Brainscape's Knowledge GenomeTM

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


See full index

Year 1 biology > 3.1.3 transport in plants > Flashcards

3.1.3 transport in plants Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

what does autotrophic mean
3.1.3(a)

A

they produce their own food
eg-they use photosynthesis to make glucose

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

how do plants transport water and mineral ions
3.1.3(a)

A

they transport water and mineral ions from roots to all other parts of the plant for tugidity

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

how to plants transport assimilates
3.1.3(a)

A

they transport assimilates from sources to sinks

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

why don’t plants need to transport oxygen and carbon dioxide
3.1.3(a)

A

as they hvae a lower metabolic rate than animals (but still high)
so dont need to rapidly transport oxygen and carbon dioxide
it simply diffuses from the air to the inside of the leaf
-need transport systems to meet the high metabolic rate

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

why do plants need transport systems
3.1.3(a)

A

they have a small SA:V ratio
large diffusion distance
need to transport water and mineral ions from roots to all parts of the plant

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

what is the cambium
3.1.3(b)

A

thin layer between xylem and phloem
not always shown in diagrams

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

where does the xylem point in leaves
3.1.3(b)

A

in leaves, the xylem in each vascular bundle points to the upper surface of the leaf

TIP-L for layer + leaf so upper surface of the ;eave

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

where does the xylem point in stems
3.1.3(b)

A

in stems, the xylem in each vascular bundle points inward to the middle of the stem.

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

what does the xylem form in roots
3.1.3(b)

A

in roots, the xylem forms an X shape in the middle of the vascular bundle.

“oo” middle

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

what 4 cell types does xylem tissue consist of and are they dead or living
3.1.3(b)

A

xylem vessles (dead)
xylem tracheids (dead)
xylem fibres (dead)
xylem parenchyma (living)

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

what is the function of xylem vesslels
3.1.3(b)

A

-dead
-carry water and mineral ions from roots to all parts of the plant

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

what is the function of xylem tracheids
3.1.3(b)

A

-dead
-which also carry water and mineral ions but are slightly narrower than vessels

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

what is the function of xylem fibres
3.1.3(b)

A

-dead
-which provide support, elasticity and tensile strength to the plant

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

what is the function of xylem parenchyma
3.1.3(b)

A

-living
-which act as “packing” tissue to support the vessels

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

how does the xylem vessels being dead help support its function
3.1.3(b)

A

-Xylem vessels are dead and do not contain any cytoplasm. This minimises their resistance to the flow of water

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

what waterproof organic polymer do xylem vessels contain
3.1.3(b)

A

lignin

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

what is the function of lignin
3.1.3(b)

A

Lignin prevents water loss and also prevents the vessel from collapsing.

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

how does lignin allow flexibility
3.1.3(b)

A

lignin is deposited in spirals to allow flexibility

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

what are the small pores in the lignin layer called
3.1.3(b)

A

bordered pits

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

what is the function of bordered pits
3.1.3(b)

A

These allow water to move laterally in and out of the xylem vessel

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

which walls doesn’t xylem vessels contain
3.1.3(b)

A

no end walls between xylem vessles

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

as there are no end walls what function does this help support
3.1.3(b)

A

There are no end cell walls between xylem vessels, so xylem can transport a continuous column of water

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

what is the function of phloem
3.1.3(b)

A

-transports assimilates (product of photosynthesis) from sources to sinks

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

since plants don’t transport glucose what do they do instead
3.1.3(b)

A

Plants do not transport glucose, however. Glucose is a reducing sugar, so it’s too reactive to transport in the phloem. Instead, it is combined with fructose in a condensation reaction to form sucrose.

Sucrose is more soluble so can be transported in the sap
Sucrose is metabolically inactive so removed during transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what forms the phloem sap
3.1.3(b)

A

Sucrose, along with other organic molecules to be transported (e.g. amino acids) dissolves in water in the phloem to form phloem sap.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what two cells does phloem tissue contain
3.1.3(b)

A

· Sieve tube elements, which stack end-to-end to form sieve tubes
· Companion cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

as sieve tube elements have no nucleus and very little cytoplasm what does this leave space for
3.1.3(b)

A

· No nucleus and very little cytoplasm, leaving space for sap to flow and reducing resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what are the holes in the end wall of sieve tube elements called
3.1.3(b)

A

sieve plates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the function of sieve plates
3.1.3(b)

A

allow the sap to move from one sieve tube element to the next

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

why do companion cells contain many mitochondria
3.1.3(b)

A

Many mitochondria to produce ATP by aerobic respiration. ATP is needed for loading the phloem with sucrose, which involves active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

how are sieve tube elements directly linked to companion cells
3.1.3(b)

A

by plasmodesmata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is plasmodesmata
3.1.3(b)

A

Plasmodesmata are gaps in cell walls through which cytoplasm is continuous.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what is transpiration
3.1.2(c)

A

Transpiration is the diffusion of water vapour out of the plant through the stomata in the leaves

34
Q

why does the stomata open
3.1.2(c)

A

open to allow gas exchange for photosynthesis.

35
Q

what is transpiration
3.1.2(c)

A

Transpiration therefore is a consequence of plants’ need to exchange gases, especially carbon dioxide, for photosynthesis.

36
Q

how does transpiration occur
3.1.2(c)

A
  1. Water enters a leaf from the xylem, and moves by osmosis into the cells of the spongy mesophyll.
  2. Water evaporates from the cell walls of the spongy mesophyll, into the air spaces.
  3. Water vapour diffuses from the spongy mesophyll air spaces, through stomata, and out of the plant.
37
Q

how does water move when it leaves the plant
3.1.2(c)

A

Because the water is a gas at the point it leaves the plant, it moves by diffusion, NOT OSMOSIS. This means that the water vapour is moving down a water vapour concentration gradient, and NOT a Ψ gradient.

38
Q

how does light intensity affect transpiration rate
3.1.2(c)

A

When light shines on a plant, its stomata open to allow carbon dioxide to diffuse in for photosynthesis. Higher light intensity = more stomata open = greater rate of transpiration

39
Q

how does water availability affect transpiration rate
3.1.2(c)

A

If not much water is available, plants produce a hormone called ABA which causes the guard cells to close the stomata. The rate of transpiration would decrease.

40
Q

how does temperature affect transpiration rate
3.1.2(c)

A

A higher temperature will cause water to evaporate more easily and also cause water vapour to diffuse more quickly, so the rate of transpiration will increase.

41
Q

how does humidity affect transpiration rate
3.1.2(c)

A

High humidity means the air has a high concentration of water vapour. This will reduce the water vapour concentration gradient between the air spaces in the leaf and the outside. The rate of transpiration will therefore decrease

42
Q

how does wind affect transpiration rate
3.1.2(c)

A

Air movement outside the leaf will carry away water vapour that has just diffused out of the leaf. This maintains a high water vapour concentration gradient and so maintains a high rate of transpiration.

43
Q

what does a potometer do
3.1.2(c)

A

A potometer is a piece of equipment that is used to measure the rate of water uptake by a plant.

44
Q

what is the main assumption when using a potometer
3.1.2(c)

A

All the water taken up by the plant is transpired and none of it moves into cells or is used for photosynthesis

45
Q

how is each capillary tube filled
3.1.3(c)

A

The capillary tube is filled with water with a small air bubble inside. The distance moved by the air bubble is measured.

46
Q

once you measure the distance moved by the air bubble what can you do next
3.1.3(c)

A

measure volume of cylinder (pi x r^2)
this allows you to calculate volume of water taken up

47
Q

how do you calculate rate of water uptake
3.1.3(c)

A

Rate of water uptake = volume of water taken up (mm3) ÷ time taken (min) = mm3 min-1

48
Q

how do you calculate rate of water uptake per 1mm of leaf area
3.1.3(c)

A

Rate of water uptake per 1mm of leaf area = rate (mm3min-1) ÷ leaf area in mm2 = mm3min-1mm-2

49
Q

how do you calculate leaf area
3.1.3(c)

A

draw leaf on graph paper then double it for the total surface area of the leaf
-ensure you flatten the leaf

50
Q

why is it useful to calculate water uptake per 1mm of leaf area
3.1.3(c)

A

It’s useful to calculate rate per mm2 of leaf area because you can then make comparisons between different species with different leaf areas

51
Q

what are some practical precautions you have to take when setting up a potometer
3.1.3(c)

A

Set up underwater and cut stem underwater to avoid air entry, dry the leaves so water vapour can diffuse out of the stomata, cut stem at an angle to give high surface area for water uptake

52
Q

why do you have to keep control over variables
3.1.3(c)

A

Keep all relevant variables controlled so that the investigation is valid

53
Q

how do you calculate volume of water take up
3.1.3(c)

A

use volume of a cylinder (pi x r^2 x l)

54
Q

what is the transpiration stream
3.1.3(d)

A

The transpiration stream is the movement of water from the soil, into the roots, then up the stem, then out of the plant through the stomata in the leaves.
-continous flow of water out the stomata

55
Q

what do the long hair extensions in the root hair cell increase
3.1.3(d)

A

-the SA of the root hair cell
The root hair cells actively transport mineral ions into the cell from the soil, creating a more negative Ψ inside the cell. Water then enters the root hair cells by osmosis down the Ψ gradient

56
Q

what are the two ways water moves towards the xylem
3.1.3(d)

A

-the apoplast pathway
-the symplast pathway

57
Q

what is the apoplast pathway
3.1.3(d)

A

where water molecules diffuse within and between the cell walls, without entering cells
-forces water to pass through plasma/ cell surface membrane

58
Q

what is the symplast pathway
3.1.3(d)

A

where water molecules diffuse from one cell to the next through the cytoplasm and plasmodesmata

59
Q

what is the vascular bundle protected by
3.1.3(d)

A

The vascular bundle is protected by a layer of cells called the endodermis

60
Q

what do the endodermis cell walls contain and what does this form
3.1.3(d)

A

The endodermis cell walls contain a band of waterproof suberin (similar to lignin), which forms a structure called the Casparian strip

61
Q

what is the function of the casparian strip
3.1.3(d)

A

The waterproof Casparian strip in the endodermis stops the water molecules from being able to continue through the apoplast pathway, and they are forced into the symplast pathway before they enter the xylem

62
Q

what are the three processes that help water move up the stem
3.1.3(d)

A

-root pressure
-transpiration pull
-capillary action

63
Q

how does root pressure help pull water up the stem
3.1.3(d)

A

Water moves into xylem in roots increasing hydrostatic pressure, pushing water a few metres up the stem

64
Q

what is the cohesion-tension theory
3.1.3(d)

A

Water molecules H bond to each other which is cohesion, and as water molecules diffuse out of stomata they create tension that pulls a continuous column of water up the xylem

65
Q

what happens if the water column was broken by an air bubble
3.1.3(d)

A

If the water column becomes broken by an air bubble, then cohesion is broken and tension can no longer pull the column up the plant. In this case, water would move through the bordered pits into a xylem vessel where the water column was unbroken.

66
Q

how does capillary action move water up the stem
3.1.3(d)

A

Water molecules H bond to lignin, helping them to climb up the xylem vessel

67
Q

how does water move out of leaves
3.1.3(d)

A

· Water molecules move out of xylem and into spongy mesophyll cells by osmosis

· Water molecules then move out of spongy mesophyll cells by osmosis into the cell wall

o This makes the Ψ in the spongy mesophyll cell more negative, which ensures that water continues to enter spongy mesophyll cells by osmosis from the xylem

· Water molecules evaporate from the spongy mesophyll cell walls into the air spaces

· Water vapour molecules diffuse from the air spaces out through the stomata into the outside air

68
Q

what are xerophytes
3.1.3(e)

A

plant that have adapted through natural selection to live in conditions with low water availability

69
Q

how is marram grass adapted (5)
3.1.3(e)

A

· Rolled leaves so that air is trapped inside; this reduces the water vapour concentration gradient

· Thick waxy cuticle on outer side of rolled leaf to reduce evaporation

· Stomata are only on the inner surface

· Stomata are in hairy pits in the lower epidermis, which allows water vapour to build up in the pits and reduces the water vapour concentration gradient

· Dense spongy mesophyll with few air spaces so water doesn’t evaporate as easily

70
Q

how are cacti adapted
3.1.3

A

· Cacti are succulents – they store water in their stems which become fleshy and swollen

· Leaves are reduced to spines reducing the surface area and number of stomata for transpiration

· Stem is green to allow photosynthesis even without proper leaves

· Roots are wide-spread and shallow to maximise uptake of any rain that does fall

· Also have a large tap root that extends deep underground, to maximise water uptake from groundwater

71
Q

what are the other adaptations of xerophytes
3.1.3(e)

A

· Accumulate ions inside the spongy mesophyll cells, so that water tends to move into spongy mesophyll cells by osmosis instead of out into the air spaces

· Leaf surfaces covered in silvery hairs to reflect light, which reduces leaf temperature and so lowers the rate of transpiration

72
Q

what are hydrophytes
3.1.3(e)

A

plants that live in water

73
Q

what are the adaptations hydrophytes
3.1.3(e)

A

· Many large air spaces in the leaves, which help to keep the leaf afloat

· Air spaces in the stem (aerenchyma) which allows oxygen to diffuse quickly to the roots for aerobic respiration

· Stomata are located on the upper epidermis so that gas

exchange with the air is still possible

74
Q

What is translocation
3.1.3(f)

A

transport of assimilates from sources to sinks

75
Q

what is a source
3.1.3(f)

A

A part of the plant that loads assimilates into the phloem sieve tubes is called a source
eg-the leaves

76
Q

what is a sink
3.1.3(f)

A

A part of the plant that removes assimilates from the phloem sieve tubes is called a sink
eg-roots, or a flower.

77
Q

what are the three steps involved in translocation
3.1.3(f)

A

· Active loading of sucrose into the companion cells from source cells

· The creation of hydrostatic pressure gradients in the sieve tubes

· Unloading of sucrose into sink cells

78
Q

two steps to actively transport sucrose into companion cells
3.1.3(f)

A
  1. H+ is actively transported out of the companion cells, creating an H+ concentration gradient
  2. H+ and sucrose are co-transported from source cells into companion cells, using the H+ concentration gradient.
79
Q

hydrostatic pressure gradients in sieve tubes
3.1.3(f)

A
  1. Sucrose diffuses from companion cells into sieve tube elements through plasmodesmata.
  2. The Ψ in the sieve tube element becomes more negative.
  3. Water moves from a nearby xylem vessel into the sieve tube elements, increasing the hydrostatic pressure in the sieve tube near the source.
  4. Phloem sap flows towards sinks, down a hydrostatic pressure gradient
80
Q

unloading at sink cells
3.1.3(f)

A
  1. Sucrose diffuses from sieve tube elements into sink cells through plasmodesmata
  2. The Ψ in the sieve tube element becomes less negative
  3. Water moves from the sieve tube element into a nearby xylem vessel, reducing the hydrostatic pressure in the sieve tube near the sink.
  4. Inside sink cells, sucrose is immediately converted back to glucose and used for respiration or stored as starch, maintaining the sucrose concentration gradient
81
Q

explain the role of osmosis in plant support

A

-water enters the vacuole
-pressure against cell wall (turgor pressure)
-turgid cells support plant

Year 1 biology (25 decks)

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