Gas Exchange Flashcards
Smaller organisms …
larger surface area to volume ratio
Larger organisms
smaller surface area to volume ratio
Single celled organisms
They have a large enough surface area to volume ratio to meet the gas exchange needs by simple diffusion across the cell membrane
Ficks law
surface area times concentration gradient divided by diffusion distance
What makes a good exchange surface?
Thin exchange surface
Large surface area
Large concentration gradient
To limit water loss insect may have
Exoskeleton skeleton which is a rigid outer shell skeleton covered with a waterproof cuticle
Relatively small surface narrative volume ratio to minimise area of which water is lost
Spiracles which open and close depending on levels of CO2
Movement of oxygen through the insect
Oxygen enters the insect through the spiracles and into the trachea
Spiracles close
Oxygen diffuses through the trachea into the trachea down a concentration gradient
Oxygen is delivered directly to respiring tissues
Features of an insect tracheal system
Spiracles. Gas enters and exits the insect tiny pores in the Exoskeleton skeleton they are open and closed to control the water lost by evaporation and open when CO2 levels increase.
Trachea = large network of tubes which provides a large surface area so faster rate of diffusion
Trachelous = they have thin walls so the diffusion distance is reduced .
They are highly branched so that is a large surface area.
Why diffusion happens in the gas exchange system of insects
O2
Tissues respire using oxygen which reduces the concentration of oxygen at the tissue
Oxygen moves from an area of higher concentration to an area of lower concentration souse from the trachea to the tissue
This lowers the oxygen concentration in the trachea so oxygen in from outside via the spiracles
Why diffusion happens in the gas exchange system of insects
CO2
Respiration produces CO2 increase in the concentration of the tissue
CO2 from an area of higher concentration to an area of lower concentration in the trachea
CO2 then move from a high concentration in the trachea to a low concentration outside via the spiracles
Fight or flight in insects
When an insect is at rest , water can build up in the trachelous
During flight, the insect buys an aerobically and produces lactic acid which dissolves in the water to produce lactate
This lowers the water potential of the muscle cell
As lactate builds up the water passes via osmosis from the trachealous into the muscle cells
This adaptation draws air into trachelous closer, therefore reducing diffusion distance
Gas exchange in fish
Knowledge
Each fish has four gills either side of its head
Gills have finger like projection called gill filaments
Each gill filament has gill lamellae
Lamellae contain capillaries which have then epithelium
Water moves into the mouth and over the gills
Lamellae is where most of the oxygen is removed
Explain ways in which the structure of the fish gills is adapted for efficient gas exchange
Many filament and Lamellae so there is a large surface area
Lamellae are thin so short diffusion distance
Counter flow of blood
Circulation replaces blood saturated with oxygen
Ventilation replaces water as oxygen removed
Counter current flow
Water and blood flowing opposite directions
Water has a higher concentration of oxygen than blood which maintains a concentration gradient
Across the whole length of the gill Lamellae
Adaptation of leaf for gas exchange
Flat= gives a large surface to volume ratio
Many stomata= Pores to allow air to move in and out of leaf
Air Spaces in leaf.= short distance between mesophyll cellsand air
Adaptations to reduce water loss
At night, the guard cells close to prevent water loss
Air spaces saturated with water vapour
Upper and lower cuticles have a waxy cuticle
Many stomata on lower surface
Describe how CO2 from outside reaches mesophyll cells
CO2 enters via stomata which are opened by guard cells
Diffuses through air spaces
Down diffusion gradient
Xerophyeric plants
Stomata in pits= reduced concentration gradient
Reduce number of Stomata = less surface area for water loss
Hairs to trap water vapour = reduced concentration gradient
Thick waxy cuticle = increased diffusion distance
Leaves reduced spines= less surface area for water loss
Rolled leaves = reduced concentration gradient
