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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
Meristem in roots
Increase height of pants
26
Meristem in stem
Increases plant girth
27
Stele
Section in the middle of transverse section of dicotyledonous route – Endodermis – xylem tissue – Phloem tissue
28
Water uptake
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
29
Pith
Made from parenchyma cells | Forms inner cortex
30
Epidermis in plants
Protect moist under tissues from desiccation an invasion of pathogen
31
Translocation
Movement of dissolved Solutes ( sucrose) from sources to sinks ( tissues that need them ) through the phloem
32
What is translocation bidirectional?
Roots can act as a sink by releasing carbohydrates and also as a store depending on the time of year
33
Process of translocation
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
Mass flow
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
How does the process of translocation reoccur?
Sink remove sugar which increases water potential H2O leaves tubes keeping hydrostatic pressure low
36
Tonoplast
Membrane around cell wall
37
Function of endodermis
Controls amount of H2O coming in
38
What is the Caspian strip made of?
Suberin- Impermeable to water, lipid
39
What does Casperian strip stop?
Movement of water through the Apoplast
40
Sources to sink
Sugar moving from where it’s made to where it stored
41
Possible sinks
Seeds Fruit Meristems Fruit
42
Possible sources
Leaves Food stores in seeds Storage organs
43
How does water get up the xylem?
Root pressure Capillary action Transpirational pull H20 cannot return to cortex through apoplast therefore pressure builds up in cortex pushing H2O up xylem
44
Root pressure
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
Capillary action
H2O can rise up a narrow tube against the force of gravity
46
Cohesion
Water molecules sticking together
47
Adhesion
Attraction between water molecules and the walls of the xylem
48
Transpirational pull
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
How does water move in and exit the leaf?
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
Mesophytes
Plants adapted to a habitat with adequate water
51
Halophytes
Plants adapted to a salty habitat
52
Xerophytes
Plants adapted to dry habitats
53
Adaptions of xerophytes
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
Hydrophytes
Plants adapted to live in freshwater
55
Adaptations of hydrophytes
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
Adaptations of xylem
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
Adaptations of sieve tube elements
``` Form long tubes End walls are retained End walls contain many sieve pores Thin layer of cytoplasm Very few organelles, no Nucleus ```
58
Adaptations of companion cells
Closely associated with sieve tube elements Connected to sieve tube elements by many plasmodesmata Dense cytoplasm with many mitochondria Large Nucleus
59
Cohesion tension theory
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
Transpiration stream
Movement of water up xylem vessels from roots to leaves | Area of high hydrostatic pressure to area of low hydrostatic pressure
61
Translocation occurs through the sieve elements by.......
Mass flow
62
What gets transported in translocation?
Assimilate such as sucrose and amino acids
63
What are assimilates?
Products of photosynthesis
64
Why does the wind affect transpiration?
Favour around the stomata is blown away Reduces water vapour around stomata Create a steeper water potential gradient
65
Why is water loss from the leaves unavoidable ?
Stomata open for gas exchange for photosynthesis Photosynthesis is necessary to make sugars Water loss through the cuticle
66
Why is sucrose transported in translocation not glucose?
Soluble so can easily travel in solution | Metabolically inactive so not used during transport
67
Why does low temperature cause death of cells?
Ice forms and pieces membranes denaturing the proteins
68
Evidence for the role of active transport in root pressure
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
Evidence for cohesion tension theory
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
Evidence for translocation
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
Why is water stop from entering the apoplast through the Casparian strip?
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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