4.3 Gas Exchange (plants)

Question 1

gas exchange at a stomata

Answer 1

oxygen diffuses out of the stomata

carbon dioxide diffuses in through the stomata DURING THE DAY
OPPOSITE HAPPENS AT NIGHT

to reduce water loss by evaporation, stomata close at night when photosynthesis wont be occuring

Question 2

how are plant leaves adapted for gas exchange

Answer 2

Spongymesophyll layer provides large surface area
Waxy cuticle is impermeable to gas preventing excessive water loss
Lenticels(loosely arranged cells) allow gases to enter and leave

Question 3

Explain how the structure of this leaf ensures that the water potential at X remains high.

Answer 3

less transpiration because of the waxy cuticle which traps water vapour

Question 4

gas exchange and photosynthesis

Answer 4

during the day
photosynthesis is occuring faster than respiration, co2 enter, o2 out. o2 that is out is used for respiration.
at night
photosynthesis does not occur. so o2 enter, co2
but the stoma close at night to reduce water loss so o2 enters via the lenticles.