gas exchange Flashcards
(16 cards)
the process of getting additional oxygen during flight
insect at rest = water builds up in tracheoles
during flight = anaerobic respiration, lactate produced, lowers water potential in muscle cells, lactate builds up, water moved by osmosis into muscle cells from tracheoles, air drawn into tracheoles closer to muscle cells - reducing diffusion distance
how do insects limit their water loss
- waterproof covering = exoskeleton covered in waterproof cuticle
- small SA:vol ratio = minimise area which water is lost
what is abdominal pumping in insects
muscle movement created mass movement of air in and out of the trachea = inc rate of gaseous exchange
muscles around trachea contract and pump air into small air sacs deeper into tracheoles
features of parts of the tracheal system
- spiracles = gas enters and exists insect, close + open to control water loss by evaporation, open when high CO2 levels
- trachea = network of tubes, supported by strengthened rings, provides tubes full of air for fast diffusion
- tracheoles = small tubes with thin walls for a short diffusion distance, highly branched provide large SA
describe the movement of oxygen through insect (4)
- oxygen enters through spiracles and into the trachea
- spiracles close
- oxygen diffuses through tracheae into tracheoles
- oxygen delivered directly to respiring tissues
why does diffusion happen in the tracheal system in insects
oxygen
1. tissues respire using O2, reduces oxygen concentration at the tissue
2.oxygen move from a higher concentration to a lower concentration (tracheae to the tissue)
3. lower oxygen concentration in tracheae, oxygen moves into tracheae from outside the insect via spiracles
carbon dioxide
1. respiration produces CO2, increases CO2 concentration at the tissue
2. CO2 moves from a higher concentration (tissue) to a lower concentration (tracheae)
3. CO2 moved from a higher concentration (tracheae) to a lower concentration (outside the insect) via spiracles
2 adaptations of the structure of fish gills for gas exchange
- many lamellae = large SA
- thin epithelium = short diffusion distance
countercurrent flow mechanism
- blood and water flow in opposite directions
- maintaining a concentration gradient
- across the whole length of the gill lamellae
- blood always passes water that has high concentration of oxygen
what is the most efficient type of blood flow in fish for oxygen absorption
countercurrent flow:
- no equilibrium is reached
- concentration gradient is maintained across the whole length of the lamellae
- almost all oxygen from the water diffuses into the blood
exam q =
explain how gills of a fish are adapted for efficient gas exchange (6m)
- many lamellae = large SA
- thin epithelium = short diffusion distance
- water and blood flow in opposite directions so a concentration gradient across lamellae is maintained
- water is always next to blood with a lower oxygen concentration
- circulation replaces blood saturated with oxygen
- ventilation replaces water with low oxygen concentation
what are the leaf adaptations for gaseous exchange
- flat = larger SA : volume ratio
- many stomata = allows air to move in and out of leaf
- air spaces in the leaf = short distance between mesophyll cells and the air
adaptations of the leaf to reduce water loss
- guard cells close stomata at night = prevent water loss
- waxy cuticle on upper and lower surface = waterproof, prevents water loss by evaporation
- most stomata on lower surface
- air spaces are saturated with water vapour from xylem
why is there a diffusion of O2 in plants
- mesophyll cells produce oxygen from photosynthesis
- oxygen diffuses into air spaces from cells
- higher concentration in air spaces causing oxygen from air spaces to move outside the leaf via spiracles
- along the concentration gradient
adaptations of xerophytic plants
- thick waxy cuticle = increases diffusion distance (prevents water loss by uncontrolled evaporation)
-small leaf SA= less surface area for evaporation - low number of stomata = less surface area for evaporation
- sunken stomata = reduces concentration gradient
(maintains humid air around the stomata) - rolled leaves = reduces concentration gradient
(maintains humid air around the stomata) - hairs to trap water vapour= reduces concentration gradient
why is there diffusion on CO2 in plants
- mesophyll cells photosynthesise, reducing the concentration of CO2 in cells
- CO2 diffuses from air spaces into cells
- reduces CO2 concentration in air spaces causing CO2 to move into air spaces from outside of the leaf via the stomata
-along the concentration gradient
exam q=
describe how CO2 in the air outside of a leaf reaches mesophyll cells inside the leaf
- CO2 enters via stomata
- stomata are opened by guard cells
- CO2 diffuses through air spaces
- down the diffusion gradient
