gas exchange in leaf + xerophytes

wake up phill so aunt vicky leaves wales

waxy cuticle
upper epidermis
palisde mesophyll
spongy mesophyll
air space + vein
lower epidermis
waxy cuticle

role of guard cells and where are they present?

surrounding stomata in low epidermis to control their opening/closing

how does gas exchange take place at the stomata?

• CO2 diffuses in through stomata which are opened + closed by guard cells

• it diffuses through air spaces to reach palisade mesophyll

• O2 from PS diffuses out of cells via air spaces + stomata

adaptations of leaf for effective gas exchange?

thin - short diffusion pathway

many stomata close to mesophyll cells

mesophyll cell air spaces → large SA

how are xerophytes adapted to limit water loss?

• curled leaves trap moisture increasing local humidity

• hairs to trap moisture to increase humidity

• sunken stomata to trap moisture to increase humidity

• thicker cuticle to decreases evaporation

• longer root network to reach more water

how does increasing local humidity limit water loss?

decreases water potential gradient between inside + outside plant so water doesn’t leave