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31 Cards in this Set
- Front
- Back
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3 factors affecting need for specialised exchange surface |
Size Sa: v ratio Level of activity |
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Which size organisms need specialised gas exchange surfaces |
Large multicellular organisms with small SA:V ratio |
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Why do large multicellular organisms need a specialised exchange surface |
They have several layers of cells. Diffusion is too slow to supply innermost cells because of long diffusion distance |
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Why dont small single celled organisms need a specialised exchange surface |
Cytoplasm close to external environment. Short diffusion distance Diffusion sufficient to supply cells with o2 and nutrients |
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3 features of a good exchange surface |
Large surface area Thin barriers Good blood supply
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Why does a specialised gas exchange surface need a rich blood supply [2] |
A rich blood supply can
provide sufficient gases quickly enough for all the metabolic reactions to take place [1] Waste gases can be removed from the organism quickly [1]
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Describe specialised gas exchange surface in plants [2] |
Large air spaces between spongy mesophyll cells [1] Gases enter the leaf through the stomata [1] |
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Function of smooth muscle in bronchus wall [2] |
Smooth muscles can contract, restricting the lumen of the bronchus [1] to prevent harmful gases from entering the lungs [1] |
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How are blood capillaries involved in gas exchange [3] |
Blood capillaries bring carbon dioxide to the alveoli [1] and take oxygen from the alveoli [1] This helps maintain a high concentration gradient of gases at the alveoli [1] |
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Process of gas exchange in alveoli [2] |
Co2 diffuses from blood in capillaries to alveoli [1] O2 diffuses from air in alveoli to blood in capillaries [1] |
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5 adaptations of alveoli for gas exchange |
1. Consist of squamous epithelial tissue/ elastic fibres. 2. LARGE SURFACE AREA. Increased by folding of walls. 3. GOOD BLOOD SUPPLY. Steep concentration gradient maintained so gas exchange continues 4. Alveoli/ capillary walls 1 CELL THICK reducing diffusion distance for gases 5. Lungs PRODUCE SURFACTANT. Thin layer of moisture lining alveoli to prevent it collapsing |
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Process of counter current flow to bring o2 into blood of bony fish [3] |
Blood moves in the secondary lamellae in opposite direction to water flowing over lamallae [1] Blood flowing under the water has a low concentration of oxygen and the water has a high concentration of oxygen [1] O2 diffuses into blood from water [1] |
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How do insects take o2 into their body [3] |
O2 from air diffuses into their body cavity via spiracles into thin tubes called trachea. [1] Trachea divides into tracheoles which it's ends are filled with tracheal fluid. [1] O2 diffuses from this fluid into insects body cells [1] |
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How to calculate breathing rate from a spirometer trace [1] |
Counting number of peaks in 1 minute |
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Describe 2 ways larger insects ventilate tracheal system by [2] |
Air sacs in tracheal system have flexible walls which can be squeezed by flight muscles to push air in and out [1] Movement of wings can alter thorax volume to ventilate tracheal system [1] Some insects e.g. locusts alter volume of their abdomen by specialised breathing movements [1] |
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Inspiration active process (needs ATP) |
1. External intercostal muscles contract. Internal ones relax 2. Ribs pulled up and out expanding ribcage 3. Diaphragm contracts and flattens 4. Thorax vol. Increases decreasing pressure in thorax 5. Atmospheric pressure is higher than pulmonary pressure 6. Air forced into lungs |
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Expiration process (needs less ATP doesn't use muscle contraction, ribcage falls) |
1. Internal internal coastal muscles contract 2. Ribs pulled inwards and diagram relaxes 3. Volume of thorax deceases increasing pressure 4. Pulmonary pressure is higher than atmospheric pressure 5. Air forced out of lungs |
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Adaptations of gills for efficient gas exchange [2] |
Many lamellae and secondary lamellae on main lamellea providing large surface area. [1] Short diffusion distance between water and blood [1] |
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Differences between tidal volume, vital capacity and residual vol. |
Tidal - vol. of air moved in and out of lungs with a normal breath Vital - max. vol. of air moved by lungs in 1 breath Residual- vol. Of air left in lungs after a forced expiration |
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Explain the function of epithelial cells in the airways of mammals in the defence against pathogens and suggest the importance of the cytoskeleton in carrying out this function. [4] |
goblet cells, secrete / release / make / produce / form, mucus
mucus traps, pathogens / microorganisms / bacteria cilia / ciliated cells / ciliated epithelium, sweep / brush / waft / move / AW, mucus cytoskeleton / microtubules / tubulin, move(s) / make(s) up, the cilia |
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A Student wants to examine tracheae of a grasshopper closely, with the use of a wet mount slide. A stain isn't needed. Using this information, describe how the student would prepare the slide. [3] |
Pipette a drop on water onto a slide [1] Use tweezers to place a section of the tracheae onto the drop of water [1] Stand a cover slip upright on the slide, then carefully tilt and lower it so it covers the specimen [1] |
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Explain how the grasshopper pumps air in and out of its body [2] |
It changes the volume of its body with rhythmic abdominal movements [1] This changes the pressure in its body so air is drawn in and out through the spiracles [1] |
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The grasshopper's gas exchange system contains fluid. Describe how the fluid is involved in gas exchange [2] |
Oxygen from air dissolves in the (tracheal) fluid, then diffuses from the fluid into body cells. [1] Carbon dioxide diffuses into the fluid in the opposite direction [1] |
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Explain one way in which the structure of the gill filament is adapted to its function [2] |
There are many gill plates/secondary lamallae which give a larger surface area [1] Increasing the rate of diffusion of gases [1] |
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Explain how changes in the buccal cavity of a bony fish allow the gills to be ventilated [4] |
When the fish opens its mouth, the floor of the buccal cavity is lowered, increasing the cavity's volume [1] This decreases the pressure in the buccal cavity, so water is drawn into it [1] When the fish closes its mouth, the floor of the buccal cavity is raised, decreasing the volume of the buccal cavity [1] This increases the pressure in the cavity so water is forced out across the gill filaments [1] |
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Why would a parallel-flow exchange system would be less efficient than a counter-current exchange system [3] |
In the parallel-flow system, the oxygen concentration gradient between the water and the blood decreases with distance along the gill plate [1] Rate of oxygen diffusion also decreases with distance along the gill plate [1] Less oxygen diffuses into blood than with a counter-current system, where the concentration gradient is maintained [1] |
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Chronic Bronchitis causes bronchi walls to become swollen and produce more mucus. Suggest why CB can result in shortness of breath [3] |
Less oxygen reachs the alveoli as the bronchi is swollen/filled with mucus [1] Concentration gradient of oxygen in alveoli is reduced [1] rate of which oxygen diffuses into the blood is reduced [1] |
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Emphysema is a lung disease which leads to breakdown of the alveoli walls. Suggest why a person with emphysema would have difficulty expelling air from their lungs [2] |
Loss of elastic fibres from alveoli [1] Harder for the lungs to recoil and expel air [1] |
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How is the concentration gradient of oxygen and carbon dioxide maintained between the alveoli and the blood [2] |
The alveoli are surrounded by a capillary network, so blood constantly takes oxygen away from the alveoli and brings carbon dioxide [1] The alveoli is ventilated, so the air in them is constantly being replaced, with oxygen being brought in and carbon dioxide being removed [1] |
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Why is it important to change the pressure inside the thorax during expiration [2] |
The pressure in the thorax increases during expiration above atmospheric pressure [1] This forces air out of the lungs as air moves from high pressure to low pressure [1] |
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Explain why not all of the air can be removed from the lungs [2] |
Some of the air remains in the bronchi/bronchioles/airways [1] Some air remains in the alveoli as they cant be completely flattened to the presence of the surfactant [1] |
