Xerophytes

Question 1

why thick waxy cuticle

Answer 1

-10% water loss through cuticle by transpiration so thicker helps reduce water loss when little available
-evergreen plants helps retain water in hot summer + ground is frozen in winter

Question 2

why sunken stomata

Answer 2

• pits to reduce air movement to create microclimate still moist air
• the reduces the water vapour potential gradient so less transpiration.
  -Typical for marram grass, cacti and conifers

Question 3

why small number stomata

Answer 3

reduce water loss
-but reduces gas exchange

Question 4

why reduced leaf area

Answer 4

reduce sa:v ratio to minimise wate rlost by transpiration
-eg confiers have needle leaves
-barrel catus helps microclimate prevent loss

Question 5

why hairy leaves

Answer 5

• microclimate of still humid air reducing water vapour potential gradient and minimising water loss by transpiration from leaf.
  -Marram grass even has microhairs in the sunken stomatal pits.

Question 6

why curled leaves

Answer 6

confine stomata within microcimate still humid air so less diffusion water vapour out stomata
- eg marram grass

Question 7

succulents adaption?

Answer 7

store in special parenchyma tissue in stem/root
water then used in drought
eg salicornia in uk salt marsh
desert cacti

Question 8

why leaf loss

Answer 8

when water unavailable looses leafs
eg palo verde in desert trunk and branches turns green and photosynth with minimal water

Question 9

what root adaptions

Answer 9

long tap roots gain deep water stores
wide shallow roots to absorbe from large area when rain
eg giant saguaros’ roots allows 18m tall and 200yrs old
eg marram grass long vertical roots and horizontal rhizomes (stem) which allows more roots grow

Question 10

avoid the problem? how?

Answer 10

leaf loss/dormant/die
they leave seeds to germinate when rain again
-or survive as storage organs eg bulbs
-or withstand dehydration and when rain turgid and green again and recovers linked to disaccharide trehalose