AQA Biology AS New Spec - 26th May and 7th June

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    (Original post by Whatevenemily)
    What ****ed me over in the specimen papers we've had for the new specification was how strict the mark scheme was! I literally know the majority of the content but I just don't write answers in the way they want me to 😡 It's so annoying. I've basically just accepted that I'm getting a U in these exams no matter what the paper or the grade boundaries are🙄
    I literally feel the exact same way. I had a mini breakdown today because no matter what I do I can't seem to get the wording correct, and have ended up with a U on ALL my practice papers this year.
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    We did a mock in school a few weeks ago, which was one of the specimen papers that aren't disclosed to the students so I can't find the answers anywhere.

    Just realised I didn't mark one of the questions properly. Please help

    Q) In a eukaryotic cell, transcription results in a molecule of pre-mRNA that is modified to produce mRNA. In a prokaryotic cell transcription produces mRNA directly. Explain this difference.

    I know that it's to do with the complexity of eukaryotic cells but don't know exactly what the answer should have.
    Any help greatly appreciated!
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    Predictions for tomorrow??
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    After transcription in Eukaryotic cells pre-mRNA needs to be modified because it contains introns (part of the gene which don't code for a polypeptide). The introns are therefore 'spliced' (removed) out of the sequence, only leaving exons(parts of the mRNA sequence which do code for poypeptides) in the final mRNA .The entire sequence of mRNA in prokaryotes code directly for polypeptides and so do not need to be modified.
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    (Original post by Namita Gurung)
    We did a mock in school a few weeks ago, which was one of the specimen papers that aren't disclosed to the students so I can't find the answers anywhere.

    Just realised I didn't mark one of the questions properly. Please help

    Q) In a eukaryotic cell, transcription results in a molecule of pre-mRNA that is modified to produce mRNA. In a prokaryotic cell transcription produces mRNA directly. Explain this difference.

    I know that it's to do with the complexity of eukaryotic cells but don't know exactly what the answer should have.
    Any help greatly appreciated!
    I'm not entirely sure and i'm might be missing out important points, but prokaryotic cells don't have non-coding DNA, so splicing/modifying doesn't need to occur, meaning it produces the mRNA directly. This is unlike transcription in a eukaryotic cell as these cells contain introns (non-coding parts of the DNA) within and between genes which must be edited/spliced out but cannot be spliced out immediately as the entire molecule has to be transcribed (There's no way around this) resulting in pre-mRNA. The depth it wants depends on the number of marks, but i think the basis is that prokaryotic DNA doesn't have non-coding sections, so the mRNA is directly made.

    Edit - I typed this out without realising someone had already replied, sorry for the repeat :3
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    (Original post by olievans)
    After transcription in Eukaryotic cells pre-mRNA needs to be modified because it contains introns (part of the gene which don't code for a polypeptide). The introns are therefore 'spliced' (removed) out of the sequence, only leaving exons(parts of the mRNA sequence which do code for poypeptides) in the final mRNA .The entire sequence of mRNA in prokaryotes code directly for polypeptides and so do not need to be modified.

    (Original post by Laurenloops)
    I'm not entirely sure and i'm might be missing out important points, but prokaryotic cells don't have non-coding DNA, so splicing/modifying doesn't need to occur, meaning it produces the mRNA directly. This is unlike transcription in a eukaryotic cell as these cells contain introns (non-coding parts of the DNA) within and between genes which must be edited/spliced out but cannot be spliced out immediately as the entire molecule has to be transcribed (There's no way around this) resulting in pre-mRNA. The depth it wants depends on the number of marks, but i think the basis is that prokaryotic DNA doesn't have non-coding sections, so the mRNA is directly made.
    Thank you both! It makes sense to me
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    (Original post by Namita Gurung)
    We did a mock in school a few weeks ago, which was one of the specimen papers that aren't disclosed to the students so I can't find the answers anywhere.

    Just realised I didn't mark one of the questions properly. Please help

    Q) In a eukaryotic cell, transcription results in a molecule of pre-mRNA that is modified to produce mRNA. In a prokaryotic cell transcription produces mRNA directly. Explain this difference.

    I know that it's to do with the complexity of eukaryotic cells but don't know exactly what the answer should have.
    Any help greatly appreciated!

    In eukaryotes, the introns and exon are both copied into mRNA during transcription. mRNA strands containing introns and exons are pre-mRNA. In pre-mRNA splicing occurs to remove the introns which are non-coding. Whereas, in prokaryotes, mRNA is produced directly from the DNA,without splicing-splicing is not needed due to there being no introns in prokaryotic DNA.
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    (Original post by rumana101)
    In eukaryotes, the introns and exon are both copied into mRNA during transcription. mRNA strands containing introns and exons are pre-mRNA. In pre-mRNA splicing occurs to remove the introns which are non-coding. Whereas, in prokaryotes, mRNA is produced directly from the DNA,without splicing-splicing is not needed due to there being no introns in prokaryotic DNA.
    Thank you!
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    mass transport system of the heart
    Can anyone explain this to me plzzz?
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    ***********************PLEASE HELP******************

    WHAT TIME IS THE EXAM

    aqa biology as paper 2

    please reply ASAP
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    (Original post by asdfghk13)
    ***********************PLEASE HELP******************

    WHAT TIME IS THE EXAM

    aqa biology as paper 2

    please reply ASAP
    13:30 pm
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    thanks soooooooooooooooooooooo much , now i have an extra 4 hours to revise in the morning so going to have a good nights sleep
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    ive got it half 9
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    (Original post by Zain khan)
    ive got it half 9
    how? isn't everyone supposed to have It same time?
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    did anyone give paper 1 CIE AS for bio?
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    I thought everyone had it around half 1 so answers can't be leaked :confused:
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    (Original post by Productivity)
    Attachment 544573
    Edit: the value is a minus as the gradient is negative.
    It's a negative gradient so the answer needs to have a minus in front.
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    I have it at 13:45...
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    (Original post by allxcey)
    Predictions for tomorrow??
    well nothing on chapters 6-10 came up in the first paper.
    it was 1-5 even though it shouldnt have. im only revising 6-10
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    (Original post by Collombia)
    I have it at 13:45...
    Are you sure?...
 
 
 
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