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A Level Biology > Transport In Plants > Flashcards

Transport In Plants Flashcards

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1
Q

Why do plants need a transport system

A

All living things need to take substances from and return wastes to their environment
- larger plants have a smaller surface area to volume ratio

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2
Q

What do plants use transport systems for

A
  • move water and minerals from the roots up to the leaves
  • move sugars from the leaves to the rest of the plant
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3
Q

What are the vascular tissues

A
  • xylem
  • phloem
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4
Q

What does the xylem do

A

Transport water and mineral ions up the plants

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5
Q

What does the phloem do

A

Transports assimilates (sugars) up or down the plant

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6
Q

What are dicotyledonous plants

A

Plants that have two seed leaves

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7
Q

Where is the vascular bundle found in young roots

A

The center core
- shape of an X

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8
Q

Where are the phloem in young roots

A

In between the x shape

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9
Q

Where is the vascular bundle in stems

A

Near the outer edge of the step

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10
Q

Where is the xylem in the vascular bundle of stems

A

On the inside

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11
Q

What is in between the phloem and xylem in stems

A

Cambium

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12
Q

What is the cambium

A

A layer of meristem cells that divide to produce new xylem and phloem

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13
Q

What do xylem tissue consist of

A
  • vessels to carry the water and dissolved mineral ions
  • fibres to help support the plant
  • living parenchyma cells which act as packing tissue to separate and support the vessels
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14
Q

What does lignin do

A

Impregnates the walls of the xylem cells
- makes the walls waterproof

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15
Q

What are the cells in xylem like

A
  • lignin kills the cells
  • end walls and contents of cells decay
  • long column of dead cells with no contents
  • xylem vessels
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16
Q

What are pits

A

Allow water to leave one vessel and across into the next vessel
- latterly

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17
Q

What are the adaptations of xylem

A
  • made from dead cells aligned end to end to form continuous columns
  • tubes are narrow, water column does not break easily and capillary action can be effective
  • pits in the walls allow water to move sideways from one vessel to another
  • lignin develops in spirals to allow them to bend and stretch
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18
Q

How is the flow of water not impeded in xylem

A
  • there are no cross-walls
  • there are no cell contents, nucleus or cytoplasm
  • lignin thickening prevents the walls from collapsing
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19
Q

What does sucrose dissolved in water make in plants

A

Sap

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20
Q

What are sieve tubes made of

A
  • sieve tube elements
  • companion cells
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21
Q

What are sieve tube elements

A
  • elongated sieve tube elements are lined up ene to end to form sieve tubes
  • contain no nucleus and very little cytoplasm
  • leaves space for mass flow of sap to occur
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22
Q

What are sieve plates

A
  • perforated cross-walls
  • allows movement of sap from one element to the next
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23
Q

What are companion cells

A
  • small cells
  • large nucleus
  • dense cytoplasm
  • numerous mitochondria (ATP needed for active processes)
  • carry out metabolic processes
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24
Q

What is plasmodesmata

A

Small gaps between cells
- cytoplasm flows between cells

25
Q

What is the apoplast pathway

A

Water passes through the spaces in the cell walls and between cells
- doesn’t pass through cytoplasm
- water moves by mass flow
- stoped by casparian strip

26
Q

What is the symplast pathway

A

Water enters the cytoplasm through the plasma membrane
- passes through the plasmodesmata

27
Q

What is water potential

A

The tendency of water molecules to move from one place to another

28
Q

What happens to water potential if high concentration

A

Low water potential

29
Q

What direction does water move along water potential

A

From high to low
- down gradient

30
Q

What is transpiration

A

The evaporation and diffusion of water out of the stomata

31
Q

What is the pathway of water leaving through the leaf

A
  • water enters the leaf through the xylem
  • enters cells by osmosis or apoplast pathway
  • water evaporates from the cell walls of the spongy mesophyll
  • water vapour moves by diffusion out of the cell
32
Q

Similarities between phloem and xylem

A
  • cells joined end to end
  • made of multiple cell types
  • complex tissues
33
Q

Differences between phloem and xylem

A
  • x lignified, p not
  • x continuous and hollow, p sieve plates
  • x no companion cells, p do
  • x have pits, p do not
34
Q

What does the movement of transpiration do

A
  • transports useful mineral ions up the plant
  • maintains cell turgidity
  • supplies water for growth, cell elongation and photosynthesis
  • supplies water that, as it evaporates, can keep the plant cool of a hot day
35
Q

How does light intensity effect transpiration rates

A

In light
- stomata open to allow gaseous exchange
- higher light intensity increases transpiration rates

36
Q

How does temperature effect transpiration rates

A

Higher temperature
- increase rate of transpiration
- increase rate of evaporation
- increased rate of diffusion
- decrease the relative water vapour potential in the air

37
Q

How does humidity effect transpiration rates

A
  • higher relative humidity will decreases the rate of water loss
  • smaller water vapour potential gradient
38
Q

How does air movement affect rate of transpiration

A
  • air movement out of the leaf will carry away water vapour
  • maintains a high water vapour potential gradient
39
Q

How does water availability affect transpiration rates

A
  • little water in soil, plant cannot replace the water it lost
  • if too little water stomata close and plant wilts
40
Q

How does water flow up the plant

A

Through the xylem by mass flow

41
Q

What is root pressure

A

Small pressure pushing water a short way up the xylem

42
Q

What is adhesion in the stems

A

Water attaches to other water molecules and surfaces due to hydrogen boning

43
Q

What is cohesion in the stem

A

Water attaches to other water molecules due to hydrogen bonding

44
Q

What is transpiration pull

A

The loss of water by evaporation from the leaves must be replaced by water coming up the xylem
- forces of cohesion

45
Q

What must plants on land be adapted to

A
  • reduce loss of water
  • replace water that has been lost
46
Q

Structural and behavioural adaptation that terrestrial plants have done to prevent water loss

A
  • waxy cuticle reduces evaporation of water
  • stomata are found on the bottom of the leaves
  • stomata are closed at night
  • lose their leaves during the winter
47
Q

What is a xerophyte

A

Plants that have adapted to live in very dry conditions

48
Q

How have xerophytes adapted to their conditions

A
  • leaf is rolled so that air is trapped inside
  • thick waxy cuticle
  • stomata on the inner side of the rolled leaf
  • stomata are in pits
  • spongy mesophyll is very dense
  • store water in their stems
  • stem is green for photosynthesis
  • roots are wide set
  • closing stomata when needed
  • low water potential inside their leaf
  • long tap root
49
Q

Examples of xerophytes

A
  • marram grass
  • cacti
50
Q

What is translocation

A

Mass flow of sucrose in the phloem from the source to the sink

51
Q

What is a source in transpiration

A

Part of the plant that loads assimilates into the phloem sieve tubes

52
Q

What is a sink in transpiration

A

A part of the plant that removes assimilates from the phloem sieve tubes

53
Q

What type of process loads sucrose into the sieve tube

A

Active loading/process
- involves the use of energy from ATP in the companion cells

54
Q

What is the energy in active loading used for

A

Actively transport hydrogen ions out of the companion cells

55
Q

What is Co transport

A

Coupled movement of substances across a cell membrane via a carrier protein
- combination of facilitated diffusion and active transport

56
Q

What is caused by sucrose moving into the phloem

A

Hydrostatic pressure

57
Q

What does hydrostatic pressure cause

A

Pressure gradient

58
Q

What happens at the source of transpiration

A
  • sucrose enters the phloem
  • lowers the water potential gradient
  • water enters the phloem
  • causes sap to move down the phloem
59
Q

What happens at the sink in transpiration

A
  • sucrose leave the phloem
  • increases the water potential
  • water leaves the phloem

A Level Biology (13 decks)

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