nutrition and transport

Question 1

stomata

Answer 1

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

Question 2

turgor

Answer 2

cannot take up more water

Question 3

wilting

Answer 3

net water loss

Question 4

transpiration

Answer 4

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

Question 5

how do plants balance transpiration vs. CO2 uptake ?

Answer 5

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

Question 6

opening stomata

Answer 6

Swelling guard cells

Question 7

closing stomata

Answer 7

shrinking guard cells

Question 8

how do stomata take water in?

Answer 8

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

Question 9

stoma opening

Answer 9

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

Question 10

when is stoma mostly closed

Answer 10

in the dark (except CAM plants)

Question 11

what regulates the stoma ?

Answer 11

the circadian clock

Question 12

when do stoma open?

Answer 12

when internal CO2 is low

Question 13

when do stoma close?

Answer 13

when turgor leaf decreases

Question 14

chemiosmotics

Answer 14

leaf movements

Question 15

how do plants get mineral nutrients ?

Answer 15

chemical elements absorbed from soil as inorganic ions

Question 16

how much of the plants fresh weight is water ?

Answer 16

80-90%

Question 17

how much of a pants dry weight is organic material?

Answer 17

96%

Question 18

how much of a plants dry weight is inorganic material?

Answer 18

4%

Question 19

Essential macronutrients

Answer 19

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

Question 20

essential micronutrients

Answer 20

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

Question 21

deficiency

Answer 21

below optimal

Question 22

toxicity

Answer 22

super-optimal, too many essential nutrients

Question 23

Nutrient uptake by roots

Answer 23

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

Question 24

mycorrhizae

Answer 24

symbiotic structures made up of plant roots and fungal hyphae

Question 25

Apoplast

Answer 25

Continuum formed by extracellular spaces in matrix of cells.

Question 26

where is the apoplastic route blocked

Answer 26

endodermis

Question 27

symplast

Answer 27

continuum of cytoplasm connected by plasmodesmata

Question 28

selective uptake of nutrients into symplast

Answer 28

Channels selectively enable ions to cross membranes into cells.
membrane potential is driving force
inside cell more negative than outside

Question 29

transporters and co-transporters of molecules

Answer 29

channels or channel proteins create a hydrophilic channel through the cell membrane, facilitating the transport of molecules down an electro -chemical gradient

Question 30

endodermis

Answer 30

selective passage, barrier blocking apoplast

Question 31

casparian strip

Answer 31

belt of waxy material
in cell walls of endodermal cells
blocks apoplastic route
forces water and nutrients through symplast.

Question 32

stele

Answer 32

tissues inward from endodermis.
discharge of water and nutrients in vascular system

Question 33

xylem

Answer 33

dead when functional
cell walls

Question 34

what is the driving force of xylem transport

Answer 34

root pressure
transpirational pull

Question 35

root pressure

Answer 35

osmotic forces create root pressure
high salt in stele
low salt in cortex

Question 36

guttation

Answer 36

root pressure pushes excess water out through leaves

Question 37

transpirational pull

Answer 37

creates negative pressure.
Cohesion between water molecules transmits pull from leaves to roots: hydrogen bonds, requires uninterrupted chain of water

Question 38

phloem transport

Answer 38

transports sugars, amino acids and hormones. Main transport sugar is sucrose

Question 39

Phloem flow from source to link

Answer 39

source: where sugar is produced
sink: consumer of sugar

Question 40

phloem structure

Answer 40

sieve tube member, nucleus , companion cell and sieve plate

Question 41

sieve tube

Answer 41

for transport. aligned, connected, connection sieve plate.
are alive but lack nucleus and ribosomes

Question 42

companion cell

Answer 42

linked through plasmodesmata

Question 43

mechanism of phloem transport

Answer 43

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