3.1.3 transport in plants Flashcards

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1
Q

list the features of a dicotyledonous root

A

epidermis
cortex
root hair with meristem and root cap
endodermis
casparian strip
pericycle
xylem and phloem

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2
Q

list the features of a dicotyledonous stem

A

epidermis
cortex
xylem - vascular bundle
cambium
pith

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3
Q

list the features of a dicotyledonous leaf

A

waxy cuticle
upper epidermis
palisade cell layer
spongy layer
vascular bundle
lower epidermis
guard cells + stomata

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4
Q

what is transpiration

A

loss of water vapour from stems and leaves due to evaporation

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5
Q

what factors affect transpiration rate

A

light intensity
relative humidity
temperature
movement of air

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6
Q

how do we measure transpiration rate

A

potometer - movement of air bubble along cylinder due to water evaporation
rate = volume/time

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7
Q

how do you measure the volume of a cylinder

A

πr² x length

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8
Q

what is a mass potometer

A

plastic wrap around bottom to prevent evaporation from soil and place pot on balance
mass decreases over time due to transpiration

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9
Q

explain the process of transpiration

A

water evaporates from leaf cells, decreasing water potential
water moves from xylem into leaf cells via osmosis
as water moves into leaf cells it pulls water molecules in xylem behind it upwards due to cohesive forces
water moves into root hair cell by osmosis to replace water that’s moved up the xylem
as water moves through plant it helps transport minerals dissolved in it towards leaves

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10
Q

how do mineral ions enter a plant

A

by active transport into the root hair cells which causes cell to have a lower water potential than soil

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11
Q

how does water move into a root hair cell

A

by osmosis because it goes from a high water potential in soil to low water potential in root hair cell (down water potential gradient)

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12
Q

what does symplastic mean

A

water moves through cytoplasm by osmosis down the water potential gradient from root hair cell to xylem

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13
Q

what does apoplastic mean

A

water moves through cell walls due to cohesive forces like capillary action
stops at endodermis as casparian strips act as a barrier

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14
Q

what is translocation

A

movement of sucrose from cells where sugars are made (source) to cells that need them (sink)

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15
Q

what is the mass flow hypothesis

A

photosynthesis produces glucose (makes sucrose when added to fructose)
sucrose dissolves to phloem via symplast pathway and companion cells
sucrose levels increase so water potential decreases
water moves by osmosis from xylem
increases water levels which increases hydrostatic pressure so there’s a pressure gradient between source and sink
sucrose moves down gradient and diffuses into sink so water potential of phloem increases and water leaves phloem by osmosis

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16
Q

what is active loading for

A

sucrose transported by the apoplastic pathway

17
Q

describe the process of active loading

A

active transport of H+ out of cytoplasm
high H+ concentration out of cell#
H+ diffuses down concentration gradient - sucrose is cotransported
sucrose in cytoplasm

18
Q

what are xerophytes

A

plants that have evolved to live in condition where water is very scarce

19
Q

what are the adaptations of cacti

A

leaves replaced with spikes
photosynthesis occurs in stem
stomata in stem surface sunk into pits - only open t night
spines to trap moist air
thick waxy cuticle
long shallow roots or deep roots for storage

20
Q

what are the adaptions of marram grass

A

leaves roll into tube with stomata inside traps moist air
thick waxy cuticle
long roots deep to find water or shallow to retain water in sand