2.3B Water transport Flashcards

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1
Q

what is transpiration

A

evaporation from leaves

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2
Q

what are the 3 section of water movement

A
  1. movement through roots
  2. movement through stem
  3. movement through leaf
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3
Q

what are the 2 paths that water moves through roots

A
  1. sympath pathway
  2. apoplast pathway
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4
Q

is apoplast or aeoplast faster

A

apoplast

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5
Q

what is the symplast pathway

A
  • moves through the cytoplasm of one cell, to the cytoplasm of an adjacent cell (via plasmodesmata)
  • moves across cortex via osmosis (down water potential gradient)
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6
Q

how does water move into root hair cells

A

via osmosis from soil

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7
Q

what is the apoplast pathway

A
  • water moves within cell walls + spaces between cells
  • quicker, water moves easily through cellulose fibres + less resistance to water flow
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8
Q

what is cohesion

A

when water molecules are attracted to eachother

(due to hydrogen bonds)

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9
Q

how is the apoplast pathway driven

A

by cohesion

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10
Q

how is the symplast pathway driven

A

by water potential gradient(between root hair cells and xylem)

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11
Q

what must happen before water can pass into the xylem (apoplast)

A

pass through a layer of cells: endodermis

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12
Q

what in the endodermis causes the apoplast pathway to stop

A

casparian strip

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13
Q

what is the casparian strip made of

A

Suberin (waterproof)

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14
Q

what does the casparian stip do?

A

disallow water to move via the apoplast pathway

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15
Q

how does water move after it has encountered the casparian strip

A

moves through cell membrane, into cytoplasm (becoming part of the symplast pathway)
This allows the cell membrane to choose what can enter the xylem

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16
Q

how is the water potential in the xylem lowered?

A

cells in endodermis pump ions into xylem (via active transport)

17
Q

why is water potential lowered in the xylem

A

triggering water to move into xylem via osmosis. this is called ROOT PRESSURE

18
Q

what does ROOT PRESSURE require

A

ATP

19
Q

what happens to ROOT PRESSURE if a respiratory inhibitor is used

A

it stops. No ATP is being produced

20
Q

what happens to ROOT PRESSURE if oxygen is excluded

A

stops. no ATP