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Bio Module 3 > Transport in plants 3.3 > Flashcards

Transport in plants 3.3 Flashcards

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

What 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

They are too big, their metabolic demands are too high and their SA:V is too small for diffusion to be able to supply the substances at a sustainable rate

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7
Q

What substances are transported around plants?

A
  • water
  • inorganic ions
  • sucrose
  • CO2
  • O2
  • nutrients
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8
Q

What is cambium?

A

Layer of meristem cells that divide to produce new xylem and phloem

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9
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 a strip between them

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10
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 between the arms of the cross

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11
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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12
Q

What is the function of the xylem?

A

To carry the water and dissolved minerals from the roots to the leaves

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13
Q

What is the structure and adaptations of the xylem?

A
  • lignin impregnated walls = waterproof, strengthens vessel to prevent collapse and grows in spirals to strech as the plant grows
  • cells are dead = end walls and contents of cell decay forming a dead hollow column
  • narrow tubes = water column does not break
  • no nucleus, cytoplasm or cross walls = flow of water not impeded
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14
Q

Why are there non lignified pits in the xylem?

A

To allow for lateral movement of water

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15
Q

What is the function of the phloem?

A

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

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16
Q

What is the structure of the phloem?

A

Consists of companion cells and sieve tube elements

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17
Q

How are the sieve tube elements adapted?

A
  • no nucleus and very little cytoplasm leaving space for mass flow
  • perferated sieve plates allow movement from one element to the next
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18
Q

How are companion cells adapted?

A
  • many mitochondria to produce ATP for active processes (loading assimilants into sieve tubes)
  • large nucleus
  • dense cytoplasm
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19
Q

What is callose and what does it do?

A

A complex carbohydrate that blocks pores in the sieve plates to inhibit transmissions of pathogens

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20
Q

What colour do xylem stain?

A

Red

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21
Q

How are companion cells and sieve tube elements linked?

A

Plasmodesmata links the cytoplasm

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22
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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23
Q

What is apoplast pathway for the movement of water?

A

Water moves through cell walls and intracellular spaces, not crossing membranes

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24
Q

What is symplast pathway for the movement of water?

A

Water moves through cytoplasm and passes through plasmodesmata

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25
Q

What is vacuolar pathway for the movement of water?

A

When water moves through the vacuole and the cytoplasm

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26
Q

What is pressure potential?

A

The pressure that the water inside the cell exerts on the cell wall

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27
Q

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

A

Net movement of water into the cell, due to osmosis, down the water potential gradient (cell becomes turgid)

28
Q

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

A

Net movement of water out of the cell, due to osmosis, down the water potential gradient (vacuole and cytoplasm shrink so cell becomes flaccid)

29
Q

What happens in plasmolysis?

A

Plasma membrane separates from cell wall

30
Q

What is plasmodesmata?

A

Gaps in the cell wall conaining cytoplasm that connects two cells

31
Q

What is the casparian strip made out of and where is it found?

A
  • suberin (waxy lipids)
  • in cell walls of the cells of the endodermis
32
Q

What does the casparian strip do?

A

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

33
Q

What is the transpiration?

A

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

34
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
35
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

36
Q

What is the order of water movement in the leaf?

A
  • xylem
  • spongey mesophyll
  • air gaps
  • stomata
  • evironment
37
Q

What are the factors affecting the rate of transpiration?

A
  • light availibility
  • humidity
  • air flow
  • temperature
  • water availability
38
Q

How does light intensity affect transpiration?

A

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

39
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
40
Q

How does relative humidity affect transpiration?

A
  • the higher the humidity the lower the transpiration rate
  • smaller water vapour potential gradient
41
Q

How does air flow affect transpiration?

A
  • as air flow increases transpiration will increase
  • maintains high water vapour potential gradient
42
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
43
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

44
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
45
Q

What does a potometer measure?

A

The volume of water uptaken

46
Q

What is a xerophyte?

A

Plants adapted to live in dry conditions

47
Q

What is a hydrophyte?

A

Plants adapted to living in water or where the ground is very wet

48
Q

What is a mesophyte?

A

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

49
Q

What are the adaptations of cactuses?

A
  • thick small leaves
  • leaves reduced into spines
  • thick waxy cuticle
  • hairs and spines trap a layer of air
  • stomata in sunken pits
  • can store water in swolen stems
50
Q

What are the adaptations of marram grass?

A
  • thick waxy cuticle
  • no stomata on the outside of the leaf
  • 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
51
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
52
Q

What is translocation?

A

The movement of assimilates around a plant

53
Q

What are assimilates?

A

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

54
Q

What direction does translocation happen in?

A

Bidirectionally

55
Q

Does translocation require energy?

A

Yes, ATP is needed for the active transport

56
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
57
Q

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

A

Cotransporter

58
Q

What is a sink?

A

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

59
Q

What is a source?

A

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

60
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 an area of lower water potential to decrease the pressure and it moves the assimilants with it
  • assimilates are actively moved out of the sieve cells
61
Q

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

A
  • root pressure
  • transpiration pull (cohesion)
  • capillary action (adhesion)
62
Q

What is adhesion?

A

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

63
Q

What is cohesion?

A

The attraction between water molecules caused by hydrogen bonds

64
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

65
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

66
Q

What is capillary action?

A

Due to the adhesion of water molecules to the xylem vessels it can pull the water up the sides of the vessels

Bio Module 3 (3 decks)

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