Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Worcester Sixth Biology 101 > Transport in Plants > Flashcards

Transport in Plants Flashcards

(62 cards)

Start Studying
1
Q

What is the xylem?

A

vascular tissue that transports water and mineral salts, from roots to leaves in the transpiration stream

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

what is the phloem?

A

vascular tissue, transports organic solutes from sources to sinks by translocation

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

what is transpiration?

A

the evaporation of water from aerial parts of the plant, i.e leaves, petals, and lenticels

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

what is translocation?

A

the bidirectional movement of organic solutes like sucrose and amino acids in the phloem

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

what is a source?

A

where carbohydrate is made via photosynthesis. Leaves

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

what is a sink?

A

where carbohydrate is stored or used for growth. Roots

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

What are angiosperms?

A

flowering plants

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

What cell types does xylem consist of?

A

vessels (angiosperms)
tracheids (ferns, conifers, angiosperms)
Fibres
Parenchyma

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

What cell types do Phloem consist of?

A

Sieve tube elements
Companion cells
Fibres
Parenchyma
Transfer Cells

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

What is the structure of xylem vessels?

A

they are straight tubes, so water moves up fast

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

what is the structure of tracheids?

A

they are spindle shaped so water takes a slower twisting route up

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

What is lignification?

A

Vessels and tracheids have their cellulose cell walls layered with lignin, it laid down in different patterns

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

What are the properties of lignin?

A

It is rigid and waterproof

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

What is the purpose of lignification?

A

to thicken cell walls
to strengthen cell walls

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

How does thickening of cell walls in lignification help the plant?

A

it gives the plant extra support

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

How does strengthening of cell walls during lignification help the plant?

A

prevents their collapse
through cohesion tension theory

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

What is the cohesion tension theory?

A

Transpiration pulls produce water tension in the xylem which pull the water upward and the cohesive and adhesive forces maintain the water column in the xylem.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does water enter/leave vessels and tracheids?

A

Gaps in the lignin thickening
Bordered pits (reinforced pores)

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

What is callose?

A

plant polysaccharide acts as a temporary cell wall and is laid down in areas of stress or damage

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

what are sieve tube elements?

A

no nucleus
end cell walls break to form sieve plates to allow cell-to-cell transport of organic solutes

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

what are companion cells?

A

have chloroplasts, large nucleus, mitochondria) retain cytoplasmic connections with sieve tube elements via plasmodesmata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are sites of water loss in plants?

A

Leaves (most via stomata and some across cuticle
Flowers
Stems or Lenticels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are environmental factors that can affect transpiration rate?

A

Humidity
Wind
Temperature
Sunlight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are internal factors that can affect transpiration rate?

A

Stomatal density
Thickness of waxy cuticle
Leaf surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How does water move through a plant (4 stages)?
1. Uptake by roots 2. Across cortex and into xylem 3. From roots to leaves in xylem 4. Loss from leaves
26
How is water taken up by roots?
by Osmosis via apoplastic pathway via root hairs which increase surface area
27
What is the apoplastic pathway?
non-living route across cortex along cellulose cell walls, between cells, and through intercellular air spaces
28
What is the symplastic pathway?
living route across the cortex cell to cell through cytoplasm, and across cell walls via plasmodesmata
29
what is the vacuolar pathway?
route across the cortex vacuole to vacuole by osmosis
30
What is the plasmodesmata?
cytoplasmic connections between plant cells
31
What is casparian strip?
composed of suberin, is waterproof, only allows water to cross the endodermis by symplastic pathway
32
What is the cohesion-tension theory?
cohesion means water molecules stick to each other and adhesion water molecules stick to the walls of the xylem vessels, the tension from evaporation of water from leaves pulls water upwards. Pull of transpiration
33
what is root pressure?
pull of transpiration aided by push from roots the endodermis actively pumps salts into the xylem this lowers the water potential in the xylem therefore water molecules 'follow' the salts into the xylem by osmosis down a water potential gradient
34
How is water lost from the leaves?
transpiration, water diffuses from intercellular spaces into the air via stomata down a water potential gradient
35
what are the adaptations of sieve tube elements?
no nucleus ,mitochondria, ribosomes or vacuole - so less resistance sieve plates - allows cell-to-cell movement
36
what are the adaptations of companion cells?
dense cytoplasm, many mitochondria for atp supply, plasmodesmata - to supply enzymes, proteins, and energy to sieve tubes
37
what are the adaptation of transfer cells?
modified companion cells that actively transfer organic solutes from sources into sieve tube elements many mitochondria for atp supply inner walls folded for increased surface area for uptake
38
what do organic solutes flow along?
a hydrostatic pressure gradient hypothesis
39
do sieve tubes in sources have a high or low hydrostatic pressure?
high
40
do sieve tubes in sinks have a high or low hydrostatic pressure?
low
41
what is the term for the flow of solutes from sources to sinks?
mass flow hypothesis
42
What does the mass flow hypothesis not account for in the phloem?
movement of sucrose in opposite directions in the same tube movement of sucrose at different rates
43
what other hypotheses have been proposed for movements of sucrose in the phloem?
Diffusion of sucrose and cytoplasmic streaming
44
What have radioactive tracer studies shown about phloem?
shows phloem translocates carbohydrates produced by photosynthesis, autoradiography studies using radioactive CO2 or radioactive sucrose shows that labelled carbohydrates entered the phloem for redistribution inside the plant, radioactive label first appears in the sieve tube elements of the phloem
45
Is sugar transport in the phloem regulated by gravity?
no, its bi-directional
46
How were aphids used in the theory of translocation?
aphids are small insects with stylets (needles like mouths) the positive pressure inside the sieve elements pumps the sap into the aphids who secrete drops of sucrose-rich 'honeydew' from their posterior. if aphids aphids are separated form their stylets the phloem sap will continue to flow from the stylet and can be collected and analysed. confirms sucrose is most commonly transported sugar and there is pressure in the phloem
47
What are mesophytes?
land plants growing in temperate regions that have an adequate water supply
48
What do mesophytes do during times of the year when water availability is decreased?
shed their leaves before winter (reduce transpiration water loss) aerial parts of non woody plants die so they are not exposed to frost or cold (underground organs e.g. bulbs survive) over-winter as dormant seeds with a low metabolic rate (require almost no water)
49
What are xerophytes?
plants that have adapted to survive in environments with very little water availability
50
What are some adaptations of maram grass (a type of xerophyte)?
Rolled leaves Sunken Stomata Stiff interlocking Hairs Thick waxy cuticle Stiff fibres of sclerenchyma
51
What do rolled leaves of maram grass (xerophyte) do?
reduces the leaf area exposed to air and so reduces transpiration
52
What do sunken stomata of maram grass (xerophyte) do?
As they are in pits/depressions humid air is trapped in the pit outside the stomata. this reduces the water potentail gradient between the inside of the leaf and the outside so reduces the rate of diffusion of water out through the stomata
53
What do the stiff interlocking hairs of maram grass (xerophyte) do?
trap water vapour and reduce the water potential gradient between the inside of the leaf and the rate of diffusion of water out
54
What does the thick waxy cuticle of maram grass (xerophyte) do?
wax is waterproof and so reduces water loss, the thicker the the cuticle the lower the rate of transpiration through the cuticle
55
What do the stiff fibres of sclerenchyma of maram grass (xerophyte) do?
stiff maintains the leaf shape even when cells become flaccid
56
What are hydrophytes?
plants that grow partially or fully submerged in water
57
How are hydrophytes adapted?
little or no lignified support tissues poorly developed xylem little or no cuticle on leaves stomata on upper surface of floating leaves large air spaces continuous down to roots
58
why do hydrophytes have little or no lignified support tissues?
water is a supportive medium
59
Why do hydrophytes have a poorly developed xylem?
they are surrounded by water so there is little need for water transport system
60
Why do hydrophytes leaves have little or no cuticle?
no need to prevent water loss, surrounded by water
61
Why are stomata on the upper surface of floating leaves of hydrophytes?
because the lower surface is in the water, therefore can't do gas exchange
62
Why do hydrophytes have large air spaces that are continuous down to roots?
forms a reservoir of oxygen and carbon dioxide which provide buoyancy

Worcester Sixth Biology 101 (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions