Gas Exchange

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  • Created by: lridgeway
  • Created on: 06-05-18 15:49
What must all exchange surfaces be/have?
large surface are to volume ratio, thin so there is a short diffusion pathway, moist to ensure diffusion occurs and be able to maintain a concentraion gradient
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Why are single celled organisms good at gas exchange?
they have a large surface area to volume ratio and a thin cell membrane so gain enough oxygen and lose enough carbon dioxide through the membrane
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Name a multicelluar organism that does require a ventilation system and explain why?
worm as they have a long cylinderical shape so have short diffusion pathways, has moist skin and have a low oxygen requirement as they done move much. They also have a large surface to volume ratio
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Describe reptilian gas exchange surfaces
more complex lungs than amphibians and increased surface area for gas exchange
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Describe amphibians gas exchange surfaces
moist skin with well developed capillary network below so gas exchange can happen through the skin. They also have small simple lungs that are used when they are active.
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How are amphibian lungd ventilated?
They are ventilated by a buccal pump using nose and buccal cavity. The glottis prevents air backflow
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Describe birds gas exchange surfaces
similar internal structure to mammals but more efficient ventilation as they have air sacs that act as bellows. these mean unidirectional flow and that the lungs are always filled with fresh air.
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How is unidirectional flow achieved in birds?
air goes from one set of air sacs over the lungs to the other set of air sacs
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Where are spiracle on insects and hwat type of gas exchange system do they have?
thorax and abdomen and a tracheal system
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What are the tubes in the traheal system called and what is their function?
longer ones - trachea which are held by chitin so no gas exchange occurs. smaller ones - tracheoles which pentrate cells and have no chitin so gas exchange can occur.
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How is oxygen supplied to cells in insects?
it is directly to cells through the tracheal system and no blood is used fro transport of gases
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Explain how some insects use spiracles for ventilation
they have rythmic flattening and expanding of the thorax so air flows in some spiracles and out others
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What is at the tips of tracheoles and how does it achieve its function?
watery fluid and during activity muscles release latic acid this lowers water potential of cells so water moves by osmosis from tracheole to cell which increases SA so more oxygen can diffuse and there is smaller diffusion distance
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What so spiracles do to maintain water?
they close in hot dry conditions and hairs around them also trap water
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Name the main features of fish's buccal cavity
pharynx, operculum, opercular cavity, opercular opening, oesophagus, gills
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Name the main features of a gill
gill rackers, gill arch, gill filament/lamella, gill plates
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What is the gill arch function?
to support the gill filaments
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How many gill filament are on one bone arch?
two which unless kept apart by water stick togther. They increase the surfcae area.
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What are the gill plates function and where are they found?
further increase surfcae are and are found on gill filament. blood flows across them from inner side to outer side
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What are the steps for fish inspiration?
volume of buccal cavity increases as pharynx lowers, buccal cavity expands, operculum bulge outwards to create low pressure, water moves over gills
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What are the steps for fish expiration?
buccal cavity contracts as pharynx raised which creates high pressure, this forces water through gill slits, opercular cavity contracts creating high pressure, the opercular valve opens and water is expelled, mouth is closed
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Explain couter current flow in terms of gills
blood in gill plates flows in opposite direction to the water which ensures there is always a concentration gradient
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What happens in parallel current flow?
both start at 100% so an equilibrium is reahced at 50%
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What does having counter current flow ensure?
that there is transfer of oxygen along the entire gill plate and that as much oxgen is transferred from water to blood a possible making more efficient gas exchange
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How does a leaf's shape assist its gas exchange?
large surface area, thin so short diffusion pathway and they are held away from rest of pant to keep airflow and maintain a concentration gradient
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What is a stomata?
hole in bottom of palnt to allow gas exchange
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How does a stomata work (basic)?
guard cells inner cell wall thicker and less elastic so when water moves in by osmosis cells expand irregularly (when they are turgid) , opening stomata (they do this in rhythm, open day closed night)
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What is the potassium movement hypothesis?
K+ ions active transport into cell, photosynthesis increases and CO2 level lowers. CO2 highers pH which is optimum conditions for enzyme to turn starch to malate. these ions accumulate in the cell lowering water potential. water moves in by osmosis
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What is the potassium movement hypothesis over ridden by?
growth substance ABA which is produced when a plant suffers water stress
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Describe the traditional starch-sugar hypothesis?
increase in sugar in guard cells during the day, fall in water potential, water enters cell by osmosis and become turgid so open
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What are the problems which the starch-sugar hypothesis?
no evidence of sugar build up. response of stomata too quick to be sugar accumulation, in some plants stomata open before day break
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What is the function of the waxy cuticle?
waterproof layer that prevents water loss by evaporation
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What is the fucntion of the epidermis?
transparent layer to allow light and offers protection to the leaf
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What is the function of the palisade mesophyll layer?
photosynthesis so cells are deep and long with many chloroplasts
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What is the function of the spongy mesophyll layer?
exchange surface from air spaces, water evaporated too
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What is the function of air spaces?
for diffusion to occur into cells
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What is the function of the vascular bundle?
xylem vessel transports water (95% lost through stomata, 5% used for photosynthesis and to make cells turgid), phloem transports sugars etc
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What is the function of guard cells
control the opening and closing of the stomata
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How do humans breath in? (part 1)
external intercostal muscles contract to increase ribcage volume. diaphragm mucscle contracts and flattens. outer pleural membrane moves out. reduces pleural cavity pressure. pulls inner pleural membrane and it moves outwards.
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How do humans breath in? (part 2)
pulls on lung surface causing alveoli to expand, volume of thorax increases, pressure falls below atmospheric pressure so air is forced into the lungs and over the lung surface. lungs inflate
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How do humans breath out? (part 1)
intercostal muscles contract to decrease ribcage volume. diaphragm relaxes and arches. outer pleural membrane moves inwards. pleural membrane pressure increases. inner pleural membrane moves inwards. pushes on lung surface causing alveoli to shrink.
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How do humans breath out? (part 2)
alveolar pressure increases to above atmospheric pressure and air is removed
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Which of these is an active process and which is a passive process?
breathing in is active due to muscle contraction, breathing out is passive due to muscle relaxation
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What is the respiratory surface in humans and what happens there?
alveoli. oxygen diffuses across membrane into the blood and carbon dioxide diffuses across membrane from the blood to the alveoli
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What is the adaptations of the alveoli?
large surface area due to bubble/cloud shape, moist to ensure diffusion can occur, one cell thick for short diffusion pathway, well supplied with blood as it is surrounded by many capillaries
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What happens during exercise?
external intercostal muscles contract and pull ribcage further for deeper breath in. internal intercostal muscles and pull ribcage in more powerfully for deeper breath out. this can be improved by training
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Name the parts of the respiratory system
trachea, epiglottis, bronchi (bronchus), bronchioles, diaphragm, alveoli, intercostal muscles, pleural membrane, pleural cavity
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Other cards in this set

Card 2

Front

Why are single celled organisms good at gas exchange?

Back

they have a large surface area to volume ratio and a thin cell membrane so gain enough oxygen and lose enough carbon dioxide through the membrane

Card 3

Front

Name a multicelluar organism that does require a ventilation system and explain why?

Back

Preview of the front of card 3

Card 4

Front

Describe reptilian gas exchange surfaces

Back

Preview of the front of card 4

Card 5

Front

Describe amphibians gas exchange surfaces

Back

Preview of the front of card 5
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