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AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011 watch

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  • View Poll Results: Are you resitting this unit?
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    (Original post by Destroyviruses)
    Thanks.

    But what I want to know is what happens after the virus enters the body cells.
    it inserts its DNA into the host DNA.

    Thus it is transcribed and translated like a normal gene.
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    Does anyone have any copies of model essays? I could do with looking at a few examples.
    I'm just a bit confused about what style we're supposed to write the essay in. Are we writing it as if we're explaining the topic to somebody who knows nothing about biology (eg. should we be defining the technical words we use and stuff) or are we writing it for a biology expert? Because I don't want to waste time writing definitions and stuff if we wouldn't even be marked for it. :/
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    (Original post by Sparkly-Star)
    Is the bit you learn about the neuromuscular junctions in muscles the same as the choligernic synapse in the nervous system chapter?
    Almost. Muscles are arranged as motor units - several muscle fibres supplied by a single motor neurone, allowing control over the force the muscle exerts. The release of Ach and its mode of action are the same.
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    (Original post by flowerscat)
    The one about A-bands and I bands?
    Yeah
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    (Original post by -Iffy-)
    Eek, exam in less than 22 hours :eek: I feel like I'm forgetting/forgotten all the stuff I learnt :/ Well I hope that the grade boundaries are low like last year, possible even lower if we're lucky
    what were last years grade boundaries for an A, do you know?
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    (Original post by flowerscat)
    Because you are adding four terminator nucleotides.

    The synthesis of the completmentary base to the first base of the sequence can be either by a "normal" base or a terminator base.

    If the terminator base is added, then the first band will correspond to one nucleotide.

    In practice, this does not happen, as you will also have the sequence of the (radiolabelled) primer to account for. So the lowest band = (length of primer + first base)

    Hope this helps.
    yes thanks this is more clear
    but it can also be : length of primer + 4 normal bases + terminator nucleotide
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    (Original post by Vidja)
    Oh, really? Thanks. Is it the actual carbonic acid molecule that displaces the oxyegn, or does a CO from the acid displace it or something?

    EDIT: The textbook says the low pH of the acid causes the haemoglobin to change shape?
    carbonic acid dissociates into hydrogen carbonate ions and H+ ions. H+ ions lower pH. To prevent too drastic a change in pH haemoglobin acts as a buffer. It releases the oxygen and takes up the H+ ions to form haemoglobinic acid. So it does change shape to bind to H+ but does not denature.

    85% of the CO2 generated via muscle respiration is transported as carbonic acid via the blood plasma to the lungs, where it denatures and releases CO2 into the lungs.
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    (Original post by M.A.)
    what were last years grade boundaries for an A, do you know?
    62/100, so 62% and 69% for an A*
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    (Original post by flowerscat)
    carbonic acid dissociates into hydrogen carbonate ions and H+ ions. H+ ions lower pH. To prevent too drastic a change in pH haemoglobin acts as a buffer. It releases the oxygen and takes up the H+ ions to form haemoglobinic acid. So it does change shape to bind to H+ but does not denature.

    85% of the CO2 generated via muscle respiration is transported as carbonic acid via the blood plasma to the lungs, where it denatures and releases CO2 into the lungs.
    Thanks. You've just made a potential essay sound a little more impressive haha.
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    (Original post by flowerscat)
    carbonic acid dissociates into hydrogen carbonate ions and H+ ions. H+ ions lower pH. To prevent too drastic a change in pH haemoglobin acts as a buffer. It releases the oxygen and takes up the H+ ions to form haemoglobinic acid. So it does change shape to bind to H+ but does not denature.

    85% of the CO2 generated via muscle respiration is transported as carbonic acid via the blood plasma to the lungs, where it denatures and releases CO2 into the lungs.
    Woo thats pretty cool, I never knew that. We were always taught that it just denatured it by breaking the hydrogen bonds. Well the hydrogen bonds would break so I guess its vaguely right.
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    (Original post by Sparkly-Star)
    Yeah
    A-band = length of myosin filament
    I-band = length of actin filament
    H-zone = gap in the overlap regions

    Possibilities of muscle contraction:

    Actin and myosin both contract
    Myosin slides over actin
    Actin slides over myosin
    Some other mechanism results in contraction

    Experimental evidence has shown the size of the A-band does not change during contraction, but the size of the I-band and H-zone does. The most likely explanation for this is that myosin remains stationary, while action slides over myosin.
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    HEY! Was just wondering is there anyway to calculate what i need to get in BIOL5 to get a mark overall? Can someone explain that to me please!

    Also, anyone have any synoptic essay plans that they are willing to lend!?
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    how many marks would 120UMS be?
    and also 80UMS?
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    can someone help me with gene sequencing please?!?!?!
    really confused about it! :'(
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    Is there any point knowing about T - Tubulus? I haven't seen anything about it in exam questions. =/
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    any guesses on tomorws essay question?
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    Hey, I haven't even attempted a synoptic essay yet and I have no idea what can come up. There's no way I can look over other units now as I'm still doing unit 5, but does anyone pleeease have a list of essay plans or something? I'm sure there are some in this thread but I tried trawling through 74 pages and it's pretty tough!
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    (Original post by M.A.)
    what were last years grade boundaries for an A, do you know?
    69/100 - A*
    62/100 - A
    55/100 - B

    Don't remember the others.
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    (Original post by RMS184)
    HEY! Was just wondering is there anyway to calculate what i need to get in BIOL5 to get a mark overall? Can someone explain that to me please!

    Also, anyone have any synoptic essay plans that they are willing to lend!?
    Your AS UMS is out of 300, A2 practical out of 60 and Unit 4 100, Unit 5 140 so altogether 600 UMS for full A-Level.

    You know your AS marks but the rest will depend on grade boundaries...
    Overall

    480/600 A
    420/600 B and so on
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    carpet 21... you know there are loads of things in unit 5 which you can use for the synoptic esssay. so dont worry about it exessively... but wat im learning from as, is like cholera, cohesion tension theory, phagocytosis... stuff which apply to many things ... and u must learn photosynthesis and respiration and nitrogen cycle from unit 4. kindov a must. applies to manyyyyyyyyy essays
 
 
 
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