transport in plants

Question 1

4 adaptations of xerophytes

Answer 1

1sunken stomata
trap water. vapour and protect it from wind movement
reduces wp between mesophyll cells and air spaces
2hinge cells
shrink when flaccid causing leaves to roll reducing sa exposed to wind and trapping water vapour
3hair/spines
block wind reduce rate of evaporation
4thickens waxy cuticle

Question 2

xerophytes

Answer 2

plants that live in places where water is in short supply and have evolved a range of adaptations to be able to survive in these conditions

Question 3

parenchyma cells

Answer 3

isodiametric cells packed tightly
mechanical support
found in cortex

Question 3

features of dicotyledons

Answer 3

12 seeds
2petals in multiples of 4/5
3vascular bundles arranged in concentric circles
4net like veins

Question 4

collenchyma cells

Answer 4

no intercellular space
extra cellulose in corners of cells for mechanical strength
in cortex below epidermis

Question 5

sclerenchyma

Answer 5

lignified walls- mechanical strength
found in non growing regions of plant

Question 6

translocation

Answer 6

1 h+ ions actively pumped out of companion cells
2 go down concentrating gradient back into companion cell via co-transporter cell taking sucrose with them
3 sucrose goes through plasmodesmata and water is drawn into sieve tube increasing hydrostatic pressure
4 movement down a pressure gradient to the sink

Question 7

xylem 4 features

Answer 7

1 lignified cells, impermeable to water, once h2o enters it cant leave
2 xylem is dead, no organelles,
3 elongated cells attached end to end with no one walls for continuous structure
4 pits where cell wall is thinner allowing water to move sideways

Question 8

phloem features

Answer 8

companion cells
no nucleus, few organelles space for sap to flow
elongated

Question 9

why is sugar transported as sucrose

Answer 9

it is not a reducing sugar and will not reduce other chemicals

Question 10

why does the phloem need companion cells

Answer 10

no mitochondria but need atp energy for active transport so companion cells provide metabolic support

Question 11

hairs and pit in xerophytes

Answer 11

trap moist air reducing water vapour potential

Question 12

symplast pathway

Answer 12

water enters cytoplasm through plasma membrane and passes from cell to cell via plasmodesmata

Question 13

apoplast pathway

Answer 13

water moves through water filled spaces between cellulose molecules in cell walls. Water doesn’t pass through any plasma filled membranes so it can carry mineral ions and salts

Question 14

what causes change from apoplast to symplast pathway

Answer 14

at endodermis there is a layer of Suberin called casparian strip

Question 15

water moving up xylem

Answer 15

water potential from loss of water
root pressure from mineral ions entering xylem and bringing water with them
cohesion

Question 16

transpiration

Answer 16

evaporation of water from the leaves via open stomata consequence of plant needing to exchange oxygen and carbon dioxide