nutrition and transport Flashcards

1
Q

stomata

A

microscopic pore
gas exchange
about 90% plant water loss is through stomata

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2
Q

turgor

A

cannot take up more water

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3
Q

wilting

A

net water loss

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4
Q

transpiration

A

keeps plant cool
transport route:root to shoot
cooling prevents cellular damage to proteins, lipids and DNA

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5
Q

how do plants balance transpiration vs. CO2 uptake ?

A

environmental plasticity
regulation of the stomata (opening & closing)
genetic adaptions (c4 and CAM)

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6
Q

opening stomata

A

Swelling guard cells

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7
Q

closing stomata

A

shrinking guard cells

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8
Q

how do stomata take water in?

A

Potassium salt attracts water. Salt is lost to neighbouring cells, therefore water is lost and stomata shrink

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9
Q

stoma opening

A

change in membrane potential over membrane. Potassium uptake through K+ channels in membrane.
passive water uptake through aquaporins in membrane.
Swelling/shrinking= change in aperture

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10
Q

when is stoma mostly closed

A

in the dark (except CAM plants)

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11
Q

what regulates the stoma ?

A

the circadian clock

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12
Q

when do stoma open?

A

when internal CO2 is low

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13
Q

when do stoma close?

A

when turgor leaf decreases

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14
Q

chemiosmotics

A

leaf movements

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15
Q

how do plants get mineral nutrients ?

A

chemical elements absorbed from soil as inorganic ions

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16
Q

how much of the plants fresh weight is water ?

A

80-90%

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17
Q

how much of a pants dry weight is organic material?

A

96%

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18
Q

how much of a plants dry weight is inorganic material?

19
Q

Essential macronutrients

A

Carbon, oxygen, hydrogen, phosphorus, sulphur, potassium, calcium and magnesium.

20
Q

essential micronutrients

A

Chlorine, iron, manganese, boron, zinc, copper, nickel, molybdenum

21
Q

deficiency

A

below optimal

22
Q

toxicity

A

super-optimal, too many essential nutrients

23
Q

Nutrient uptake by roots

A

Absorption of nutrients in the root hair zone.
extensions of epidermal cells
large surface area
permeable epidermis

24
Q

mycorrhizae

A

symbiotic structures made up of plant roots and fungal hyphae

25
Apoplast
Continuum formed by extracellular spaces in matrix of cells.
26
where is the apoplastic route blocked
endodermis
27
symplast
continuum of cytoplasm connected by plasmodesmata
28
selective uptake of nutrients into symplast
Channels selectively enable ions to cross membranes into cells. membrane potential is driving force inside cell more negative than outside
29
transporters and co-transporters of molecules
channels or channel proteins create a hydrophilic channel through the cell membrane, facilitating the transport of molecules down an electro -chemical gradient
30
endodermis
selective passage, barrier blocking apoplast
31
casparian strip
belt of waxy material in cell walls of endodermal cells blocks apoplastic route forces water and nutrients through symplast.
32
stele
tissues inward from endodermis. discharge of water and nutrients in vascular system
33
xylem
dead when functional cell walls
34
what is the driving force of xylem transport
root pressure transpirational pull
35
root pressure
osmotic forces create root pressure high salt in stele low salt in cortex
36
guttation
root pressure pushes excess water out through leaves
37
transpirational pull
creates negative pressure. Cohesion between water molecules transmits pull from leaves to roots: hydrogen bonds, requires uninterrupted chain of water
38
phloem transport
transports sugars, amino acids and hormones. Main transport sugar is sucrose
39
Phloem flow from source to link
source: where sugar is produced sink: consumer of sugar
40
phloem structure
sieve tube member, nucleus , companion cell and sieve plate
41
sieve tube
for transport. aligned, connected, connection sieve plate. are alive but lack nucleus and ribosomes
42
companion cell
linked through plasmodesmata
43
mechanism of phloem transport
at source: sugar accumulation in sieve tube passive uptake water generation positive pressure. at sink: sugar removal from sieve tube passive loss water decrease pressure