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Bio Module 3 > Transport in plants 3.3 > Flashcards

Transport in plants 3.3 Flashcards

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1
Q

What kind of plants is this topic based on?

A

Herbaceous dicotyledonous plants

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2
Q

What are herbaceous dicotyledonous plants?

A

Plants with a non woody stem that produce two leaves when germinating

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3
Q

What is the meristem?

A

a layer of dividing cells

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4
Q

Wh at is the vascular tissue?

A

It consists of cells specialised for transporting fluids by mass flow

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5
Q

Why do plants have transport systems?

A

To move water and minerals from the roots to the leaves and to move sugars from the leaves to the rest of the plant

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6
Q

Why can plants not just solely use diffusion?

A

Their metabolic demands are too high for diffusion to be able to supply the substances at a sustainable rate
(SA:V is to small to be sustainable)

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7
Q

Do bigger organisms have a higher or smaller SA:V?

A

Smaller

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8
Q

What are vascular plants?

A

Plants with xylem and phloem

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9
Q

What substances are transported around plants?

A
  • water
  • inorganic ions
  • sucrose
  • CO2
  • O2
  • nutrients
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10
Q

How are the xylem and phloem arranged in a stem?

A

Around the edge of the stem with the phloem on the outside, xylem on the inside and cambium in the middle

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11
Q

How are the xylem and phloem arranged in a root?

A

In the middle of the root with the xylem in an cross shape in the middle and the phloem in the arms of the cross

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12
Q

How are the xylem and phloem arranged in a leaf?

A

Found along the midrib of the leaf with the xylem on top and the phloem on the bottom

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13
Q

What is the structure of the xylem?

A

The ligning in the cell walls makes the cells waterproof which makes everything in the cell break down due to no water including the end walls forming a dead hollow tube

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14
Q

What is the function of the xylem?

A

To carry the water and dissolved minerals around the plant

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15
Q

What are the adaptations of the xylem?

A
  • made from dead aligned end to end to form a hollow column
  • tubes are norrow so that the water column does not break
  • the ligning deposit in the walls in spiral so it can stretch as the plant grows
  • no nucleus or cytoplasm
  • no cross walls
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16
Q

What is the structure of the phloem?

A
  • Companion cells have dense cytoplasm with a large nucleus and lots of mitochondria
  • sieve tube elements contain a thin layer of cytoplasm and a perferated sieve plate
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17
Q

What is the function of the phloem?

A

Used to transport assimilates around the plant (sucrose and amino acids)

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18
Q

What do the sieve tube elemts do?

A

They contain preferated cross walls called sieve plates which allows movement of the sap from one element to the next

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19
Q

How are the sieve tube elements adapted?

A

They contain no nucleus and very little cytoplasm leaving space for mass flow

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20
Q

What do the companion cells do?

A

They carry out the metabolic processes needed to load assimilates actively into sieve tubes

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21
Q

How are companion cells adapted?

A
  • they contain many mitochondria to produce ATP needed for active processes
  • large nucleus
  • dense cytoplasm
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22
Q

What is callose?

A

A complex carbohydrate

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23
Q

What does callose do?

A

It blockes the pores in the sieve plates to prevent the loss of sap and inhibits the transmissions of pathogens

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24
Q

Why are there non lignified pits in the xylem?

A

To allow for lateral movement of water

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25
Q

What colour do xylem stain?

A

Red

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26
Q

How are companion cells and sieve tube elements linked?

A

Plasmodesmata links the cytoplasm

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27
Q

Does water move up or down the water potential gradient?

A

Down

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28
Q

What does it mean when a cell is plasmolysed?

A

The plasma membrane has pulled away from the cell wall

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29
Q

What is apoplast pathway for the movement of water?

A

When water moves through the cell walls and intracellular spaces not crossing any membranes

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30
Q

What is symplast pathway for the movement of water?

A

When water moves through the cytoplasm and passes through the plasmodesmata

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31
Q

What is vacuolar pathway for the movement of water?

A

When water moves through the vacuole aswell as the cytoplasm

32
Q

What happens if a cell is placed in a solution that has a higher water potential than the contents inside?

A

There is anet movement of water into the cell, due to osmosis, down the water gradient making the cell become turgid

33
Q

What is pressure potential?

A

The water inside the cell starts to exert pressure on the cell wall

34
Q

What happenes as the pressure potential builds up?

A

The influx of water decreases

35
Q

What happens if a cell is placed in a solution that has a lower water potential than the contents inside?

A

There is a net movement of water out of the cell, due to osmosis, down the water potential gradient which makes the vacuole and cytoplasm shrink causeing the cell to become flaccid

36
Q

What happens the plasma membrane separates from the cell wall?

A

Plasmolysis

37
Q

What is plasmodesmata?

A

Gaps in the cell wall conaining cytoplasm that connects two cells

38
Q

What is the casparian strip made out of?

A

Suberin (waxy lipids)

39
Q

Where is the casparian strip found?

A

In the cell walls of the cells of the endodermis

40
Q

What does the casparian strip do?

A

Forces all the water to pass through the cytoplasm before reaching the xylem as a checking mechanic

41
Q

What are the tree ways in which water travels up the plants?

A
  • root pressure
  • transpiration pull (cohesion)
  • capillary action (adhesion)
42
Q

What is transpiration?

A

Water loss from the plants leaves and stems via diffusion and evaporation

43
Q

What is the transpiration stream?

A

The movement of water from the roots to the leaves where it is lost to the environment by evaporation

44
Q

What is the importance of transpiration?

A
  • transports mineral ions up the plant
  • maintains cell turgidity
  • supplies water for growth, cell elongation and photosynthesis
  • supplies water to evaporate and keep the plant cool
45
Q

How does water move from the xylem to the spongey mesophyll?

A

The SM have a lower water potential so the water moves into the SM down the water potential gradient via osmosis?

46
Q

What is the order of water movement in the leaf?

A
  • xylem
  • spongey mesophyll
  • air gaps
  • stomata
  • evironment
47
Q

What are the precautions when setting up a potometer?

A
  • set apparatus up underwater
  • cut stem underwater
  • dry leaves
  • add rubber tubing
  • seal connections with pertolium jelly
48
Q

What are the factors affecting the rate of transpiration?

A
  • light availibility
  • humidity
  • air flow
  • temperature
  • water availability
49
Q

How does light intensity affect transpiration?

A

Higher light intensity increases the transpiration rate as in light stomata open to allow gaseous exchange

50
Q

How does temperature affect transpiration?

A
  • higher temp increases rate of transpiration
  • increases rate of evaporation
  • increases rate of diffusion as molecules have more kinetic energy
  • decreases water vapour potential in the air
51
Q

How does relative humidity affect transpiration?

A
  • the higher the humidity the lower the transpiration rate
  • smaller water vapour potential gradient
52
Q

How does air flow affect transpiration?

A
  • as air flow increases transpiration will increase
  • maintains high water vapour potential gradient
53
Q

How does water availability affect transpiration?

A
  • as water availability decreases transpiration decreases
  • when there is insufficient water in the soil the stomata will close
54
Q

How do you use a potometer?

A

Measure the distance covered by the bubble in a set period of time then find out the rate of transpiration

55
Q

What does a potometer measure?

A

The volume of water uptaken

56
Q

What is a xerophyte?

A

Plants that live in areas where water loss via transpiration is greater than water taken up by roots

57
Q

What is a hydrophyte?

A

A plant that is partially or completely submerged in water and has problems with CO2 uptake

58
Q

What is a mesophyte?

A

Plants that take up sufficient water to replace water lost by transpiration

59
Q

What are the adaptations of cactuses?

A
  • thick small leaves
  • spines instead of leaves
  • thick waxy cuticle
  • hairs and spines trap a layer of air
  • stomata in sunken pits
  • can store water in swolen stems
60
Q

What are the adaptations of marram grass?

A
  • thick waxy cuticle
  • no stomata on the outside
  • thick cell walls
  • stomata in sunken pits
  • hinge cells that collapse in dry conditions causing the leaf to curl up
  • hair traps layer of air
61
Q

What are the adaptations of water lillies?

A
  • no waxy cuticle
  • stomata on top of the leaf
  • air pockets for bouyancy
  • wide flat leaves
  • less xylem and lignin
  • reduced structure to the plant as water supports it
  • large SA of roots underwater
62
Q

What is translocation?

A

The movement of assimilates around a plant

63
Q

What are assimilates?

A

sugars, amino acids and other substances that the plant might have made

64
Q

What direction does translocation happen in?

A

Bidirectionally

65
Q

Does translocation require energy?

A

Yes, ATP is needed for the active transport

66
Q

What are the steps in phloem loading?

A
  • H+ ions are actively pumped out of the companion cells
  • facilitated diffusion allows H+ ions back in if they contain sucrose
  • sucrose diffuses into the sieve tube elements through the plasmodesmata
  • water potential decreases so water moves into the phloem
67
Q

What is the name of the specialised carrier protein that is involved in phloem loading?

A

Cotransporter

68
Q

What is a sink?

A

They use assimilates for storage and growth and take them out of the phloem

69
Q

What is a source?

A

Provides and produces assimilates for the plant and inputs them into the phloem

70
Q

What are the steps in mass flow in the phloem?

A
  • sucrose actively move into the sieve tube elements
  • water moves in aswell due to decreased water potential
  • this increases the hydrostatic pressure in the phloem so the water moves to decrease the pressure
  • assimilates are actively moved out of the sieve cells
71
Q

What is adhesion?

A

The attraction between water molecule and the walls of the xylem vessel

72
Q

What is cohesion?

A

The attraction between water molecules caused by hydrogen bonds

73
Q

What is root pressure?

A

The action of the endodermis moving minerals into the medulla and xylem by active transport draws water into the medulla by osmosis, pressure in the roots increases and forces the water into the xylem

74
Q

What is transpiration pull?

A

As water molecules are lost at the leaves due to transpiration it pulls up the column as one chain due to the cohesion between molecules

75
Q

What is capillary action?

A

Bio Module 3 (3 decks)

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