Gas Exchange in Plants Flashcards
palisade mesophyll features and function
- elongated cells so more SA for CO2 to diffuse
- main site site of photosynthesis as contains the highest density of chloroplasts
spongy mesophyll
gas exchange surface
contains the vascular bundle
waxy cuticle
- impermeable to water
- reduce water loss by evaporation
epidermis in plant cells
- protection from mechanical damage
air space in plant cells
- gas exchange
- easier to diffuse through air (gas) than cells
stoma
- allows entry/exit of gases
- can close to reduce water loss by transpiration
guard cells
- contains chloroplasts
- allows stomata to open and close
gas exchange organ of plants
leaf
gas exchange surface in plants
stomata
xerophyte
a plant tht lives in an environment that has a limited supply of water and is adapted to survive there
4 adaptations of a cactus
- leaves end in spines - reduce SA available for stomata, so less stomata, so less SA for transpiration
- fleshy (succulent) stem - stores water
- some have thick cuticle - reduces waer loss as more impermeable to water
- shallow, widespread roots - increases SA available for water uptake
5 adaptations of marram grass
- rolled leaf - traps water molecules next to stomata, increasing humidity, reducing diffusion gradient so reducing transpiration
- leaf hairs - traps water. reducing diffusion gradient and transpiration
- sunken stomata - creates humid atmosphere outside stomata as air not moved away, reducing diffusion gradient, reducing transpiration
- fewer stomata - reduces SA for diffusion of water vapour out so reduces transpiration
- ticker waxy cuticle - reduces water loss by evaporation as more impermeable to water
at night, what is the net movement of O2 and why?
net movement in as rate of PS is greater than that of RS
in the day, what is the net movement of O2?
net movement out as rate of RS more than rate of PS
gases exchanged by plants
- O2
- CO2
- water diffusion
how to calculate SA of a leaf
- trace around leaf on graph paper
- count number of squares
- multiply by 2 (both sides)
formula for stomatal density
(mean number of stomata in field of view)/(area of field of view)
how to calculate are of field of view (4 steps)
- measure diameter of FOV in epu using epg
- convert diameter to micrometres by multiplying by conversion for that mag
3.convert from micrometres to mm by dividing by 1000
4.calculate area of FOV in mm^2 using equation of a circle
3 steps to calculate stomatal density
- count number of stomata in 3 different FOVs at x 40 mag
- calculate mean number of stomata in FOV
- calculate stomatal density (mean number/area
