2.2 - adaptations for gas exchange Flashcards
what are the adaptations of living organisms for gaseous exchange?
- thin (short diffusion pathway)
- permeable
- moist
- large surface area
- constant supply of blood
why do amoeba have a large surface area to volume ratio?
because its large surface area allows for oxygen to quickly diffuse throughout the organism to cater for its oxygen requirements,
how are large multi-cellular organisms adapted for oxygen uptake?
specialised respiratory pigment surfaces,
circulatory systems,
blood pigments.
how are amoeba specialised for gas exchange?
single cells give large surface area to volume ratio, therefore oxygen quickly diffuses through and it enough to supply its oxygen for respiration
how are flatworms specialised for gas exchange?
- flat worms are flat, giving it a larger surface area to volume ratio, no part of its body is far from surface hence short diffusion distance
what do bony fish have that is a specialised gas exchange surface?
the gills - gill lamellae where water gets pushed over
how are earthworms specialised for gas exchange?
- has a smaller SA:V than a flatworm
- skin is respiratory surface, kept moist by secreting mucusm (oxygen dissolves before diffusing into)
- low oxygen requirement (slow moving)
- has haemoglobin, so carries oxygen around body to maintain concentration grad at skin to keep oxygen flowing in and carbon dioxide out
what is the ventilation system in bony fish?
3 stages to it, pressure changes in the buccal cavity allows water to be passed continuously over the gills
what are the first stage of ventlation system of bony fish?
- mouth opens and floor of buccal cavity is lowered, volume increases,e e and pressure decreased
- therefore, water is pulled into the buccal cavity from the outside
what is the second of the ventiation system in bony fish?
the mouth closes, and the buccal cavity contracts (raising the floor) water keeps getting forced across the gills
what is the third stage of the ventilation system of bony fish?
pressure in the gills cavity increases and forces the operculum open (water leaves)
what do gills contain?
gill lamallae, gill arch, gill rakers
what water flow do the gills have?
counter-current flow
what does counter-current flow mean?
water flows between the gill plates, opposite direction to the blow flow in the gill capillaries
why is counter-current flow effiecient?
it increases the efficiency of diffusion by maintaining a steep concentration gradient across the gill plate
describe what a countercurrent flow graph looks like compared to a parallel flow diagram?
counter-current flow - diagonal going from bottom left to top right, equal distance
equilibrium not reached
parallel flow - , equilibrium is reached halfway - starts very high distance between but meets halfway (>–)
what type of fish has a parallel flow?
cartilaginous fish/sharks
what are the 5 differences between counter-current flow and parallel flow?
OCEDO
c-current - water flows through gill plates in the opposite direction to blood flow in capillaries
parallel - water flows through gill plates in same direction as blood flow in the capillaries
c-current - steep concentration gradient is maintained
parallel - the concentration gradient is not maintained as equilibrium is reached
c-current - diffusion of oxygen from water is across the ENTIRE gill plate
parallel - diffusion of oxygen from water does not occur across entire gill plate
c-current - high rate of diffusion
parallel - lower rate of diffusion as equilibrium reached
c-current - more oxygen is absorbed into the blood
parallel - less oxygen abrobed into the blood
Opposite
Conc grad
Entire
Diffusion
Oxygen
what do amphibians, reptiles and birds share for gas exchange?
- large SA
- moist
- thin walls
- blood pigments in the circulatory system (haemoglobin)
- internal lungs (minimise water loss)
- ventilation mechanism (air in and co2 out)
what do amphibians use for gas exchange?
active - uses lungs
inactive - moist skin
what do reptiles use for gas exchange?
efficient lungs - highly folded for more SA
(impermeable skin)
what do birds use for gas exchange?
small and compact lungs, lots of blood capillaries for gas exchange - helped by the movement of the wings to ventilate
what is the impermeable outer skin on an insect?
its exoskeleton covered by an impermable cuticle (made of chitin)
what are the holes in an insects exoskeleton?
spiracles
what do the spiracles in an insect lead to?
tracheae, these are branched and lined with chitin
how do insects reduce water loss?
opening and closing the spiracles, lined with a muscular
where does the gas exchange occur in insects?
tracheoles - at the end of them, oxygen passes directly into the cells
what are the parts of an insects body?
head, thorax, abdomen
how is the tracheal system ventilated?
compression and expansion of the abdomen (e.g air goes into the thorax spiracles and out of the abdomen spiracles as it gets compressed)
how does oxygen rapidly diffuse into the muscles of insects?
the tracheoles are very short, short diffusion pathway
how do insects optimise thie oxygen intake during activity?
tracheal fluid levels decrease, which draws more oxygen into the tracheal
what are the components of the human repsiratory system?
- inner pleural membrane (attached to surface of lungs)
- outer pleural membrane (attached to intercoastal muscles)
- plueral cavity (between the plaural mems)
- larynx (above bronchus)
- bronchioles
- bronchi
- ribs
- chest cavity
- diaphragm
- intercostal muscles
- thorax
desribe the process of inspiration? (negative pressure breathing)
- external intercostal
muscles contract they raise the ribcage - diaphragm flattens
- the outer pleural membrane is pulled out
- reduces pressure in the pleural cavity and the
inner pleural membrane moves outward - this pulls on the surface of the lungs and causes
the alveoli to expand
-volume of thorax increases and pressure decreases - alveolar pressure decreases to below atmospheric pressure and air is drawn into the lungs.
describe the process of expiration?
- external intercostal
muscles relax they move ribs in and down - diaphragm relaxes and curves up
- the outer pleural membrane is pulled in
- increasing pressure in the pleural cavity and the
inner pleural membrane moves back inward - this pulls on the surface of the lungs and causes
the alveoli to reduced in volume
-the volume of thorax decreases and pressure increases so air is forced out
where does gas exchange occur in mammals?
alveoli
how are the alveoli specialised for gas exchange?
- large surface area
- moist walls for gases to dissolve
- thin walls - short diffusion pathway
- large capillary network (constant blood supply)
- steep concentration gradient as blood is carried away once oxygenated
what are the four components of the alveoli?
alveoli
blood capillaries
pulmonary artery
pulmonary vein
what covers the surface of the alveoli to prevent collapse?
- a surfactent - reduces surface tension when breathing out so they dont collapse
what is the oxygen percentage in the inspired air, alevolar air and expired air?
inspired - 21%
alveolar - 14%
expired - 16%
lower alveloar to draw it in
what is the co2 percentage in the inspired air, alevolar air and expired air?
inspired - 0.04
alveolar - 5%
expired - 4%
co2 is from the respiration, diffused from plasma into alveoli
how do you calculate oxygen absorption?
%oxyen extracted =
%oxygen absorbed
divded by
%of air that is oxygen
what are the components of a leaf (angiosperm)?
in descending order:
- waxy cuticle
- upper epidermis
- palisade mesophyll
- spongy mesophyll
- vascuclar bundle (xylem, phloem, bundle sheath parenchyma)
- air spaces
- lower epidermis
- guard cells
- stomata
what is the function of the waxy cuticle?
- reduces water loss from leaf surface by evaporation
what is the function of the upper epidermis?
- transparent cell which allows light in from photosynthesis
- secretes the waxy cuticle
what is the function of the palisade mesophyll?
- contains chloroplasts for photosynthesis (primary place of photosynthesis)
what is the function of the spongy mesophyll/air spaces?
- also contains chloroplasts for photosynthesis
- air spaces are for gas exchang/circulation
what is the function of the vascular bundle (xylem and phloem)?
-xylem for the transport of water and minerals
- phloem for the transport of salts and products of photosynthesis
what is the function of the guard cells?
these become flaccid and turgid depending on water potential
what is the function of the stomata?
- this allow for gaseous exchange
what are the adaptations of the leaf for gaseous exchange?
MACS CD
- spongy mesophyll tissue allows for the circulation of gases
- air spaces permeate plant tissues
- stomata allow gases to enter and leave
- gases diffuse through the stomata down a conc grad
- gases then can diffuse inbetween the mesophyll cells
- gases can dissolve in the moist layer on each cell
Moist
Air spaces
Circulation
Spongy mesophyll
Conc grand
Diffusion into
what are the adaptations of the leaf for photosynthesis?
COST DC
- leaves have a large surface area
- leaves orientate themselves to expose themselves to as much sun as possible
- leaves are thin, allows light to penetrate lower levels
- cuticle and epidermis are transparent - lets light in
- palisade mesophyll anre densely arranged
- palisade cells are packed with chloroplasts for the most photosynthesis
Thin
Orientation
Surface Area
Transparent
Densely packed
Chloroplasts
how do chloroplast optimise the amount of light absorption?
they can move around the cell to get the best position
what structure do the guard cells have?
- shaped like two sausages (have chloroplasts)
- thick inner wall - allows to swell and close the stomata
- thin outer wall
where are the stomata found on the leaf? what do threy do at night?
mostly on the lower under side as in shade to reduce water loss
they close at night to prevent water loss
what is the malate theory during the opening of the stomata?
AM W TS
- in light chloroplasts in the guard cells produce ATP through photosynthesis
- ATP is used for active transport of K+ into the guard cells.
- therefore the stored starch is converted into malate
- K+ and malate ions lower water potential to below
that of surrounding cells, so water moves in by osmosis. - the guard cells become turgid, and the thinner outer wall curve outwards
- this opens the stomata allowing for gas exchange
ATP - active trans
M - malate converted
W - increases water potential of cell
T - guard cell becomes turgid
S - stomata opens
what is the malate theory of the closing of the stomata?
- too little light intensity means no photosynthesis so the K+ ions diffuse down the conc grad and out of the guard cells
- malate is converted back into starch (condensation)
- this increases the water potential of the guard cells
- water leaves the guard cell by osmosis
- the guard cell becomes flaccid, closing the stomatal pore and prevemting gas exchange and water loss
