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BIOLOGY AS OCR > Chapter 3.3 Transport In Plants > Flashcards

Chapter 3.3 Transport In Plants Flashcards

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1
Q

Why do plants need a transport system ?

2

A

1- to move water and Mineral ions from roots to leaves
2-sugar from leaves to rest of plant
3-support
4-they respire

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2
Q

Why does oxygen not need to be transported ?

3

A
  • it can enter by diffusion
  • plants aren’t active
  • demand is low
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3
Q

What’s diffusion ?

3

A
  • result of random motion of particles
  • down concentration gradient
  • may move in different directions
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4
Q

What’s mass flow ?

2

A
  • particles move together

- down pressure or temperature gradient

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5
Q 
What is the distribution of Xylem in 
-root
-stem 
-leaf 
(3)
A
  • root = centre of root
  • stem = inner vascular bundle
  • leaf= upper part of vascular bundle
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6
Q 
What’s the distribution of phloem in 
-root
-stem 
-leaf 
(3)
A
  • root : near centre around Xylem
  • stem : middle of vascular bundle
  • leaf : lower part of vascular bundle
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7
Q

What are the main features of Xylem ?

4

A

1-thick lignified walls (dead)( withstand water pressure / water proof )
2-empty lumen allows easy flow
3-long straight column ( no end cell wall )
4-bordered pits to allow water to pass between vessels

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8
Q

What are the main feature of phloem?

4

A

1- living cells
2-connected via sieve tubes
3-sieve tube elements = no nucleus and thin layer of cytoplasm ( no metabolic functions )
4- companion cells - carry out all function for tube and itself ( lots of mitochondria )

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9
Q

What’s the apoplast pathway ?

1

A

Apoplast pathway - water moves through spaces in cell walls

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10
Q

What’s the Symplast pathway ?

1

A
  • water movement through cytoplasm
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11
Q

What’s the vacuolar pathway ?

1

A

Water moves Through cytoplasm and vacuoles

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12
Q

What’s water potential.

1

A

Tendency of water molecules to move from one place to anther

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13
Q

What’s the route water takes up the plant ?

3

A
  • Xylem via osmosis
  • apoplast pathway (between cell walls)
  • evaporates out of leaf via open stomata.
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14
Q

What is the importance of water transport.

4

A
  • transports mineral ions up plant
  • maintains Turgidity
  • supplies water for growth
  • supplies water that can keep plant cool when it evaporates
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15
Q

What environmental effects effect transpiration.

5

A
  • light intensity
  • Temp
  • relative humidity
  • air movement ( wind )
  • water Availability
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16
Q

What does high light intensity do to transpiration rate ?

1

A

INCREASE

Stomata opennn

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17
Q

High temp - transpiration rate?

1

A

Increases

Stomata opennnn

18
Q

HIGH humidity ? Transpiration rate?

2

A
  • reduces transpiration rate Because water potential gradient is less steep
19
Q

Windy ? Transpiration rate ?

2

A
  • more wind ( takes away water vapour so gradient is steeeep)
20
Q

how’s Transpiration rate calculated ?

A
  • VOLUME / TIME
21
Q

What’s adhesion

1

A

Attraction of water molecules to walls of Xylem

22
Q

What’s cohesion

2

A

-attraction between water molecules caused by H bonding !

23
Q

How does water enter plant ?

-3

A
  • root hair cells
  • osmosis
  • apoplast pathway
24
Q

What does the casparian strip do ?

2

A
  • block apoplast pathway

- water , dissolved mineral ions have to pass through cytoplasm

25
Q

What are the 3 processes that help water move up the stem ?

3

A
  • transpiration pull
  • root pressure
  • capillary action
26
Q

What’s root pressure?

3

A
  • active transport moves minerals into medulla and Xylem( low water potential)
    -pressure rises in medulla (packing tissue)
    Water moves from high —> low pressure
    -water is forced into Xylem = pushes water a few meters
27
Q

What’s the transpiration pull ?

4

A
  • cohesion keep water molecules in one long chain
  • molecules lost at top
  • whirl column moves up
  • PULL IS CREATED BY TENSION ( Xylem is strengthened by lignin o support this )
28
Q

What’s capillary action ?

2

A
  • ADHESION attracts water molecules to side of Xylem vessel and pull water up
29
Q

How does water leave he leaf ?

A
  • air spaces
  • stomata
  • evaporates
30
Q

What’s a xerophyte ?

1

A

Plant adapted to living in DRY conditions

31
Q

What’s a hydrophyte ?

1

A

Plant adapted to living in water or wet conditions !

32
Q

Name some adaptations of Xerophytes …

6

A
  • reduce water loss :
    1-hairs on epidermis trap moist air
    2-roll leaves - trap air
    3-thick waxy cuticle layer ( water can’t move through it )
    4-cacti = spines SA REDUCED FOR WATER LOSS
    5-Closure if stomata
33
Q

Name some adaptations of hydrophytes

5

A 
1-Air spaces ( store O2 & float )
2-stomata only present on top surface 
3-flexible leaves and stems 
4- supported by water so no rigid stem 
5- HYDRATHODES -produce water droplets which may evaporate from leaf for transpiration
34
Q

What’s a source ?

1

A

Part of plant that loads material into transport system

35
Q

What’s a sink ?

1

A

Materials are removed from transport system

36
Q

What’s translocation ?

A
  • transport of assimilates through plant
37
Q

What’s the mass flow hypothesis of phloem transport at SOURCE ?
(3)

A

1- AT SOURCE
solutes diffuse into phloem tube ( lower water potential)
2-water then follows via Osmosis ( to phloem tube )
3-at the SOURCE there is Highe pressure in phloem and Low water potential !

38
Q

What happens at the SINK in mass flow hypothesis ?

4

A

1- solutes move to sink via active transport or diffusion depending on concentration
2-water potential in phloem rises
3-water leaves phloem to XYLEM
= HIGH WATER POTENTIAL AND LOW PRESSURE

39
Q

What does the mass flow in phloem create ?

2

A
  • PRESSURE GRADIENT !
    High to low ( from source to sink )
  • pressure flow
40
Q

What’s happens in active loading in companion cells ?

7

A

1- H+ ions move out via active transport
2-high concentration H+ ion in photosynthesising cell
3-H+ move back to Companion cell via facilitated diffusion ! ( H+ brings sucrose )
4-in the companion cell sucrose levels rise !
5-then sucrose diffuse into phloem ( high to low conc)
6-the water potential in lowered
7-water moves into phloem via OSMOSIS

41
Q

Explain why large multicellular plants need a transport system ?
(2)

A
  • too small sa:v so diffusion is too small

- transport system needed to transport waste / nutrients

42
Q

What organelles yield the pigments present in the leaf ?

1

A
  • chloroplast

BIOLOGY AS OCR (12 decks)

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