Unit 2.3 Plant Transport Flashcards
1
Q
What process used to take mineral ions from soil in plants?
A
Active transport
2
Q
How can active transport occur?
A
Need ATP
3
Q
How can the plant produce ATP?
A
Respiration in mitochondria
4
Q
What process used to move water in plants?
A
Osmosis
5
Q
Quickly define osmosis?
A
- Movement of water molecules
- Down a water pot. gradient
- Through a selectively permeable membrane
6
Q
How to decrease water potential?
A
Increase conc. of solutes (mineral ions in cytoplasm)
7
Q
How plant can photosynthesise?
A
Stomata pores open,
allowing gas exchange
8
Q
Quick equation of photosynthesis?
A
CO2 + H2O -> Glucose + O2
-> = light energy
9
Q
What consists of the vascular system?
A
Xylem + Phloem
10
Q
Why would plants have a vascular system?
A
Idk?? Height of plants can pose problems (constant supply)
bro idk….
11
Q
Without vascular tissues in plants = ?
A
- Diffusion would be too slow
- Diffusion pathway would be too long
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]
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]
14
Q
Define mass flow?
A
- Bulk movement of substances
- From one area to another area
- Along pressure gradients
- Due to pressure differences
15
Q
Look in book for T.S. root diagram
A
:<
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)
17
Q
Look in book for T.S. stem diagram
A
,:<
18
Q
Look in book for T.S. leaf diagram
A
,’:<
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
20
Q
Step 2 of water transport in plants?
A
- Water moves into root hairs
- Down the water pot. gradient
- By osmosis
21
Q
Step 3 of water transport in plants?
A
- Water enters xylem of root
22
Q
Step 4 of water transport in plants?
A
- Water moves up xylem of stem
23
Q
Step 5 of water transport in plants?
A
- Water moves from leaf xylem
- To mesophyll cells
- In leaf
24
Q
Step 6 of water transport in plants?
A
- Evaporation of water into air spaces
25
Step 7 of water transport in plants?
- Diffusion of water vapour
- Through stomata
- Into air
26
Oh and make sure u look in book for diagram of water transport in plants
':|
27
What is the transpiration stream?
Movement of water across the root ig?
28
After water absorbed into root hair cell, why water continue journey across root cortex?
- Water pot. in xylem lower than water pot. in
- Root hairs and cells in between
29
3 ways of transpiration stream?
1. Apoplast pathway
2. Symplast pathway
3. Vacuolar pathway
30
Make sure u look in book for diagram of them pathways
¬.¬
31
Brief info of apoplast pathway?
- Mass flow through plant cell walls
32
Brief info of symplast pathway?
- Osmosis through cytoplasm & plasmodesmata
33
Brief info of vacuolar pathway?
- Similar to symplast, swap cytoplasm with vacuoles
34
Which transpiration stream pathway faster and why?
- Apoplast pathway
- Less resistance
35
Look in book for that casparian strip thingy
¬>¬
36
Define protoplast?
Living part of a cell e.g. nucleus
37
Why substances move across endodermis into the xylem by symplast route only?
(7 steps D:)
- 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
38
Endodermal cells move minerals by active transport from the cortex into the xylem
How does this affect the water pot. in xylem?
- Lowers water pot. in xylem
- So water moved from cortex to xylem by osmosis
39
Step 1 of water transport through leaves?
- Water enters xylem vessels
- Of the leaf from the stem xylem
40
Step 2 of water transport through leaves?
- Water leaves xylem
- Enters mesophyll cells by osmosis
41
Step 3 of water transport through leaves?
- Water evaporates from cell walls
- Of mesophyll cells
- Collects in the air spaces as
- Water vapour
42
Step 4 of water transport through leaves?
- As water vapour collects here
- Water vapour pot. in air spaces
- Increases
43
Step 5 of water transport through leaves?
- When water vapour pot. in
- air spaces = higher than outside
- Water vapour diffuses
- out of leaf via
- Open stomata
44
Step 6 of water transport through leaves?
- Air movements carry water vapour
- Away from leaf surface
- Maintains water vapour pot. gradient
45
The main force that pulls water up the xylem is evaporation of water from leaves - a process called....?
Transpiration
46
What allows the column of water to be **pulled up** to the stem?
- Tension to the column of water
- During transpiration
47
What are the 3 theories regarding of the movement of water up the stem in the xylem?
1. Root pressure theory
2. Capillarity/**Adhesion** theory
3. Cohesion-tension theory
48
Explain root pressure theory
(6 things)
- 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
49
Explain capillarity/**adhesion** theory
(6 things)
- 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
What is cohesion-tension theory?
It's the main mechanism of movement of water + involves transpiration of water from leaf
51
Step 1 of cohesion-tension theory?
1. Water evaporates from spongy mesophyll cells
- Into air spaces & diffuses out of stomata
- Down water pot. gradient
52
Step 2 of cohesion-tension theory?
2. Creates water pot. across leaf
- From higher water pot. in xylem
- To lower water pot. in air spaces
53
Step 3 of cohesion-tension theory?
3. 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
Step 4 of cohesion-tension theory?
4. 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
Step 5 of cohesion-tension theory?
5. Water molecules also attracted to hydrophilic lining
- Of xylem vessels
- This is adhesion
- Contributes to water movement
- Up the xylem
56
How diameter of a tree trunk smaller in middle of the day than in morning & evening?
(3 things)
- Increased transpiration during noon
- Produces negative pressure
- Reduces diameter
57
Why should ya cut stems of flowers... and place them in a vase all under water?
- Stop air bubbles getting into xylem
- And breaking water column
58
Look in book for structure of xylem
O_o
59
Look in book for T.S. & L.S. of xylem vessel
o-o'
60
Why do lignin form patterns in the cell wall?
(3 things)
- Spiral patterns allows flexibility
- Whilst still preventing
- Collapse or breakage
61
No cell contents
(How xylem's structure is related to its function)
- Hollow lumen
- Less resistance to water flow
62
Lignin in cell walls
(How xylem's structure is related to its function)
- Supports walls
- Prevents collapse due to tension in xylem
- Hydrophilic lining allows adhesion
63
Pits in cell walls
(How xylem's structure is related to its function)
- Allows lateral movement of water
- Out of xylem to other xylem
-, Phloem or surrounding cells
64
Narrow tubes
(How xylem's structure is related to its function)
- Capillary action more effective
- Water column doesn't break easily
65
Elongated cells, no end walls
(How xylem's structure is related to its function)
- Continuous column of water
- For free flow
- Less resistance
66
Wide lumen
(How xylem's structure is related to its function)
- Ease of flow of water
67
Uhhhhh, we may have an issue for the transpiration part of the booklet
;-;
68
Why is transpiration unavoidable?
- Allow CO2 into leaves for photosynthesis
69
Features of mesophytes?
(4 things)
- 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
What are xerophytes?
('xero' = dry 'phyte' = plant)
Plants well adapted to live in very dry/arid conditions
71
Look in book for diagrams of a buncha xerophytes
O_O_O_O
72
Stomata are sunken in pits
(How xerophytes adapted to reduce water loss by transpiration)
- 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
Hairs/trichomes
(How xerophytes adapted to reduce water loss by transpiration)
- Trap water vapour
- Reduce water pot. gradient
74
Rolled leaves
(How xerophytes adapted to reduce water loss by transpiration)
- Reduces surface area exposed to environment
- e.g. stomata 'inside'
- Reduces air movements past lower epidermis
- Same as hairs/trichomes
75
Few stomata
(How xerophytes adapted to reduce water loss by transpiration)
- Reduces water loss
- Cuz less pores
- Less water escaping
76
Thick waxy cuticle
(How xerophytes adapted to reduce water loss by transpiration)
- Waterproof
- Reduces evaporation of water
- From epidermis
77
Smaller/fewer leaves or needle-like leaves
(How xerophytes adapted to reduce water loss by transpiration)
- Fewer stomata
- Less surface area
78
Stoma shut in day
(How xerophytes adapted to reduce water loss by transpiration)
- Little/no water vapour loss
- From stomata of leaves
- During day
79
Long roots/spread out roots
(How xerophytes adapted to reduce water loss by transpiration)
1. To get water deep underground
2. To catch rainfall
80
Low water pot. inside cells (by maintaining high salt conc. in cells)
(How xerophytes adapted to reduce water loss by transpiration)
- Reduces evaporation
- And diffusion of water
- Cuz gradient reduced
81
Stiff sclerenchyma fibres in leaf
(How xerophytes adapted to reduce water loss by transpiration)
- Maintains shape of leaves
- If cells get plasmolysed/flaccid
82
What are hydrophytes?
Plants that grow partially/wholly submerged in water
e.g. water lily
83
Look in book for diagrams of hydrophytes
0_0
84
No lignified support tissues
(Adaptations of hydrophytes features)
- Water provides support
- So no need
85
Xylem poorly developed
(Adaptations of hydrophytes features)
- Surrounded by water
- Don't need transport tissues
86
Leaves have little cuticle
(Adaptations of hydrophytes features)
- No need to prevent water loss
87
Stomata on upper surface
(Adaptations of hydrophytes features)
- Upper surface exposed to air
88
Stems and leaves have large air spaces
(Adaptations of hydrophytes features)
- Provide buoyancy (float on water)
89
Look in book for L.S. & T.S. Phloem diagrams
T-T
90
Explain sieve tubes' lack of cell contents
(no nucleus/gorgi/tonoplast/ribosomes)
No obstruction to flow
91
Why companion cells of many mitochondria?
(3 things)
- Producing high level of ATP
- Active transport involved in
- Movement of substances
92
Look in book for the labelling of phloem
T_T_T
93
Function of phloem parenchyma cells?
Provide support
94
What are the 2 things Translocation uses by mass flow?
Source
&
Sink
95
Definition of source?
Part of plant that **loads** sugar into phloem
96
Examples of source
- Organs such as leaves/roots
- Tissues such as palisade mesophyll/root cortex
97
Definition of sink?
Part of plant that **unloads** sugar from phloem
98
Examples of sink
- Root and shoot tips - cell wall formation, cell div. & respiration
- Fruits and meristem tissue
99
How does the plant ensure there is always a conc. gradient from source to sink?
- 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
Look in book for evidence of translocation occurring in phloem
(cuz im only gonna add that ringing experiment)
<_<
101
What is the ringing experiment?
- Ring of phloem around stem removed
- Xylem left intact
(trees n shit)
102
Why is there a bulge above ring in the ringing experiment?
- Sucrose still being produced in source
- Travels down phloem
- Cannot go past ring
103
Why is there no growth below ring in ringing experiment?
- Not receiving any more sucrose
- After all sucrose stores being used up
- No sucrose available for respiration
104
Look in book for diagram and labelling of mass flow hypothesis
:(
105
Evidence 1 **for** pressure flow theory (mass flow)
- Ringing experiment:
- Analysis of 'bulge'
- Shows high sugar conc.
- Sugars can't move past area
- Gives evidence of downward flow of sugars
106
Objection 1 **against** pressure flow theory (mass flow)
- 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
Evidence 2 **for** pressure flow theory (mass flow)
- Aphids:
- Sugar comes out of severed mouthpart
- Faster nearer the leaves
- than further down the stem
- Evidence: no pressure gradient
108
Objection 2 **against** pressure flow theory (mass flow)
- Rate of phloem transport =
- 10 000 times faster
- Than if substances were moving by
- Diffusion
109
Evidence 3 **for** pressure flow theory (mass flow)
- Sucrose conc. higher
- in source than in sink
110
Objection 3 **against** pressure flow theory (mass flow)
- 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
Explain cytoplasmic streaming?
(step 1)
1. Cytoplasm of each sieve tube element
- Circulates around cell
112
Explain cytoplasmic streaming?
(step 2)
2. Solutes may then be actively transported across sieve plate
- either up/down
113
Explain cytoplasmic streaming?
(step 3)
3. If correct this accounts for movement
- In both directions
- & use of ATP
114
Sucrose loaded into companion cells by active process
(step 1)
1. ATP used by companion cells
- To actively transport sucrose
- Into companion cells
115
Sucrose loaded into companion cells by active process
(step 2)
2. As sucrose conc. builds up
- In companion cells,
- They diffuse into sieve tube elements
- Through plasmodesmata
116
Sucrose loaded into companion cells by active process
(step 3)
3. Water potential inside sieve tube,
- Reduced
- Due to presence of sucrose
117
Sucrose loaded into companion cells by active process
(step 4)
4. Water molecules move into sieve tube
- By osmosis
- From surrounding tissues
- e.g. Xylem
118
Sucrose loaded into companion cells by active process
(step 4.5)
4.5. Increases hydrostatic pressure
- In sieve tube at the source
- Mass flow occurs
- Sap moves through the phloem
119
Sucrose loaded into companion cells by active process
(Step 5)
5. **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
Sucrose loaded into companion cells by active process
(Step 5.5)
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
And yet after all of this writing, what is quite literally the most next important damn thing?
Answer questions :(
Why is there 121 fucking flashcards
