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A-level Biology OCR > Unit 3 - Transport In Plants > Flashcards

Unit 3 - Transport In Plants Flashcards

1
Q

What distinguishes stems from other parts of the plant?

A

Presence of nodes and internodes

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2
Q

Role of vascular cambium?

A

Responsible for secondary growth and contains meristematic tissue

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3
Q

Functions of roots

A

Anchor the plant in the ground
Store Excess carbohydrates
Absorb water and minerals

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4
Q

Role of the Parenchyma

A

Involved in respiration, photosynthesis, storage and secretion
Heavily lignified

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5
Q

What is Collenchyna tissue made of?

A

Pectin
Cellulose
Collenchyna Cells

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6
Q

Role of Collenchyna?

A

Provide support

Expands as the stem grows

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7
Q

Role of endodermal cells?

A

Regulate the substances enter

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8
Q

What is pericycle made of?

A

Parenchyma

Sclerenchyma

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9
Q

Role of pericycle

A

Maintains meristematic activity

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10
Q

What is Xylem tissue made of?

A

Tracheids
Vessel elements
Parenchyma
Sclerenchyma

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11
Q

Embolisms

A

Air bubbles formed in plant capillaries

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12
Q

What is the cortex made of?

A

Parenchyma

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13
Q

Transpiration

A

Loss of water from leaves of a plant, occurs from the underside of the leaf, stomata.
Water moves from areas of high hydrostatic pressure to areas of low hydrostatic pressure

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14
Q

Functions of water in plants

A

Turgidity dash keep stems and leaves Richard
Photosynthesis
Enzyme reactions – metabolic processes occur in solution
Transport – ions absorbed in solution and transported in xylem

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15
Q

Apoplastic pathway

A

Water moving from soil solution to root hair and across cortex to the Xylem in the cell walls

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16
Q

Symplastic pathway

A

Water moving from soil solution to root hair and across cortex to the xylem through the cytoplasm and plasmodesmata

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17
Q

Vacuolar pathway

A

Water moving from soil solution to root hair and across cortex to the xylem through vacuoles

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18
Q

Factors affecting rate of transpiration

A

Temperature
Humidity
Light intensity
Wind

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19
Q

Lignin

A

Causes spirals in xylem

Allows cells to stretch and expand

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20
Q

Adaptations of vessel elements

A

Hollow lumen
Perforated cell ends
Lignin for rigidity

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21
Q

Casparian strip

A

Controls amount of water coming in the endodermis

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22
Q

Factors affecting transpiration

A 
Temperature
Humidity
Light intensity
Air movement
Soil water availability
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23
Q

Purpose of root hairs

A

Provide a very large surface area for uptake of water and ions

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24
Q

Why is the root tip covered by a cap of cells?

A

Protects dividing cells of the top and lubricate roots movement

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25
Q

Meristem in roots

A

Increase height of pants

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26
Q

Meristem in stem

A

Increases plant girth

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27
Q

Stele

A

Section in the middle of transverse section of dicotyledonous route

– Endodermis
– xylem tissue
– Phloem tissue

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28
Q

Water uptake

A

Water enters capillaries from soil by osmosis
Apoplast and symplast pathways
Water leaves Apoplast at endodermis and enter from symplast
Water enters xylem under root pressure then travels in the tracheids and vessel elements
Water carried to mesophyll through small veins
Evaporate in leaf air spaces and stomata

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29
Q

Pith

A

Made from parenchyma cells

Forms inner cortex

30
Q

Epidermis in plants

A

Protect moist under tissues from desiccation an invasion of pathogen

31
Q

Translocation

A

Movement of dissolved Solutes ( sucrose) from sources to sinks ( tissues that need them ) through the phloem

32
Q

What is translocation bidirectional?

A

Roots can act as a sink by releasing carbohydrates and also as a store depending on the time of year

33
Q

Process of translocation

A

Glucose formed in photosynthesis and condensed
Moves into companion cell by active transport
Reduces water permeability allowing HT water moving
Create high hydrostatic pressure – maths floor
Sucrose diffuses out of phloem to where it’s needed for growth and storage

34
Q

Mass flow

A

Assimilates enter sieve tube and lower water potential
Water enters through osmosis and increases hydrostatic pressure
Assimilate leave at sink and increase water pressure
Water leaves and lowers hydrostatic pressure
High hydrostatic pressure forces sap through vessels towards regions of low hydrostatic pressure

35
Q

How does the process of translocation reoccur?

A

Sink remove sugar which increases water potential H2O leaves tubes keeping hydrostatic pressure low

36
Q

Tonoplast

A

Membrane around cell wall

37
Q

Function of endodermis

A

Controls amount of H2O coming in

38
Q

What is the Caspian strip made of?

A

Suberin- Impermeable to water, lipid

39
Q

What does Casperian strip stop?

A

Movement of water through the Apoplast

40
Q

Sources to sink

A

Sugar moving from where it’s made to where it stored

41
Q

Possible sinks

A

Seeds
Fruit
Meristems
Fruit

42
Q

Possible sources

A

Leaves
Food stores in seeds
Storage organs

43
Q

How does water get up the xylem?

A

Root pressure
Capillary action
Transpirational pull
H20 cannot return to cortex through apoplast therefore pressure builds up in cortex pushing H2O up xylem

44
Q

Root pressure

A

Endodermis in roots uses metabolic energy to pump ions into root
Reduces water potential in xylem and medulla H2O moves across endodermis into medulla

45
Q

Capillary action

A

H2O can rise up a narrow tube against the force of gravity

46
Q

Cohesion

A

Water molecules sticking together

47
Q

Adhesion

A

Attraction between water molecules and the walls of the xylem

48
Q

Transpirational pull

A

Loss of H2O through leaves must be replaced by H2O in the xylem
H2O moves up xylem as a result of tension, created by loss of water in leaves
H2O moves out of the xylem, the whole column gets drawn up due to cohesion

49
Q

How does water move in and exit the leaf?

A

Enters through the xylem, passes through the Mesophyll and air space in spongy Mesophyll
H2O vapour collect water potential rises, when higher in the leaf

50
Q

Mesophytes

A

Plants adapted to a habitat with adequate water

51
Q

Halophytes

A

Plants adapted to a salty habitat

52
Q

Xerophytes

A

Plants adapted to dry habitats

53
Q

Adaptions of xerophytes

A

Rolled leaves – Reduces surface area
Reduced number and size of stomata – reduces diffusion
Sunken stomata - creates pockets of water vapour
Thick waxy cuticle – impermeable
Hairy leaves – traps water vapour
Dense spongy Mesophyll– smaller surface area for evaporation
Thick stem – stores water

54
Q

Hydrophytes

A

Plants adapted to live in freshwater

55
Q

Adaptations of hydrophytes

A

Arenchyma- parenchyma with many air spaces, buoyancy
Allows O2 to diffuse to roots for aerobic respiration
Reduced root system – water can directly into leaves, feathered roots hold up plant
Large thin leaves stomata on the upper surface only

56
Q

Adaptations of xylem

A

End walls removed to form long tubes
No cytoplasm or cell organelles – little resistance to flow of water
Lignified waterproofing and strengthening
Boarded pits – allow movement of water between vessels

57
Q

Adaptations of sieve tube elements

A 
Form long tubes
End walls are retained
End walls contain many sieve pores 
Thin layer of cytoplasm
Very few organelles, no Nucleus
58
Q

Adaptations of companion cells

A

Closely associated with sieve tube elements
Connected to sieve tube elements by many plasmodesmata
Dense cytoplasm with many mitochondria
Large Nucleus

59
Q

Cohesion tension theory

A

Evaporation at top of the xylem creates tension in the xylem water molecules are cohesive and form a column which is then pulled up by tension

60
Q

Transpiration stream

A

Movement of water up xylem vessels from roots to leaves

Area of high hydrostatic pressure to area of low hydrostatic pressure

61
Q

Translocation occurs through the sieve elements by…….

A

Mass flow

62
Q

What gets transported in translocation?

A

Assimilate such as sucrose and amino acids

63
Q

What are assimilates?

A

Products of photosynthesis

64
Q

Why does the wind affect transpiration?

A

Favour around the stomata is blown away
Reduces water vapour around stomata
Create a steeper water potential gradient

65
Q

Why is water loss from the leaves unavoidable ?

A

Stomata open for gas exchange for photosynthesis
Photosynthesis is necessary to make sugars
Water loss through the cuticle

66
Q

Why is sucrose transported in translocation not glucose?

A

Soluble so can easily travel in solution

Metabolically inactive so not used during transport

67
Q

Why does low temperature cause death of cells?

A

Ice forms and pieces membranes denaturing the proteins

68
Q

Evidence for the role of active transport in root pressure

A

Some poisons affect mitochondria and prevent production of ATP, when cyanide is applied to root cells, root pressure decreases
Root pressure increases with a rising temp and decreases with a fall in temperature
It’s O2 levels fall or raspatory substrates so does root pressure

69
Q

Evidence for cohesion tension theory

A

Changes in diameter of trees – when transpiration is that its highest as is the tension, diameter shrinks
When is xylem vessel is broken air is drawn in rather than water leaking out
Plant can no longer move water of the stem as continuous stream is broken

70
Q

Evidence for translocation

A

Microscopy has allowed us to see the adaptions of Companion cells active transport
If the mitochondria of companion cells are poisoned, translocation stops
Flow of sugars in phloem is 10,000 times faster than diffusion

71
Q

Why is water stop from entering the apoplast through the Casparian strip?

A

Ensures water and dissolved mineral ions have to pass into the cell through the plasma membrane so the water and ions are in the cytoplasm
Prevent water from cortex going back to Medulla

A-level Biology OCR (2 decks)

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