 6 of water transport through leaves?

A
  • Air movements carry water vapour
  • Away from leaf surface
  • Maintains water vapour pot. gradient
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45
Q

The main force that pulls water up the xylem is evaporation of water from leaves - a process called….?

A

Transpiration

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46
Q

What allows the column of water to be pulled up to the stem?

A
  • Tension to the column of water
  • During transpiration
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47
Q

What are the 3 theories regarding of the movement of water up the stem in the xylem?

A
  1. Root pressure theory
  2. Capillarity/Adhesion theory
  3. Cohesion-tension theory
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48
Q

Explain root pressure theory
(6 things)

A
  • Endodermis actively transports mineral ions into xylem vessels
  • Water pot. in xylem decreased
  • Water moves into xylem by osmosis
  • Creates hydrostatic pressure
  • Thus water pushed up the xylem of the root then stem
  • Root pressure only operates over short distances
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49
Q

Explain capillarity/adhesion theory
(6 things)

A
  • Xylem vessels narrow
  • And have hydrophilic lining
  • Water molecules attracted & adhere to the walls
  • Causes water move up vessel by capillary action (capillarity)
  • Operates over short distances
  • Makes small contribution to water movement in plants (less than a few cm’s high)
50
Q

What is cohesion-tension theory?

A

It’s the main mechanism of movement of water + involves transpiration of water from leaf

51
Q

Step 1 of cohesion-tension theory?

A
  1. Water evaporates from spongy mesophyll cells
    - Into air spaces & diffuses out of stomata
    - Down water pot. gradient
52
Q

Step 2 of cohesion-tension theory?

A
  1. Creates water pot. across leaf
    - From higher water pot. in xylem
    - To lower water pot. in air spaces
53
Q

Step 3 of cohesion-tension theory?

A
  1. Water molecules = cohesive
    (Forms hydrogen bonds between each other and stick)
    - As water drawn out from top of xylem
    - More water pulled up xylem to replace it
54
Q

Step 4 of cohesion-tension theory?

A
  1. Pulling action of transpiration stretches water column
    - In xylem
    - So it’s under tension
    - Means whole continuous column of water in xylem
    - , From leaves down to the roots,
    - Gets pulled upwards
55
Q

Step 5 of cohesion-tension theory?

A
  1. Water molecules also attracted to hydrophilic lining
    - Of xylem vessels
    - This is adhesion
    - Contributes to water movement
    - Up the xylem
56
Q

How diameter of a tree trunk smaller in middle of the day than in morning & evening?
(3 things)

A
  • Increased transpiration during noon
  • Produces negative pressure
  • Reduces diameter
57
Q

Why should ya cut stems of flowers… and place them in a vase all under water?

A
  • Stop air bubbles getting into xylem
  • And breaking water column
58
Q

Look in book for structure of xylem

A

O_o

59
Q

Look in book for T.S. & L.S. of xylem vessel

A

o-o’

60
Q

Why do lignin form patterns in the cell wall?
(3 things)

A
  • Spiral patterns allows flexibility
  • Whilst still preventing
  • Collapse or breakage
61
Q

No cell contents

(How xylem’s structure is related to its function)

A
  • Hollow lumen
  • Less resistance to water flow
62
Q

Lignin in cell walls

(How xylem’s structure is related to its function)

A
  • Supports walls
  • Prevents collapse due to tension in xylem
  • Hydrophilic lining allows adhesion
63
Q

Pits in cell walls

(How xylem’s structure is related to its function)

A
  • Allows lateral movement of water
  • Out of xylem to other xylem
    -, Phloem or surrounding cells
64
Q

Narrow tubes

(How xylem’s structure is related to its function)

A
  • Capillary action more effective
  • Water column doesn’t break easily
65
Q

Elongated cells, no end walls

(How xylem’s structure is related to its function)

A
  • Continuous column of water
  • For free flow
  • Less resistance
66
Q

Wide lumen

(How xylem’s structure is related to its function)

A
  • Ease of flow of water
67
Q

Uhhhhh, we may have an issue for the transpiration part of the booklet

A

;-;

68
Q

Why is transpiration unavoidable?

A
  • Allow CO2 into leaves for photosynthesis
69
Q

Features of mesophytes?
(4 things)

A
  • Stomata closed at night
  • Deciduous plant (loses leaves in winter when ground may be frozen due to less water available)
  • Production of dormant seeds (survives over winter)
  • Aerial parts dying off leaving bulbs surviving underground
70
Q

What are xerophytes?
(‘xero’ = dry ‘phyte’ = plant)

A

Plants well adapted to live in very dry/arid conditions

71
Q

Look in book for diagrams of a buncha xerophytes

A

O_O_O_O

72
Q

Stomata are sunken in pits

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Traps water vapour close to stomata
  • Creating high humidity in air chambers
  • Reduces steepness of water vapour pot. gradient
  • Between inside of leaf and air chamber
73
Q

Hairs/trichomes

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Trap water vapour
  • Reduce water pot. gradient
74
Q

Rolled leaves

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Reduces surface area exposed to environment
  • e.g. stomata ‘inside’
  • Reduces air movements past lower epidermis
  • Same as hairs/trichomes
75
Q

Few stomata

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Reduces water loss
  • Cuz less pores
  • Less water escaping
76
Q

Thick waxy cuticle

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Waterproof
  • Reduces evaporation of water
  • From epidermis
77
Q

Smaller/fewer leaves or needle-like leaves

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Fewer stomata
  • Less surface area
78
Q

Stoma shut in day

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Little/no water vapour loss
  • From stomata of leaves
  • During day
79
Q

Long roots/spread out roots

(How xerophytes adapted to reduce water loss by transpiration)

A
  1. To get water deep underground
  2. To catch rainfall
80
Q

Low water pot. inside cells (by maintaining high salt conc. in cells)

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Reduces evaporation
  • And diffusion of water
  • Cuz gradient reduced
81
Q

Stiff sclerenchyma fibres in leaf

(How xerophytes adapted to reduce water loss by transpiration)

A
  • Maintains shape of leaves
  • If cells get plasmolysed/flaccid
82
Q

What are hydrophytes?

A

Plants that grow partially/wholly submerged in water
e.g. water lily

83
Q

Look in book for diagrams of hydrophytes

A

0_0

84
Q

No lignified support tissues

(Adaptations of hydrophytes features)

A
  • Water provides support
  • So no need
85
Q

Xylem poorly developed

(Adaptations of hydrophytes features)

A
  • Surrounded by water
  • Don’t need transport tissues
86
Q

Leaves have little cuticle

(Adaptations of hydrophytes features)

A
  • No need to prevent water loss
87
Q

Stomata on upper surface

(Adaptations of hydrophytes features)

A
  • Upper surface exposed to air
88
Q

Stems and leaves have large air spaces

(Adaptations of hydrophytes features)

A
  • Provide buoyancy (float on water)
89
Q

Look in book for L.S. & T.S. Phloem diagrams

A

T-T

90
Q

Explain sieve tubes’ lack of cell contents
(no nucleus/gorgi/tonoplast/ribosomes)

A

No obstruction to flow

91
Q

Why companion cells of many mitochondria?
(3 things)

A
  • Producing high level of ATP
  • Active transport involved in
  • Movement of substances
92
Q

Look in book for the labelling of phloem

A

T_T_T

93
Q

Function of phloem parenchyma cells?

A

Provide support

94
Q

What are the 2 things Translocation uses by mass flow?

A

Source
&
Sink

95
Q

Definition of source?

A

Part of plant that loads sugar into phloem

96
Q

Examples of source

A
  • Organs such as leaves/roots
  • Tissues such as palisade mesophyll/root cortex
97
Q

Definition of sink?

A

Part of plant that unloads sugar from phloem

98
Q

Examples of sink

A
  • Root and shoot tips - cell wall formation, cell div. & respiration
  • Fruits and meristem tissue
99
Q

How does the plant ensure there is always a conc. gradient from source to sink?

A
  • Enzymes in sink covert assimilates
  • Into something else
  • Ensuring there’s always a
  • Lower conc. at the sink

e.g. sucrose -> starch when reaches sink

100
Q

Look in book for evidence of translocation occurring in phloem
(cuz im only gonna add that ringing experiment)

A

<_<

101
Q

What is the ringing experiment?

A
  • Ring of phloem around stem removed
  • Xylem left intact

(trees n shit)

102
Q

Why is there a bulge above ring in the ringing experiment?

A
  • Sucrose still being produced in source
  • Travels down phloem
  • Cannot go past ring
103
Q

Why is there no growth below ring in ringing experiment?

A
  • Not receiving any more sucrose
  • After all sucrose stores being used up
  • No sucrose available for respiration
104
Q

Look in book for diagram and labelling of mass flow hypothesis

A

:(

105
Q

Evidence 1 for pressure flow theory (mass flow)

A
  • Ringing experiment:
  • Analysis of ‘bulge’
  • Shows high sugar conc.
  • Sugars can’t move past area
  • Gives evidence of downward flow of sugars
106
Q

Objection 1 against pressure flow theory (mass flow)

A
  • Not all solutes in phloem sap move at same rate
  • e.g. sucrose & amino acids
  • Move at different rates
  • And in different directions
  • in same tissue
  • (phloem has numerous sieve tubes, accounts for this)
107
Q

Evidence 2 for pressure flow theory (mass flow)

A
  • Aphids:
  • Sugar comes out of severed mouthpart
  • Faster nearer the leaves
  • than further down the stem
  • Evidence: no pressure gradient
108
Q

Objection 2 against pressure flow theory (mass flow)

A
  • Rate of phloem transport =
  • 10 000 times faster
  • Than if substances were moving by
  • Diffusion
109
Q

Evidence 3 for pressure flow theory (mass flow)

A
  • Sucrose conc. higher
  • in source than in sink
110
Q

Objection 3 against pressure flow theory (mass flow)

A
  • Doesn’t take into account the sieve plates:
  • Sieve plates would create barrier to mass flow
  • A lotta pressure needed
  • For assimilates to get through
  • At a reasonable rate
111
Q

Explain cytoplasmic streaming?
(step 1)

A
  1. Cytoplasm of each sieve tube element
    - Circulates around cell
112
Q

Explain cytoplasmic streaming?
(step 2)

A
  1. Solutes may then be actively transported across sieve plate
    - either up/down
113
Q

Explain cytoplasmic streaming?
(step 3)

A
  1. If correct this accounts for movement
    - In both directions
    - & use of ATP
114
Q

Sucrose loaded into companion cells by active process
(step 1)

A
  1. ATP used by companion cells
    - To actively transport sucrose
    - Into companion cells
115
Q

Sucrose loaded into companion cells by active process
(step 2)

A
  1. As sucrose conc. builds up
    - In companion cells,
    - They diffuse into sieve tube elements
    - Through plasmodesmata
116
Q

Sucrose loaded into companion cells by active process
(step 3)

A
  1. Water potential inside sieve tube,
    - Reduced
    - Due to presence of sucrose
117
Q

Sucrose loaded into companion cells by active process
(step 4)

A
  1. Water molecules move into sieve tube
    - By osmosis
    - From surrounding tissues
    - e.g. Xylem
118
Q

Sucrose loaded into companion cells by active process
(step 4.5)

A

4.5. Increases hydrostatic pressure
- In sieve tube at the source
- Mass flow occurs
- Sap moves through the phloem

119
Q

Sucrose loaded into companion cells by active process
(Step 5)

A
  1. AT THE SINK:
    - Sucrose moves from sieve tubes
    - To surrounding sink tissues
    - By diffusion/active transport
    - And either used in respiration
    - Or converted and stored as another substance
    - (starch)
120
Q

Sucrose loaded into companion cells by active process
(Step 5.5)

A

5.5. Has effect of increasing psi
- In sieve tube at sink
- So water leaves sieve tube
- And enters surrounding tissues e.g. xylem
- Reduces hydrostatic pressure in phloem
- at sink and maintains
- Pressure gradient from source to sink

121
Q

And yet after all of this writing, what is quite literally the most next important damn thing?

A

Answer questions :(

Why is there 121 fucking flashcards

Bio A Levels Unit 2 Linton/Jones re-run (5 decks)

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