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module 3: exchange and transport > 3.3 transport in plants > Flashcards

3.3 transport in plants Flashcards

1
Q

Why do plants need a transport system

A

Large plants have a small SA:V - need specialised exchange surfaces/ transport system

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2
Q

What do plants need a regular supply of

A

Water
Nutrients
Minerals
Oxygen

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3
Q

Why can plants not use diffusion alone

A

High metabolic demand
Large size
Small SA:V
Diffusion is too slow

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4
Q

What is the vascular bundle made of

A

Xylem
Phloem

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5
Q

What does xylem transport

A

Water and mineral ions

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6
Q

What does phloem transport

A

Sucrose and amino acids

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7
Q

What does herbaceous dicotyledonous plants mean

A

Non woody stem , 2 seed leaves plant

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8
Q

How do you dissect a plant

A

Stain
Cut stem longitudinaly or transversely

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9
Q

Describe the structure of xylem tissue

A

Xylem vessels which carry water
Hollow tubes
Elongated
End region of cell lost
Non lignified pit
Thick, lignified wall

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10
Q

What is the purpose of pits in xylem

A

Lateral water movement

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11
Q

What is the purpose of lignin in xylem

A

Waterproof and lignin spirals reinforces vessels so it doesn’t collapse

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12
Q

How does a continuous column form in xylem

A

Dead cells aligned end to end , end regions have been lost

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13
Q

Why are narrow tubes in xylem beneficial

A

Prevents breaking easily, capillary action effective

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14
Q

What are assimilates

A

Sucrose and amino acids

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15
Q

What do phloem consists of

A

Sieve tube elements
Companion cells

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16
Q

What are sieve tube elements

A

Elongated tubes lined up end em to end with sieve plates at the end (of the sieve tube elements)

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17
Q

What do sieve tubes contain and why is it beneficial

A

No nucleus and very little cytoplasm - allows mass flow of sap

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18
Q

What do sieve plates allow

A

Movement of sap from elements

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19
Q

How are companion cells specialised

A

Large nucleus
Dense cytoplasm
Lots of mitochondria

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20
Q

How are companion cells and sieve tube elements joined

A

Plasmodesmata - gaps in cell wall that connects cell

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21
Q

What do companion cells do

A

carry out active processes to actively load assimilates into sieve tubes

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22
Q

How is the vascular bundle structured in the roots

A

Central core of xylem in X shape
Phloem in the arms of xylem
Endodermis around the vascular bundle
Layer of meristem in the epidermis

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23
Q

How is the vascular bundle arranged in the stem

A

Found on the outer edge - Phloem on the outside and xylem on the middle side
Cambium found in the middle
Cortex

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24
Q

How is the vascular bundle arranged in the leaf

A

Xylem ontop of the phloem in the veins of the leaf
Vascular bundle called a midrib

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25
What is transpiration
Loss of water vapour from upper parts of the plant via evaporation and diffusion
26
What is the transpiration steam
Flow of water from the root to the leaves in plants where it’s lost by evaporation
27
What happens during transpiration
Water enters the leaf through xylem Moves by osmosis into cells in spongy mesophyll Water evaporates from cell walls of spongy mesophyll Water vapour moves out of leaf through open stomata down the water potential gradient
28
How is water pulled up a stem
Transpiration pull/ stream (cohesion) Root pressure (active process) Capillary action (adhesion)
29
What is the importance of transpiration
Transports mineral ions up the plant Maintains cell turgidity Water for growth , cell elongation and photosynthesis Keeps plant cool
30
How much water is lost by transpiration
95%
31
What environmental factors affect transpiration
Light intensity Temperature Humidity Wind/ air movement Water
32
How does light intensity impact transpiration
Bright LI = stomata open for photosynthesis = increases ROT
33
How does temperature impact respiration
Higher temp = more evaporation = more kinetic energy = water potential will increase so increased ROT
34
How does humidity impact respiration
Higher humidity = lowers rate of water loss - smaller water vapour potential gradient between air spaces in leaf and outside
35
How does wind/ air movement impact respiration
Moving air = water vapour carried away = maintains a water potential gradient
36
How does water impact transpiration
Little water in soil = plant cannot replace water lost = stomata close
37
How is water lost through leaves
lost as water vapour through open stomata Which lowers water vapour pressure in gaps = more water moves down gradient
38
What is translocation
Movement of assimilates throughout the plant in the phloem
39
What are assimilates
Substances that have become apart if the plant (sucrose, amino acids)
40
What is the source
Part of the plant that loads assimilates into phloem sieve tubes
41
What is the sink
Part of the plant that removes assimilates from phloem sieve tubes
42
What are the order of processes in active loading
1. Active transport 2. facilitated diffusion 3. Simple diffusion 4. Osmosis
43
Explain how active loading works
Active transport of H+ ions out of the companion cells using ATP from mitochondria in companion cells - creates concentration gradient H+ ions diffuse back into via facilitated diffusion through cotransport proteins and brings sucrose with it Higher conc. of sucrose in companion cells then in the sieve tubes so sucrose moves by simple diffusion Water potential in sieve tubes decrease so water moves in tubes by osmosis
44
What is plasmodesmata
Gaps in cell wall which connects two cells
45
What are the systems that water through plants
Apoplast Symplast Vacuolar
46
Explain the apoplast system
Water passes through spaces in the cell wall / between the cells Doesn’t pass through plasma membranes into cells Moves by mass flow
47
Explain the symplast system
Water enters cell through the plasma membrane and passes through the plasmodesmata from cells to the next
48
Explain the vacuolar pathway
Passes through vacuole as well as symplast
49
What is the casparian strip
Waxy, waterproof strip impervious to water and stops water entering by apoplast and forces it through the plasma membrane (symplast)
50
What is the casparian strip made of
Suberin
51
What is water potential
Measure of tendancy of water molecules to move from one place to another
52
How does water move in a concentration gradient
Down the concentration gradient Moves from higher water potential to lower water potential
53
How does water move in cells in plants
Water leaves the cell down the water potential gradient As higher conc of mineral ions and sugars outside the cell so there is a lower water potential (more negative) Water moves from cell to more negative cell
54
How is water taken up by a plant
W.P is more negative in the cell so water moves in by osmosis
55
What does turgid meant
Cell full of water and exerts pressure on cell wall making it stiff
56
What is pressure potential
Water exerting pressure on walls
57
How is water lost from a plant
Transpiration (evaporation)
58
What happens when a plant is placed in salt solution
Has very negative water potential so water moves out
59
What happens if water loss continues in a plant
Cytoplasm and vacuole shrink No longer turgid -> plasmolysis (plasma membrane shrinks) cell is now flaccid
60
What does plasmolysis mean
Plasma membrane shrinks
61
What are terrestrial plants
Plants living on land
62
How do terrestrial plants exchange gases
Through stomata
63
Why do stomata need to be open
Allow CO2 moves in Water loss Allow 02 to be removed as a product
64
explain adaptations of terrestrial plants
Waxy cuticle - reduce water loss by evaporation Stomata on under surface of leaves - reduces evaporation from direct sun Closed stomata at night - no light for photosynthesis Deciduous plants lose leaves in the summer
65
What is a hydrophyte
Plant that’s adapted to living in water/ very wet ground
66
What is an example of a hydrophyte
Water lily
67
Adaptations of water lilies
Stomata on upper epidermis - exposed to gases Large air spaces - buoyancy in stem, O2 diffuse quickly Thin waxy cuticle - don’t need to conserve water Wide, flat leaves - increases SA , lots of sunlight available
68
What is the difficulty with water lilies
Struggle with oxygen getting to submerged tissues
69
What is a xerophyte
Plant adapted to living in dry conditions/ arid conditions
70
What are examples of xerophytes
Cactus Marram grass
71
Adaptions of cactus
Succulents - store water in stem, become fleshy and swollen Stem is ribbed/ fluted - expand when water available Spines - reduce SA and water loss Widespread roots - water underground Thick, waxy cuticle - reduce evaporation Sunken stomata/ pits - create local humidity, reduces air exposure
72
Adaptations of marram grass
Thick, waxy cuticle - reduce evaporation Stomata in pits, covered in hair reduce air movement, trap water Dense spongy mesophyll - reduce water evaporation Stomata on inner side of leaf - protected Outer epidermis

module 3: exchange and transport (3 decks)

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