Gas Exchange Flashcards
Which materials may need to be interchanged between an organism and its environment for exchange?
-respiratory gases
-nutrients
-excretory products
-heat
What are the waste products of metabolism?
-carbon dioxidr
-ammonium
-urea
What happens to SA:V ratio as an organism gets bigger?
-decreases
What happens to SA:V as an organism gets smaller?
Increases
Calculate the SA and Vol of an organism if their lengths are from 1 to 6
How do u calculate the surface area of a cube?
Length x Height x 6 sides
How do you calculate the volume of a cube?
Length x Width x Height
How do u calculate SA:Vol
SA / vol
What is required to produce ATP during aerobic respiration?
Oxygen
What is the waste product in aerobic respiration?
Carbon dioxide
What do all organisms rely on diffusion for?
-the exchange of oxygen and carbon dioxide down their concentration gradient
Give some examples of single celled organisms
-protists and prokaryotes
What do single celled organisms have?
-a large enough surface area to volume ratio to meet their gas exchange needs by diffusion across their cell membrane
What do larger organisms such as humans have?
-a relatively small surface area to volume ratio so they can’t rely on diffusion alone to meet the oxygen demands of all their cells
What have larger organisms developed to help them meet oxygen demands to all of their cells?
-specialised gas exchange surfaces and systems which have adaptations to ensure rapid diffusion of gases
What happens to an organism as surface area to volume ratio increases and what happens ti them in terms of heat?
-SA:vol decreases as an organism gets larger
-larger organisms loose heat more slowly across its surface than a smaller organism
What is Ficks Law?
What makes a good exchange surface?
-large surface area
-large concentration gradient
-thin exchange surface (few membrane or thin walls)
What is the most effective surface for gas exchange?
-large, thin and permeable area
What must insects balance?
-water loss and gas exchange surface
What may insects have/be to limit water loss?
-waterproof covering over their body surfaces
-relatively small SA: Vol
-impermeable to gases
-use tracheal system
-need to avoid dehydration
Describe the waterproof covering that insects have to help minimise water loss
-usually a rigid outer skeleton (exoskeleton) covered in a waterproof cuticle
Why may insects having a relatively small SA:VOL ratio help in gas exchange?
-minimise the area over which water is lost
Describe the movement of oxygen through the insect (4 marks - NEED TO KNOW)
- Oxygen enters the insect through spiracles and into the trachea
- Spiracles close
- Oxygen diffuses through the trachea into the tracheoles down a concentration gradient
- Oxygen is delivered directly to the respiring tissue
How is carbon dioxide produced and what is it produced by?
-by aerobically respiring tissues
-tissues move in the opposite direction and exit the insect when apiracles open
Describe the tracheoles within an insect
-small tubes with thin walls so diffusion distance is reduces which extend throughout the body tissues
-highly branched so there is a large surface area
Describe the trachea in an insect and how it links to Ficks law
-network of tubes supported by strengthened rings
-provides tubes full of air so that diffusion is fast
Describe spiracles in an insect and what they do in terms of gas exchange
-gas enters and exits the insect through these tiny pores
-they are opened and closed to control water loss by evaporation
-open when co2 levels increase
Explain why oxygen diffusion happens in the gas exchange systems (tracheal system) of an insect
-tissues respire using oxygen which reduces the concentration of oxygen at the tissue
-oxygen moves from an area of higher concentration to lower concentration so moves from the trachea to the tissue
-this lowers the oxygen concentration in the trachea so the oxygen moves into the trachea denim outside the insect via the spiracles
Why does carbon dioxide diffusion happen in the gas exchange systems (tracheal system) of insects?
-respiration produces CO2 increasing the concentration at the tissue
-CO2 moves from an area of high concentration at the tissue to the low concentration in the trachea
-CO2 then moves from high concentration in trachea to low concentration outside the insect via spiracles
Explain ventilation (abdominal pumping) in insects
-movement of the insects muscles create a mass movement of air in and out or the trachea which increases the rate of gaseous exchange
-also have small air sacs in their trachea
-muscles around their trachea contract and pumps the air sacs deeper into their tracheoles
Describe how an insect may get additional oxygen during flight
-when an insect is at rest, water can build up in their tracheoles
-during flight, the insect may partly respire anaerobically and produce some lactate (lactic acid)
-lowers the water potential of the muscle cells so as lactate builds up, water passes via osmosis from the tracheoles into the muscle cells
-this adaptation draws air into the tracheoles closer to the muscle cells and therefore reduces the infusion distance for oxygen when it’s most needed
Explain 3 ways in which an insects tracheal system is adapted for efficient gas exchange (3 marks- must include Ficks law)
- Many tracheoles are highly branched so large surface area
- Concentration gradient is maintained through spiracles opening and closing
- Thin exchange surface so that the diffusion distance is reduced (tracheoles shave small tubes with thin walls)
What is the gas exchange organ in a fish?
Gills
What property of Ficks law do fish gills have?
-large surface area
How many gills does each fish have and where are they?
4 on the side of its head
Where does water move into a fish?
Mouth
Where does water leave the fish?
Through/over the gills
What do gills have?
Gill filaments
What can gill filaments be described as?
Finger like projections
What does each gill filament have?
Lamallea
What do lamallea do?
Increase the surface area (as they are at 90 degrees)
What does each lamallea have?
Its own blood capillary
What do gills allow in terms of O2 and CO2?
-allow o2 to be absorbed from water and co2 to be excreted from the blood
How does oxygen reach gill filaments?
-water carrying oxygen enters through the fish mouth, passes through the lamellae on the gill filaments where most of the oxygen is removed
-then water containing little oxygen leaves through the gill opening
Describe lamellae
-each gill filaments where most has gill lamellae
-gill lamellae are positioned at right angles to filaments
-lamellae contains capillaries
-thin epithelium (for short distance between water and blood)
(Each has a very thin membrane in close proximity to a blood capillary)
Explain two ways in which the structure of fish gills is adapted for efficient gas exchange (2)
-many filaments/lamellae so there is a large surface area
-lamellae are thin for a shirt diffusion pathway
How is a concentration gradient maintained in a fish?
Through ventilation
Describe countercurrent flow
-the position of the filament and lamellae means that water and blood flow in opposite directions
-this massively increases the fish’s ability to absorb oxygen from the water as a diffusion gradient is always maintained
What must you always state in a question about countercurrent flow?
-water and blood flow in opposite directions
-this maintains a concentration gradient across the whole length of the lamellae
Draw a diagram of the structure of the gills
Draw a diagram of the structure of a leaf
How are leaves adapted for gas exchange?
- Flat- larger surface area to volume ratio
- Many stomata- pores to allow air to move in and out of leaf
- Air spaces in leaf so short distance between mesophyll cells and air
Describe how CO2 is diffused for photosynthesis
-mesophyll cells photosynthesise and this reduces the concentration of CO2 in cells
-CO2 diffuses from the air spaces into the cells
-this in turn reduces the CO2 concentration in the air spaces causing CO2 to move into the air spaces from the air outside the lead, through the stomata
Describe how O2 is diffused
-mesophyll cells produce O2 as a result of photosynthesis
-O2 diffuses into the air spaces from the cells
-this increases the concentration of O2 in the air spaces, causing O2 to move from the air spaces to outside the lead via the stomata
What adaptations do plants have to reduce water loss?
-at night, guard cells close the stomata to prevent water loss
-less CO2 is required at night due to the lack of available sunlight for photosynthesis
-upper and lower surfaces have a waxy cuticle
-most stomata are found/ distributed on the lower surfaces
Describe how carbon dioxide in the air outside a lead reaches the mesophyll cells inside the leaf (4)
- (Carbon dioxide enters) via stomata
- (Stomata opened by) guard cells
- Diffuses through the air spaces
- Down diffusion gradient
What are xerophytic plants?
Plants that live in dry/arid environments
Describe the adaptations that xerophytic plants have to reduce water loss and link each to Ficks law
- Reduces number of stomata = less SA for water loss
- Stomata in pits= reduces concentration gradient
- Hairs to trap water vapour = reduces concentration gradient
- Rolled leaves = reduced concentration gradient
- Leaves reduces to spines= less SA for water loss
- Thick waxy cuticles= increased diffusion distance
