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

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    (Original post by chjw)
    what did everyone put for the question where it asked about why percentage bases at middle and end are different? the only one I really couldn't do!
    yeah, i didn't get this question either???
    what answers did everyone put down for this?
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    I know this is a really stupid question, but did you have to write down which question you were answering??
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    (Original post by Rainbow249)
    Active transport, but not too sure! But I spoke to one of my teachers, and he said diffusion and active transport was possible, depending on where it happens.

    What exactly was the question, does anyone remember?
    The question was "How does IAA travel from the shoot tip to other tissues in the plant?"

    I'm pretty sure the answer is diffusion. It is only actively transported from one side to the other, in phototropism.
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    (Original post by Black Butler)
    Hey, I just wanted to see if anyone else had the same idea as me about the IAA with temperature and why the underside of the leaf has higher IAA with increasing temperature.

    I put down that it allows the leaf to curl up and so there is less water vapour lost as the diffusion gradient of water decreases.
    But didn't they ask about the UPTAKE of IAA ?
    I put down that the higher the temp the higher the transpiration rate. Water loss increases by evaporation, so stomata are opened for much longer to allow gas exchange, hence more IAA is taken into the leaf ?
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    (Original post by JeevesFTW)
    The question was "How does IAA travel from the shoot tip to other tissues in the plant?"

    I'm pretty sure the answer is diffusion. It is only actively transported from one side to the other, in phototropism.
    I wrote tropism for that part. I was tempeted to write geotropism though.
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    (Original post by amysoolz)
    yeah, i didn't get this question either???
    what answers did everyone put down for this?
    I put that the different areas contain different genes, so different base sequence, so different proportions.

    (Original post by laura123)
    I know this is a really stupid question, but did you have to write down which question you were answering??
    If your essay was at all relevant, it should be clear which one you are answering.
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    (Original post by RodrigoB)
    But didn't they ask about the UPTAKE of IAA ?
    I put down that the higher the temp the higher the transpiration rate. Water loss increases by evaporation, so stomata are opened for much longer to allow gas exchange, hence more IAA is taken into the leaf ?
    IAA is used to elongate cells or stretch parts. At higher temperature is specifically the underside of the leaf used more of the hormone - it would curl up and so allow a smaller diffusion gradient for water vapour to be lost from the stomata.
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    (Original post by Black Butler)
    I wrote tropism for that part. I was tempeted to write geotropism though.
    I wrote...


    taxis. :teeth:


    I know I know... LOL
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    (Original post by Black Butler)
    Hey, I just wanted to see if anyone else had the same idea as me about the IAA with temperature and why the underside of the leaf has higher IAA with increasing temperature.

    I put down that it allows the leaf to curl up and so there is less water vapour lost as the diffusion gradient of water decreases.
    I put that increased temperature = increased kinetic energy of molecules, so more rapid diffusion, so faster uptake. Simples.
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    (Original post by Black Butler)
    IAA is used to elongate cells or stretch parts. At higher temperature is specifically the underside of the leaf used more of the hormone - it would curl up and so allow a smaller diffusion gradient for water vapour to be lost from the stomata.
    that totally makes sense.
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    (Original post by JeevesFTW)
    I put that increased temperature = increased kinetic energy of molecules, so more rapid diffusion, so faster uptake. Simples.
    no this is the question about why the uptake of IAA was greater on the underside of the leaf at higher temperature.
    What I wrote should make sense.
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    I thought for the IAA uptake question, more IAA was taken up at higher temperatures because the stomata under the leaf open up more to allow excess heat to escape, and this opening of the stomata increases the size of the pores which means IAA can be taken up faster, as the hole is larger.
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    (Original post by Black Butler)
    no this is the question about why the uptake of IAA was greater on the underside of the leaf at higher temperature.
    What I wrote should make sense.
    Wait... Is it asking about the effect of temperature on the uptake into the underside of the leaf, or about why the underside takes up more regardless of temperature?
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    (Original post by amysoolz)
    yeah, i didn't get this question either???
    what answers did everyone put down for this?
    There will be different genes in the middle and end of the chromosomes, which means there will be different sequence of bases, so % of specific base will be different.
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    [QUOTE=JeevesFTW;32391101]I put that the different areas contain different genes, so different base sequence, so different proportions.

    ahh okay thankss. i wrote something along those lines i think: different parts of the dna has different base seqs but then i cant remember what else. i think i wrote something about mRNA lol...
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    (Original post by RodrigoB)
    that totally makes sense.
    Thanks. I couldnt see why at first the the under side of the leaf is much more sensitive to temperature increase. I left it out and went back and something clicked from AS biology.
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    i didn't write down the question number i was writing? will my essay still be marked?!?
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    (Original post by JeevesFTW)
    Wait... Is it asking about the effect of temperature on the uptake into the underside of the leaf, or about why the underside takes up more regardless of temperature?
    It asked why the underside of the leave's uptake of IAA increased with higher temperatures.
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    (Original post by Rainbow249)
    There will be different genes in the middle and end of the chromosomes, which means there will be different sequence of bases, so % of specific base will be different.
    Exactly what I said - the gene is different and so has a different sequence of bases.
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    (Original post by percy93)
    i didn't write down the question number i was writing? will my essay still be marked?!?
    If you wrote your essay well, it should be obvious. I started my intro with something like 'Cycles are found in nearly all aspects of biology....'. Take a guess which one I did.
 
 
 
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