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Edexcel 6BIO1 ~ 9th January 2013 ~ AS Biology

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    (Original post by Rubyturner94)
    hey guys,
    can someone explain the effect of cf on the gas exchange (respiretory system)? [4]


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    - Mucus in sufferers of CF is thick and sticky
    - Thickened mucus can't be moved by cilia/coughing
    - Mucus blocks airways
    - Gas exchange reduced
    - because surface area is reduced
    - so diffusion decreases
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    thank you
    when they ask to ''describe the structure of enzymes'' do we descibe the 3-dimensional structure? eg chemical bond between R groupa etc?

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    (Original post by Rubyturner94)
    thank you
    when they ask to ''describe the structure of enzymes'' do we descibe the 3-dimensional structure? eg chemical bond between R groupa etc?

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    Yes and no. The mark scheme says this.

    globular / eq ; (NOT 3D.)
    2. reference to active site ;
    3. reference to specific shape of active site ;
    4. reference to {bonds /named bond / interaction / eq} between R groups ;
    5. credit correctly named {bond/interaction} e.g. disulphide bond, hydrogen bonds, hydrophobic interactions (between R groups) ;
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    Just did the June 2010 paper, and I'm a bit disappointed with my mark (62/80). Even though it was an A, I made stupid mistakes getting 0 marks in 3 parts.
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    (Original post by mynameisntbobk)
    Just did the June 2010 paper, and I'm a bit disappointed with my mark (62/80). Even though it was an A, I made stupid mistakes getting 0 marks in 3 parts.
    That was my worst paper I think I got 60 in it. I just found some of the questions odd!
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    (Original post by Kingboss)
    That was my worst paper I think I got 60 in it. I just found some of the questions odd!
    It really was a bad paper, and a lot of the questions were, nonsense to say the least. And the way they worded it aswell was bad.
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    sorry to bother you again :/ (really do hate enzymes)
    can someone explain this question to me.
    explain how the 3D structure of proteins enable enzymes to perform their functions as biological catalysts?
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    (Original post by Rubyturner94)
    sorry to bother you again :/ (really do hate enzymes)
    can someone explain this question to me.
    explain how the 3D structure of proteins enable enzymes to perform their functions as biological catalysts?
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    Enzymes are globular proteins.

    They have an active site

    The active site is specific for a certain type of substrate.
    The substrate binds in the active site

    The shape of the enzyme changes slightly (induced fit)

    An enzyme-substrate complex is created.

    A reaction occurs..

    The porduct(s) leaves the active site

    *Less energy is needed for the reaction- activation energy decreases
    *Enzymes speed up the rate of reaction
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    thanks hows revision going guys? :/

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    can someone help me on question 2ci in june 2011. I thought that Elina is recessive has the disease so wouldn't her alleles be gg as she has galactosaemia. This appears to be wrong can some explain this
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    (Original post by Rubyturner94)
    thanks hows revision going guys? :/

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    Going good
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    (Original post by Kingboss)
    can someone help me on question 2ci in june 2011. I thought that Elina is recessive has the disease so wouldn't her alleles be gg as she has galactosaemia. This appears to be wrong can some explain this
    Not wrong.

    Galactosaemia is recessive. So if Sahan is a carrier:

    Then Sahans genotype is : Gg
    and Elinas: gg

    Do a genetic diagram from that and work out percentage that the child is heterozygous. pretty staight forward if you ask me.
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    (Original post by CoolRunner)
    Not wrong.

    Galactosaemia is recessive. So if Sahan is a carrier:

    Then Sahans genotype is : Gg
    and Elinas: gg

    Do a genetic diagram from that and work out percentage that the child is heterozygous. pretty staight forward if you ask me.
    It was straight forward and that's what I did, but the examiners' report showed Elina as GG and the candidate still got three marks.. and that made me wonder
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    (Original post by Kingboss)
    It was straight forward and that's what I did, but the examiners' report showed Elina as GG and the candidate still got three marks.. and that made me wonder
    LOL! the examiner did not mark properly.:rolleyes:
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    (Original post by Kingboss)
    It was straight forward and that's what I did, but the examiners' report showed Elina as GG and the candidate still got three marks.. and that made me wonder
    Just looked at the exam report. that q was a 4 marker, the candidate got 3 marks for everything else but just the GG wrong. some how its a coincidence as you get the same answer even if you do that mistake.
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    (Original post by CoolRunner)
    Just looked at the exam report. that q was a 4 marker, the candidate got 3 marks for everything else but just the GG wrong. some how its a coincidence as you get the same answer even if you do that mistake.
    Lol yeah it is that candidate was lucky though that might have not been the case in another question. I also wonder how the student thought it was GG when she was clearly in bold
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    (Original post by Kingboss)
    Lol yeah it is that candidate was lucky though that might have not been the case in another question. I also wonder how the student thought it was GG when she was clearly in bold
    Same here :s
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    So I just did the June 2009 paper which was shockingly hard, although I got 58. The grade boundaries for it were so low as well, you needed 49/80 for an A. I hope our paper has grade bondries like this, but I hope the content is easier.
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    (Original post by mynameisntbobk)
    So I just did the June 2009 paper which was shockingly hard, although I got 58. The grade boundaries for it were so low as well, you needed 49/80 for an A. I hope our paper has grade bondries like this, but I hope the content is easier.
    lol that wouldn't happen easy content means high grade boundary. But we can all hope
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    (Original post by Kingboss)
    lol that wouldn't happen easy content means high grade boundary. But we can all hope
    Yeahh, only hope
    But don't you think 49 is mad for an A. I was shocked doing that exam because I was so pushed for time.
Updated: May 21, 2013
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