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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011 watch

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    Can someone please explain ventilation in insects please?
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    (Original post by DoaaK)
    what are the coronary arteries? D:
    no idea!
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    I think I'll be tackling the 6 mark question first
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    (Original post by parallal)
    Can someone please explain ventilation in insects please?
    Movements in the muscles of the insects cause mass movements of air into/out of the trachea. Gas enters and leaves trachea through pores called spiracles. When spiracles open water can evaporate from the insect. For efficient diffusion, the diffusion pathway must be kept short, therefore limiting the size of insects.
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    (Original post by Kandy_Kain_94)
    I think I'll be tackling the 6 mark question first
    Same... unless its tissue fluid LOL
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    It's sickening to hear all these model answers
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    (Original post by parallal)
    Can someone please explain ventilation in insects please?
    Ventilation helps to cause mass movements of air in and out of the trachea. This is achieved by the contraction of muscles.
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    (Original post by ksimmi25)
    Thank you I think I kind of get it, better than I did before but what would be the third replication? I know there would be 8 possibilities? - How do you work them out?
    sorry it's not really clear.
    So originally it's ii,
    then this become Ii iI (during sc replication, the strands separate and become I, i, i and I which are joined by free nucleotides all 15N)
    becoming : II, Ii, iI, II
    this then becomes
    II, II, II, Ii, iI, II, II II
    8 results!

    Sorry late reply, was revising som philosophy and ethics too
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    (Original post by Jorgeyy)
    Same... unless its tissue fluid LOL
    I hope its tissue fluid lol...It's not about gas exchange in fish/insects
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    Is this all we need to know about fish?

    - The pharynx is lowered, and pressure decreases inside the fish's mouth, so water is drawn in.
    - The pharynx then closes and pressure is high in the mouth, so water is forced out past the gills over the operculum.
    - Gills have many filaments and lamallae to increase surface area for efficient gas exchange.
    - The counter current system improves gas exchanges because blood travels in the opposite direction of water. This means that blood always has a lower oxygen concentration than the water, so the oxygen will diffuse into the blood.

    Can anyone add to that or is that all we need to know?
    Thanks
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    (Original post by Kandy_Kain_94)
    I hope its tissue fluid lol...It's not about gas exchange in fish/insects
    Pm me a model answer regarding tissue fluid? It's the one thing I think I would struggle with if it came up for 6 marker ! <3
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    (Original post by Jorgeyy)
    Pm me a model answer regarding tissue fluid? It's the one thing I think I would struggle with if it came up for 6 marker ! <3

    me too please ! I hate tissue fluid.
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    (Original post by Nugard123)
    Is this all we need to know about fish?

    - The pharynx is lowered, and pressure decreases inside the fish's mouth, so water is drawn in.
    - The pharynx then closes and pressure is high in the mouth, so water is forced out past the gills over the operculum.
    - Gills have many filaments and lamallae to increase surface area for efficient gas exchange.
    - The counter current system improves gas exchanges because blood travels in the opposite direction of water. This means that blood always has a lower oxygen concentration than the water, so the oxygen will diffuse into the blood.

    Can anyone add to that or is that all we need to know?
    Thanks
    Yes that's pretty much it. Although you may want to add during inspiration when the mouth opens the pharynx is lowered due to muscle contractions and this also increases the volume of the chamber. But aside from that it looks fine
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    (Original post by Nugard123)
    Is this all we need to know about fish?

    - The pharynx is lowered, and pressure decreases inside the fish's mouth, so water is drawn in.
    - The pharynx then closes and pressure is high in the mouth, so water is forced out past the gills over the operculum.
    - Gills have many filaments and lamallae to increase surface area for efficient gas exchange.
    - The counter current system improves gas exchanges because blood travels in the opposite direction of water. This means that blood always has a lower oxygen concentration than the water, so the oxygen will diffuse into the blood.

    Can anyone add to that or is that all we need to know?
    Thanks
    Looks pretty good to me, I probably wouldn't even mention the pharynx myself just that water is drawn in and forced out over the gills ^^
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    Is the cohesion, in cohesion tension theory, caused by hydrogen bonds or Van der Waals'?
    cos the text book says hydrogen, but i'm sure my teacher told us it was Van der Waals' :/

    and could someone try explain root pressure to me?

    thanks!
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    (Original post by ScienceGeek3)
    Yes that's pretty much it. Although you may want to add during inspiration when the mouth opens the pharynx is lowered due to muscle contractions and this also increases the volume of the chamber. But aside from that it looks fine
    Ok thanks, that's the bit i was unsure of
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    (Original post by Jorgeyy)
    Looks pretty good to me, I probably wouldn't even mention the pharynx myself just that water is drawn in and forced out over the gills ^^
    ok thank you
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    (Original post by DoaaK)
    what are the coronary arteries? D:
    Blood vessels that supply the heart muscles with oxygenated blood.
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    (Original post by ryan02)
    Is the cohesion, in cohesion tension theory, caused by hydrogen bonds or Van der Waals'?
    cos the text book says hydrogen, but i'm sure my teacher told us it was Van der Waals' :/

    and could someone try explain root pressure to me?

    thanks!
    Hydrogen bonds. Save van der waals for Chemistry :P
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    (Original post by DoaaK)
    what are the coronary arteries? D:
    are they not just the Vena Cava, and the Aorta? otherwise i'm stuck too :/
 
 
 
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