Brainscape's Knowledge GenomeTM

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


See full index

module 3 > 3.1.3 - transport in plants > Flashcards

3.1.3 - transport in plants Flashcards

1
Q

why do plants need transport systems?

A

metabolic demands - the underground parts of the plant need oxygen and glucose transported to them
size - some are very large
surface area to volume ratio - cannot rely on diffusion alone

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

cotyledons

A

organs that act as food stores for the developing embryo plant and form the first leaves when the seed germinates

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

dicotyledon

A

a plant that has two seed leaves or cotyledons

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

vascular bundle

A

plant stem structure that contains xylem and phloem tissue

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

xylem and phloem in the stem

A

xylem and phloem arranged into vascular bundles with cambium
xylem on inside, phloem on outside

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

xylem and phloem in the roots

A

vascular bundles are in the middle to help the plant withstand the tugging strains from wind
cross shaped xylem, and phloem around the xylem

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

xylem and phloem in the leaves

A

xylem on top, phloem on the bottom

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

structure of xylem

A

long continuous hollow tube
narrow lumen
wall made out of lignin (strong, waterproof and adhesive)
wall contains pits/pores, so water and minerals can leave

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

structure of the phloem

A

companion cells (lots of mitochondria for ATP for active loading)
sieve tube elements (little cell contents for ease of flow)
sieve plates (connect the elements together to allow for ease of flow)

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

purpose of water in plants

A

turgor pressure provides support
turgor drives cell expansion
loss of water means plants keep cool
mineral ions transported
raw material for photosynthesis

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

symplast pathway

A

water moves continuously through the cytoplasm of cells (connected through the plasmodesmata)

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

apoplast pathway

A

route through the cell walls and intercellular spaces or plants

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

Casparian strip

A

a water impermeable ring of wax in endodermal cells of plants that blocks the passive flow of water and solutes into the stele by way of cell walls

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

effect of Casparian strip

A

water can not carry on in the apoplast pathway so it is forced into the cytoplasm of the cell, joining the symplast pathway

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

significance of the Casparian strip

A

water now has to pass through the selectively permeable cell membranes, excluding any potentially toxic solutes in the soi; water from reaching living tissues

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

root pressure

A

the upward push of xylem sap in the vascular tissue of roots

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

evidence for the role of active transport in root pressure

A
  • if cyanide (affects mitochondria) is applied, root pressure disappears
  • increases with higher temps, decreases with lower temps
  • if oxygen falls, root pressure falls
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

transpiration

A

evaporation of water from the leaves of a plant, an inevitable consequence of gaseous exchange

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

transpiration stream

A

movement of water up through the xylem from the roots to the leaves

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

process of the transpiration stream

A

water molecules evaporate from the surface of mesophyll cells into air spaces in the leaf and move out of the stomata into surrounding air by diffusion
this lowers wp, so water moves in by osmosis
repeated across the leaf to the xylem, water moves out of xylem by osmosis into cells of the leaf
adhesion and cohesion cause capillary action and water is moved up.

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

capillary action

A

combind force of attraction among the water molecules and with the molecules of surrounding materials, causing water to rise up against the force of gravity.

22
Q

cohesion-tension theory

A

the mechanism of water movement from roots to the leaves due tovwater cohesion and water tension

23
Q

evidence for cohesion tension theory

A

changes in the diameter of trees - diameter grows at night when there is less transpiration
air is drawn into xylem when its broken

24
Q

how stomata control the rate of transpiration

A

when turgor is low, the guard cells close
when the environmental conditions are favourable, guard cells pump in solutes by active transport, increasing the turgor - guard cells become shaped and open pore

25
Q

how light affects transpiration

A

light is needed for photosynthesis, so stomata will be open in the day
more light, more stomata open, increasing the evaporation from the surfaces of leaves - more transpiration

26
Q

how humidity affects transpiration

A

if the air outside the leaf is humid, the concentration between water vapour inside and outside the leaf is less steep so there is less transpiration

27
Q

how temperature affects the rate of transpiration

A

increase in temperature increases the kinetic energy and there fore increases the rate of evaporation

28
Q

how air movement affects the rate of transpiration

A

blows away the layer of humid air surface, increasing gradient, meaning more diffusion (more transpiration)

29
Q

soil water availability and transpiration

A

if dry plant is under water stress so transpiration is reduced

30
Q

source (plant)

A

where assimilates like sucrose are loaded in to
e.g green leaves and stems, storage organs etc

31
Q

sink (plant)

A

where assimilates like sucrose are loaded out of
e.g roots that are growing and actively absorbing mineral ions, meristems taht are dividing.

32
Q

translocation

A

movement of carbohydrate through a phloem from a source to a sink

33
Q

assimilates

A

products of photosynthesis that are transported around a plant

34
Q

how assimilates are loaded into the phloem

A
  • H+ ions are pumped out of companion cells, using AT
  • this creates are diffusion gradient
  • therefore h+ ions are diffused back in, with a co transporter
  • sucrose is also transported in with this co transport protein
35
Q

structure of companion cells

A

many infoldings in their cell membranes to give an increased surface area for the active transport of sucrose in the cell cytoplasm
lots of mitochondria to supply ATP

36
Q

phloem unloading at sinks

A

diffusion of the sucrose from the phloem into surrounding cells, the sucrose rapidly moves on into other cells by diffision or is converted into another substance
loss of solutes from the phloem leads to a rise in the wp of the phloem, causing water to move out by osmosis

37
Q

evidence for translocation

A

advances in microscopyt allow us to see adaptations of CC
if mitochondria are poisoned, translocation stops
flow of sugar in phloem is 1000 times s=faster than diffusion alone, suggesting active process

38
Q

use of aphids with translocation

A

can demonstrate the translocation of organic solutes in the phloem. it has been shown that there is a positive pressure in the phloem that forced sap out the stylet

39
Q

xerophytes

A

plants with adaptations that allow them to survive in dry habitats

40
Q

examples of xerophytes

A

marram grass and cacti

41
Q

how waxy cuticle conserves water

A

minimises water loss due to the waterproof nature of the waxy cuticle

42
Q

sunken stomata

A

reduces water loss as the water has to travek a longer distance before it reaches the outside of the leaf

43
Q

reduced number of stomata

A

reduces transpiration rate and alos their gas exchange capabilities

44
Q

reduced leaves

A

reducing the total number of leaves and size of leaves will reduce the surface area available for water loss

45
Q

hairy leaves

A

create a microclimate of still humid air, reducing transpiration

46
Q

succulents

A

store water in a specialised parencyma tissue in their stems and toots which are used up in times of drought

47
Q

hydrophytes

A

plants taht have special adaptations to allow them to live in areas often saturated by water

48
Q

examples of hydrophytes

A

water lillies and water cross

49
Q

aerenchyma

A

a soft plant tissue containing air spaces found especially in many aquatic plants

50
Q

adaptations of hydrophytes

A

very thin or no waxy cuticle
lots of stomata that are always open
wide flat leaves
air sacs
small roots

module 3 (3 decks)

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