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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011 watch

  • View Poll Results: Are you resitting this unit?
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    (Original post by Robert McGeachan)
    Does anyone have or know how to get hold of the old specification past papers for unit two?????
    http://freeexampapers.com/past_paper...s%2FA+Level%2F
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    (Original post by xkate1019x)
    Heyy can anyone clarify if this is right? i'm having a

    Interphase - Dna is replicated
    Prophase - Spindle forms
    **Metaphase - Chromosomes line up at the centromere of the cell
    **Anaphase - Spindle fibres shorten and pull chromatids to opposite poles
    Telophase - 2 identical cells are formed

    & mitosis is needed for Growth, Repair and Differentiation?
    :ff2:
    In metaphase chromosomes do not line up at the centromere of the cell they line up at the equator of the cell. Then the centromere of the chromosome is attached to a spindle fibre.

    In anaphase the spindle fibres contract and not shorten, you could have lost marks for incorrect terminology.

    Its just that, that made me think alot, you were quite right after all.:rolleyes:
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    (Original post by therapist_1)
    :ff2:
    In metaphase chromosomes do not line up at the centromere of the cell they line up at the equator of the cell. Then the centromere of the chromosome is attached to a spindle fibre.

    In anaphase the spindle fibres contract and not shorten, you could have lost marks for incorrect terminology.

    Its just that, that made me think alot, you were quite right after all.:rolleyes:
    Thankyou gosh i'm dreading this exam lol!
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    (Original post by al_habib)
    hows revision,,
    Going good for bio not other subjects wa bou u?
    u prepared for this thursdaii
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    Haemoglobin

    Are my Facts correct? I'm a bit unsure on my termonology...

    - Haemoglobin is a protein
    - It is made up of 4 polypeptide chains (quartenary structure)
    - Each polypeptide has a haem group (non protein ), which contains iron
    - It is hard for oxygen to bind with haemoglobin but when the first haem binds to oxygen, the structure of the polypeptides change to make the haemoglobin have a high affinity for oxygen.
    - A haemoglobin with a high affinity for oxygen takes up oxygen more easily, but released it more readily. (e.g. in the lungs)
    - when one oxygen molecule is released from the haem group, it changes the shape of the haemoglobin structure, and makes it easier for the other 3 to be released, giving it a low affinity for oxygen
    - a low affinity for oxygen means the haemoglobin takes oxygen up less easily but released it more readily easily (e.g. in a quickly respiring muscle)

    Thanks in advance
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    Thanks
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    (Original post by Limitless)
    I don't know if you are just chatting ****. I never sat the exam so I don't know, I would need to ask somebody who sat the exam and does not talk out of his ass like you.
    I took the unit 4 exam in January and there was nothing on there that we hadnt done
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    (Original post by SurfingGirl)
    I took the unit 4 exam in January and there was nothing on there that we hadnt done
    I think he was trying to make everybody revise the wrong thing so everybody gets **** marks and the grade boundaries are lower and he has a chance of getting a decent grade. This is just a theory I would need to test this experiment out and repeat it several times to make it reliable and to reduce the affect of anomalous results. :cool:
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    Can someone please explain 5dii on Biology June 2010 paper??
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    (Original post by xkate1019x)
    Haemoglobin

    Are my Facts correct? I'm a bit unsure on my termonology...

    - Haemoglobin is a protein
    - It is made up of 4 polypeptide chains (quartenary structure)
    - Each polypeptide has a haem group (non protein ), which contains iron
    - It is hard for oxygen to bind with haemoglobin but when the first haem binds to oxygen, the structure of the polypeptides change to make the haemoglobin have a high affinity for oxygen.
    - A haemoglobin with a high affinity for oxygen takes up oxygen more easily, but released it more readily. (e.g. in the lungs)
    - when one oxygen molecule is released from the haem group, it changes the shape of the haemoglobin structure, and makes it easier for the other 3 to be released, giving it a low affinity for oxygen
    - a low affinity for oxygen means the haemoglobin takes oxygen up less easily but released it more readily easily (e.g. in a quickly respiring muscle)

    Thanks in advance
    Im pretty sure a high affinity for O2 means that its does NOT release it easily.
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    Can anyone explain how to work out magnification and actual size? i cant remember how to do it
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    (Original post by asim1993)
    Can anyone explain how to work out magnification and actual size? i cant remember how to do it
    Magnification = actual/ object.
    actual = magnification X object.

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    Any predictions on what may come up people?
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    (Original post by xkate1019x)
    Haemoglobin

    Are my Facts correct? I'm a bit unsure on my termonology...

    - Haemoglobin is a protein
    - It is made up of 4 polypeptide chains (quartenary structure)
    - Each polypeptide has a haem group (non protein ), which contains iron
    - It is hard for oxygen to bind with haemoglobin but when the first haem binds to oxygen, the structure of the polypeptides change to make the haemoglobin have a high affinity for oxygen.
    - A haemoglobin with a high affinity for oxygen takes up oxygen more easily, but released it more readily. (e.g. in the lungs)
    - when one oxygen molecule is released from the haem group, it changes the shape of the haemoglobin structure, and makes it easier for the other 3 to be released, giving it a low affinity for oxygen
    - a low affinity for oxygen means the haemoglobin takes oxygen up less easily but released it more readily easily (e.g. in a quickly respiring muscle)

    Thanks in advance
    all good except when haemoglobin is at the lungs its has a high affinity for oxygen thus it asscoiates with o2 more readily yet dissociates less readily. Note that its the presence of co2 at the muscles that lowers Hb affinity for oxygen.
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    lower affinity for oxygen means that when it unloads it, it unloads it easier. am i correct ??
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    Are these true and if so, is it part of what we need to know?

    "When the first haem binds to oxygen, the structure of the polypeptides changes to make the haemoglobin have a high affinity for oxygen."

    "When one oxygen molecule is released from the haem group, it changes the shape of the haemoglobin structure, and makes it easier for the other 3 to be released, giving it a low affinity for oxygen."
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    (Original post by James A)
    lower affinity for oxygen means that when it unloads it, it unloads it easier. am i correct ??
    Yea you are correct.
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    How's everyone revising for this exam? because I'm struggling juggling my subjects.
    I have an exam the day before Biol2 and two exams in the morning before Biol2... kill me now
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    (Original post by SugarLips.)
    How's everyone revising for this exam? because I'm struggling juggling my subjects.
    I have an exam the day before Biol2 and two exams in the morning before Biol2... kill me now
    unlucky you, i got maths in the morning and biol2 in the afternoon, but your timetable is deadly, what subjects you doing ??
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    (Original post by SugarLips.)
    How's everyone revising for this exam? because I'm struggling juggling my subjects.
    I have an exam the day before Biol2 and two exams in the morning before Biol2... kill me now
    I got...Chem1 tomorrow, then day off, then general studies paper teehee), then on thurs afternoon biol2 and then friday I got economics unit 2 and chemistry unit 2! And it's my leavers day!
 
 
 
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