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    Hey people. only a weekend left now
    Good luck to all of you,
    Im hoping for an E overall - poor, I know right
    Any tips on whats best to do and look over as Im clueless
    Many thanks, and again good luck everyone,
    (btw I find it extremely hard to revise)
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    Yeh, if they ask you synoptic questions it tends to be a couple of marks and fairly straightforward things or sometimes they say compare a process in this module e.g. PCR to a process we covered last year
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    Hiya, Don't worry about it just try your best. I would advise you look over some of the big topics which are very likely to come up. For example genetic engineering, biotechnology and meiosis. Good Luck
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    Do we need to know about :
    Apical/ lateral bud/ lateral/intercalary meristems?
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    (Original post by sportycricketer)
    lol my teacher too, and everyone on the thread do you think it's worth looking over last year's biology's Conservation module, theres so much to revise in this module anyway
    I think its worth a read over, but so much in this unit I wouldn't spend too much time on it
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    Yeh, I'm looking at tons of past paper questions. Plant questions are the bain of my life!
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    (Original post by twelve)
    Okay, in a cell, you're right - you have a paternal chromosome and a maternal chromosome. In interphase, they look like this:
    | |

    Then, in interphase, they replicate so that they look like this:
    X X

    In prophase, those two homologous chromosomes line up and form the bivalent like you said. They'll cross over, and the genes will get all mixed up ready for the divisions.




    For the haploid/diploid thing, I think about it as a cycle:

    Adult human - 2n ||
    a chromosome from the mother, and one from the father
    |
    |
    v
    Gametes - n |
    meiosis occurs, so that there is only half the genetic material - this will be a mixture of genes from the individuals parents
    |
    |
    V
    Zygote - 2n | |
    gametes from the two parents join together, and then it starts again.
    I think I'm in love. Thank you!

    So when you have:

    X X, and then they line up, so when they get pulled away it have either the replicated pair from the mother, or from the father? With the chiasma, if any have crossed.

    I then don't quite understand how independent assortment comes into play, well, ish. So if there were say, 5 pairs of chromosomes, so you'd have 5 bivalents? then in the first division you could get any combination of maternal/paternal chromosomes in each?

    And finally, I promise it's becoming clearer, the difference between the chromosome/chromatid? Is the chromosome the X, and the chromatid is one half of the X? Then in the second division it's just the chromatids being pulled to each pole, as opposed to an X?

    Thanks
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    (Original post by Kidms001)
    The ones endorsed by OCR. Surely if they are endorsed by OCR, then they are the correct ones (or so my teacher likes to bang on about)

    Do the exam board print their own definitions?
    I was just going to ask you that question, hence the first one lol.
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    (Original post by Kaph)
    I think I'm in love. Thank you!

    So when you have:

    [COLOR="Red"]X[/COLOR] [COLOR="Blue"]X[/COLOR], and then they line up, so when they get pulled away it have either the replicated pair from the mother, or from the father? With the chiasma, if any have crossed.
    Yep - when they get pulled away, one chromosome from ecah homologous pair goes to each pole. With the crossed over parts etc. BUT, its one chromosome pulled to each end, not pair. They are a pair of chromosomes when they are lined up next to eachother, but only one is pulled to each end.


    (Original post by Kaph)
    I then don't quite understand how independent assortment comes into play, well, ish. So if there were say, 5 pairs of chromosomes, so you'd have 5 bivalents? then in the first division you could get any combination of maternal/paternal chromosomes in each?
    We'll use the crosses again:
    X X
    X X
    X X
    X X


    If you have four chromosomes, they could arrange themselves like that ^ or they could arrange themselves as below. So once they are pulled apart, there will be different chromosomes in each of the new cells.


    X X

    X X
    X X
    X X


    Independant/random assortment is the way of saying they go into the middle, but it doesn't matter what order, or what side the maternal/paternal chromosomes are on.


    (Original post by Kaph)
    And finally, I promise it's becoming clearer, the difference between the chromosome/chromatid? Is the chromosome the X, and the chromatid is one half of the X? Then in the second division it's just the chromatids being pulled to each pole, as opposed to an X?

    Thanks
    Yep, chromosome is X OR | before it has replicated.

    And the chromatid is just one half of the X, so each chromosome (when replicated) has two chromatids.

    In the second division, one chromatid is pulled to each pole, BUT when its separated, its called a chromosome again. So when its part of an X, the > is called a chromatid, but once its separate, its called a chromosome.
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    Can someone tell me why on modernisation online it seems to have written CHANGED under F214 and F215 and they no longer come up under the normal search only when specified by their keys??? I'm pretty sure this was done recently and I'm worried they might have done something to the exams we're going to be sitting in a couple of days.
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    (Original post by Arab_Empress)
    Hey all,

    I know the function of restriction endonuclease and what it does etc and I know it targets the restriction site on an DNA section, BUT does the enzyme have a complementary base sequence to the restriction site which has a specific base sequence (like DNA probe), or is it like all enzymes and has a particular active site and nothing to do with bases?
    no no no, restricion enzymes are just like any other enzyme, they don't have bases.
    And it wouldn't make sense them having coplementary bases as DNA is double stranded so it wouldn't have any un-bonded bases to bind to.
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    I know its extremely hard to tell/predict, but does anyone have any ideas on what they think might come up on monday?
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    (Original post by There will be Particles)
    Can someone tell me why on modernisation online it seems to have written CHANGED under F214 and F215 and they no longer come up under the normal search only when specified by their keys??? I'm pretty sure this was done recently and I'm worried they might have done something to the exams we're going to be sitting in a couple of days.
    Relax, it's fine - it just happens on the system i think lol

    btw, i was meaning to ask - what's your signature about?
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    (Original post by NWA)
    I know its extremely hard to tell/predict, but does anyone have any ideas on what they think might come up on monday?
    I have no clue but I'm guessing, hoping a long question on comparing continuous and batch culture, stuff on immobilising enzymes, secondary and primary metabolites. long genetic engineering question and some stuff on the brain and nervous system.
    Maybe meiosis- really have no clue
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    (Original post by twelve)
    Yep - when they get pulled away, one chromosome from ecah homologous pair goes to each pole. With the crossed over parts etc. BUT, its one chromosome pulled to each end, not pair. They are a pair of chromosomes when they are lined up next to eachother, but only one is pulled to each end.




    We'll use the crosses again:
    X X
    X X
    X X
    X X


    If you have four chromosomes, they could arrange themselves like that ^ or they could arrange themselves as below. So once they are pulled apart, there will be different chromosomes in each of the new cells.


    X X

    X X
    X X
    X X


    Independant/random assortment is the way of saying they go into the middle, but it doesn't matter what order, or what side the maternal/paternal chromosomes are on.




    Yep, chromosome is X OR | before it has replicated.

    And the chromatid is just one half of the X, so each chromosome (when replicated) has two chromatids.

    In the second division, one chromatid is pulled to each pole, BUT when its separated, its called a chromosome again. So when its part of an X, the > is called a chromatid, but once its separate, its called a chromosome.
    You are brilliant, thank you. I think part of the reason I'm confusing myself is because I'm calling each chromosome, like each X, a chromosome pair, but XX a chromosome pair as well. That definitely didn't help things aha.

    It's all much clearer now; again thank you.
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    Anyone think Primary and secondary productivity will come up again as there was alot about it in Jan 2011?
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    Does anyone have the Jan 2011 mark scheme, please?
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    Someone please please please explain LINKED GENES!!! and how they work in a cross?
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    (Original post by Bullit)
    no no no, restricion enzymes are just like any other enzyme, they don't have bases.
    And it wouldn't make sense them having coplementary bases as DNA is double stranded so it wouldn't have any un-bonded bases to bind to.
    Ahh Thanks
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    (Original post by subsist)
    Someone please please please explain LINKED GENES!!! and how they work in a cross?
    Yeah I didnt quite get it either, the example in the book is quite confusing
 
 
 
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