Gas exchange Flashcards
what do most exchange surfaces have in common
large surface area
thin - short diffusion pathway
steep concentration gradient
how do single celled organisms exchange gases
through surface
by diffusion
why is there no need for a gas exchange system in single celled organisms
they have a relatively large surface area + short diffusion pathway
where is there a higher concentration of oxygen
in water than in the fish
where does water enter from
the mouth
where does water pass out from
the gills
what is each gill made of
thin plates
called gill filaments
what do gills provide
large surface area
what are gill filaments covered in
lamellae
what do lamellae do
increase the surface area even more
how do lamellae increase rate of diffusion
have lots of blood capillaries
thin surface layer
how do blood and water flow
in opposite directions
what is a counter - current system
blood and water flowing in opposite directions
what does a counter-current system maintain
a concentration gradient
how does the counter-current system maintain a concentration gradient
concentration of oxygen in water always higher than in blood
so as much oxygen diffuses into blood from water as possible
what are tracheae
air filled pipes
what is the function of tracheae
gas exchange
how does air move into the trachea
through pores on surface
called spiracles
how does oxygen from the air travel to cells in the insect
down the concentration gradient
how does the oxygen get to each individual respiring cell
trachea branches into tracheoles
which have thin, permeable walls
and branch off into each cell
how does carbon dioxide leave the cells?
down its concentration gradients
through the spiracles
how do insects move air in/out the spiracles
through rhythmic abdominal movement
what is the main site of exchange in plants
mesophyll cells in leaf
how are spongy mesophyll cells adapted for exchange
large surface area
through what do gases move in/out the cells
stomata
what controls the opening of the stomata
guard cells
how would guard cells control the opening of the stomata if too much water is lost
guard cells become flaccid
closing the opening
how can insects reduce water oss
close their spiracles using muscles
waterproof waxy cuticle all over body
tiny hairs around spiracles
how can plants reduce water loss
guard cells become flaccid
which closes the pore
what are xerophytes
plants adapted for life in warm, dry or windy conditions where water loss is a problem
what are some xerophytic adaptations
stomata sunk in pits
layer of hairs on epidermis
curled leaves with stomata on inside
reduced number of stomata
waxy, waterproof cuticles on leaves + stem
how do sunken stomata reduce water loss
trap moist air -
reducing con gradient of water between leaf + air
- reduces amount of water diffusing
how do layers of hair on epidermis reduce water loss
to trap moist air around stomata
reducing con gradient of water between leaf + stomata reduces amount of water diffusing
how do curled leaves reduce water loss
protecting stomata from wind
reducing chance of diffusion + evaporation
how does a reduced no of stomata reduce water loss
fewer places for water to escape
how do waxy, waterproof cuticles reduce water loss
reduce evaporation
