Plants Flashcards
What occurs in the day
Lots of photosynthesis
Taking in lots of co2 and lets out oxygen
Mainly co2 in amd o2 out (some respiration occurring)
What happens night
No photosynthesis
Oxygen in co2 out
Respiration happens all the time (day and night)
What is the light compensation point
Rate of photosynthesis = rate of respiration
Therefore there is no net movement of co2
What is the gas exchange surface in a leaf
Surface of mesophyll cells in contact with the air spaces in the leaf
Adaption of mesophyll cells
Large sa and small diffusion distance
Gas only travel from air space across single cell wall to get to the cytoplasm in the cell
Transpiration
Water evaporates from wet cell wall in contact with air spaces in the leaf
Water vapour in the air spaces moves out of the stomata and is lost by transpiration
What are xerophytes
Plants that have developed adaptions to limit water
Adaption of xerophytes
Thick cuticle
Rolling up leaves
Hairy leaves
Stomata in pits or grooves
Reduced SA:V
Xerophyte Adaption
Thick cuticle
Less water escape by transpiration
Diffusion distance increased
Xerophyte adaption
Rolling up leaves
Marram grass leaves roll themselves when transpiration rate increases
Protecting the lower epidermis from outside helps trap air within the leaf
As it becomes saturated with water the water potential gradient is reduced so less transpiration
Xerophyte adaption
Hairy leaves
Trap moist air next to leaf surface, reduces water potential between out and in the leaf so less transpiration
Xerophyte adaption
Stomata in pits or grooves
Traps moist air next to the leaf reducing water potential gradient so less transpiration
Xerophyte adaption
Reduced SA:V
Thin needles reduce SA so less diffusion so less transpiration
