Topic 3A- exchange and transport systems Flashcards
the bigger the organism the…
smaller the SA:V ratio
volume of a sphere
4/3XpiXr*3
how do substances get in and out of a single-cell
diffusion, over the small distance of a cell surface memebrane
meaning it is quick
reletivley large surface area compared to volume
how do multicellular organisms move substances
specialised exchange organs
e.g. lungs
what is mass transport
efficient systems to carry substaces to and fromtheir individual
in mammals, this is usually refered to the circulatory system
2 points- distance and surface area
why can multi-cellular organisms not use diffusion alone
1-cells deep within the body means that there is a big distance between them and the the outside environment
2-large animals have a low SA:V ratio, difficult for enough substances to be exhanged that will meet the large volume of a relitivley small surface area
mass transport in plants
transportation of water and solutes in the xylem and phloem
how does body size influence heat exchange
having a large volume means there is a big distance for the heat to travel
small organisms need a higher metabolic rate to generate enough heat
how does body shape influence heat exchange
a smaller surface area means less heat loss
foxes
adaptations for heat loss:
arctic fox-small ears and round fave reduce surface area
african fox- large ears and pointed nose maximising surface area
ficks law
what features increase the rate of diffusion
large surface area, short diffusion pathway and concerntration gradient
why is water needed in plants
- solvent-allow gases to dissolve
- hydrolysis reactions
- photosynthesis
- make the cell turgid(rigid)
pores on the epidermis layer of a plant
stomata
what controls the opening and closing of stomata
guard cells
why is the mesophyll layer surrounded by water
so the co2 can dissolve
why is the mesophyll layer known as ‘spongy’
space within it so co2 can diffuse much quicker to the cells
what does a vacuole do
pushes to organelle’s to the side meaning the chloroplasts are compacted to the side
meaning more of chance for light to it them for photosynthesis
where does photosynthesis take place
chloroplasts
why are plant cells in a pallisade shape
so they can all fit together, resulting in light being more likely to hit a chloroplast
opposite
equation for photosynthesis and respiration
carbon dioxide +water <> oxygen +glucose
why do stomata close at night
to keep moisture in, photosynthesis isnt happening due to no sunlight
what are the pores on insects called
spiricles
what are the advantages of insects having an exoskeloton
protection and prevnts water loss
what is an insects exoskeleton made from
chitin (B glucose) and a nitrogenous group
do insects have a large or small SA:V ratio
small
so cant rely on diffusion alone
what system do isnsects use
tracheal system
no lungs
order of events of the tracheal system
- spiricles
- trachea
- tracheoles
- tracheal fluid
- cell
what does the tracheal fluid do
dissolves the gas to be absorbed
what increases the rate of gas exchange in insects
anaerobic exersice
why do insects use anaerobic exersice
- this produces lactic acid within the cell which decreases the water potential in the cell
- meaning the tracheal fluid moves out of the tracheole into the cell
- allowing O2 to move quicker into the cell
why is it important that the pressure in the tracheoles is low
it allows a larger concerntration gradient from the atmosphere meaning more oxygen is drawn in
tracheal fluid
when the insect isnt active…
the fluid seeps from the surrounding cells into the tracheoles
when an insect is active…
muscles will draw up the fluid (had dissolved oxygen in it)
for respiration
what increases when the tracheal fuid is drawn up when the insect is active
surface area, allowing O2 to diffuse directly through the tracheal walls
how do larger insects ventilate the tracheal system
- air sacs- can be squeezed by flight muscles to push air of the the trachae
- alteration of the thorax when flying- movement/ expansion of thorax cavity helps draw air in
front and back spiricles
what is the specialised breathing mechanism of larger insects
- expand abdomin which close spiricles at the back of the absomin and opens the front ones
- abdomin contacts again and the spiricles at the back open allowing CO2 to exit whilst the ones at te front close
what do rings of chitin on the trachea do
adds structure, prevents them from collapsing when the muscle contracts for mass transport
what is a xerophyte
plants adapted to low water areas
what do curved leaves do
they protect the stomata from the wind and so moist air can be trapped on the inside
e,g, marram grass
sunken stomata
trap moist air surrounding the stomata meaning the concerntration gradient is reduced to prevent evapourisation
reduced no. of stomata
fewer spaces for water to escape
thick waxy cuticle
reduces evapourisation
layer of hairs surrounding the stomata
further trap most air surrounding the stomata
roots
cacti
- deep roots to find further water from lower levels of water
- shallow roots which means they can get the water from flash floods quickly
what are succulents
plants that ca stare water within their stem
spines
- reduced SA:V ratio-so less water loss
- can produce some shade as protection from the sun, ruducing transpitration
on cacti where is the stomata found
which means …
on the stem, meaning that is where photosynthesis takes place
is water concerntration lower in water or air
water
where does gas exchange happen on a fish
gills
what is the structure of a gill filament
flatened plates
what are the filaments of a gill attached to
gill arch
what are on the gill fillaments and why
lamellae- they increase surface area so more oxygen is diffused
what do gill rakers do
prevent debris from enetering the fish from the gills
what is the operculum
and what does it do
covering over the gills for protection and to make the fish more streamline
e.g. this helps with salmon when swimming up stream to reproduce
how does oxygen reach the gills
passes through the mouth and filters through the gills
how many layers of gill filamets are there
2
why wont gills work on land
in thw water it spreads out the lamellae, out of the water they will stick together which decreases the surface area forgas exchange
how do fish retain oxygen
counter-current system
in the name!
what is the counter-current system
the capillary networkof blood flowing in the opposite direction to the water menaing there is always a diffusion gradientbetween the water and the blood
so oxygen can diffuse into the blood
equilibrium is never met
