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    (Original post by Bullit)
    You've got it easy mate. I have one offer for AAA, no back up.
    Haven't got backup either... I need to get a C to get A overall... need AAA for med
    wat do u need in this exam to get an A overall?
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    (Original post by heartskippedabeat)
    Aw good luck
    thanks
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    (Original post by greenford)
    Haven't got backup either... I need to get a C to get A overall... need AAA for med
    wat do u need in this exam to get an A overall?
    An A, might be able to get away with a high B but I haven't had any really high As so not got much room for error.

    Kudos on having no backup. ALL OR NOTHING! haha
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    drosophila anyone?

    the whole mitosis division about it confuses me
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    (Original post by Bullit)
    An A, might be able to get away with a high B but I haven't had any really high As so not got much room for error.

    Kudos on having no backup. ALL OR NOTHING! haha
    Same situation here :/
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    I don't have a backup either, it's scaryy :/
    Although it's my fault for being fussy and only wanting to go to one uni
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    (Original post by YuDunno)
    Okay great

    plant responses/hormones/auxin..

    anything.

    don't have a clue about this unit
    Haha, sure

    ----

    Plants respond to there enviroment to avoid predation and abiotic stress, so that they are able to photosynthesize effectively and survive.

    Plants respond through tropisms, a tropism is a directional growth response of a plant determined by the direction of the external stimulus.

    To produce a tropism, a plant produces growh hormones or plant growth substances. These are hormones which are released by specific parts of the plant to bind to target cells to initiate a response > due to the receptor having a complimentary shape for the hormone to bind to, and trigger an effect.

    Auxins

    -Produces in the apical bud(the apex) of the shoot tip in the plant
    -Involved in cell elongation, stem elongation and also preventing leaf abcission.

    Auxin is also involved in a phototrophic response, this response happens because, as light hits the plant, the apical bud produces auxins that are able to flow down the shaded side(the side of the plant that is not exposed to the sun). Auxin causes cell elongation by helping in the active transport of hydrogen ions into the cell wall, this allows optimum pH for expansioners to work, these expansioners are able to break the bonds between cellulose(which are going to be glycosidic bonds i believe) and so the plant is able to take in water, causing elongation.
    This then means that the shoot bends towards a light source.

    Auxins are also involved in apical dominance, the growing apical bud inhibits the groth of the lateral bud(side shoots) further down the plant. It's been tested experimentally, because if you remove apical bud of a plant, side shoots are able to grow. If you apply synthethic auxin once you've removed the apical bud, side shoots don't grow.

    Gibberlinnins - need to know a bit about them, just that they cause internodal stem elongation which has been tested experimentally, by applying synthethic GA (gibberlillic acid) to dwarf varities of plants, your able to produce tall plants > this is useful in sugar cane crops, so GA is applied.


    Leaf abcission/leaf fall in decidicous plants


    This is caused by a variety of hormones.

    -Auxin prevents leaf loss by acting on the cells of the abcission zone, but as the cell gets older, the auxin concentration decreases

    -As auxin conc decreases, concentration of Ethene increases, working antagonistically - ethene causes enzymes (cellulase) to digest the cell wall of the cells in the abcission zone > which means the leaf seperates from the stem

    -Cytokinins are also involved, they prevent leaf loss by making the cells in the abcission zone a sink for phloem transport, so get's a good supply of nutrients, e.g sucrose.

    Commercial use of plant hormones

    Auxins can be applied to fruit trees to prevent fruit from dropping early, auxin is also used as a herbicide as it causes cell elongation, and also increases the length of the stem > this means that the plant will need to take up more nutrients from which it can't get and so will die.

    Auxins can be used as rooting powder, as they promote seed germination i think

    Gibberlennins are used in the brewing process (forgot how)
    Gibberlniegnegns are used to produce long internode crops e.g sugar cane

    Cytokinins - can be applied to plants to prevent leaf fall

    Ethene - can be applied to plants to allow them to fall earlier, this applies to bannanas which are sprayed with ethene, so when they are packaged and sold - they ripen.

    that's all of plant responses done.. woo
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    (Original post by sillysal)
    drosophila anyone?

    the whole mitosis division about it confuses me
    you don't need to know much about drosphilla, just know that it has homeobox genes which control development of body plans, these are arranged in hox clusters. Homeobox genes code for various transcription factors, including homeodomain which is able to start/stop transcription of various genes that control development of body plans.
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    (Original post by Waqar Y)
    you don't need to know much about drosphilla, just know that it has homeobox genes which control development of body plans, these are arranged in hox clusters. Homeobox genes code for various transcription factors, including homeodomain which is able to start/stop transcription of various genes that control development of body plans.
    oh i see thankyou! so page 114 in the heinemann book the bits about how it develops we don't need to know?
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    Where can I find the specimen paper?
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    And the jan 11 please lol
    • Study Helper
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    Study Helper
    (Original post by joestevens2092)
    And the jan 11 please lol
    http://www.scribd.com/doc/53218531/f215-jan-2011-paper
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    We're just 48 hours away from this exam!
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    anybody got any questions? (i find it helpful for revision to answer)
    also does anybody know if we need to know about sickle cell anaemia in detail?
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    in genome sequencing, does electrophoresis happen before or after automated sequencing?

    and THEN the computer is used to compare overlapping regions of fragment to put together genome?
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    (Original post by sillysal)
    in genome sequencing, does electrophoresis happen before or after automated sequencing?

    and THEN the computer is used to compare overlapping regions of fragment to put together genome?

    Before isn't it?



    Electrophoresis --- > PCR ---- > automated sequencing



    can anyone one tell me where DNA probes come into this? Oh and I dont understand Chi Squared at all
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    (Original post by intellectual1)
    We're just 48 hours away from this exam!
    :eek:
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    (Original post by sillysal)
    in genome sequencing, does electrophoresis happen before or after automated sequencing?

    and THEN the computer is used to compare overlapping regions of fragment to put together genome?
    by automated sequencing do you mean where the 'tag nucleotides' bind to the end of the dna fragments? if you do yes, electrophoresis happens after because the nucleotides 'tagging' the dna fragments means that theres lots of different lengths (because of the fact they are doubly deoxidised.) so once theres lots of different lengths, electrophoresis is used to identify the different lengths and the tag colour is recorded as they each pass through a 'window'. then the computer will basically record the colours in sequences so that it can be sequenced.
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    if there is a question on gene sequencing...
    Do we talk about BAC and then sequencing..... or just sequencing
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    (Original post by gkaur123)
    by automated sequencing do you mean where the 'tag nucleotides' bind to the end of the dna fragments? if you do yes, electrophoresis happens after because the nucleotides 'tagging' the dna fragments means that theres lots of different lengths (because of the fact they are doubly deoxidised.) so once theres lots of different lengths, electrophoresis is used to identify the different lengths and the tag colour is recorded as they each pass through a 'window'. then the computer will basically record the colours in sequences so that it can be sequenced.
    thankyou for clearing that up for me!
 
 
 
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