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    grade boundary predictions?
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    (Original post by talkbiology)
    How? Just because the primer used was shorter doesn't mean the whole allele was shorter (does it? idk halp)
    I really don't know, I've confused myself now
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    Seems like everyone on TSR went for essay B? I thought essay A seemed easier tbh.
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    My grade predictions since it was easier that Jun'14

    A* - 69
    A - 64
    B - 58
    C - 54
    D - 50
    E - 46
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    Hi. For the damage to myelin sheath could you put that this will cause more action potentials forming leading to involuntary muscle contraction as the myelin sheath prevents action potentials forming?
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    (Original post by Algebraicly)
    Hi. For the damage to myelin sheath could you put that this will cause more action potentials forming leading to involuntary muscle contraction as the myelin sheath prevents action potentials forming?
    I'm not sure it stops them from forming, its more about making the ones that are there travel faster, due to saltatory conduction
    The only way to increase the number of action potentials is to increase the intensity of the stimulus, which the lack of myelin does not do
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    (Original post by Algebraicly)
    Hi. For the damage to myelin sheath could you put that this will cause more action potentials forming leading to involuntary muscle contraction as the myelin sheath prevents action potentials forming?
    No idea, I put that saltatory conduction wasnt able to occur as a result and therefore the impulses had to travel as a wave affecting muscle contraction.
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    (Original post by Algebraicly)
    Hi. For the damage to myelin sheath could you put that this will cause more action potentials forming leading to involuntary muscle contraction as the myelin sheath prevents action potentials forming?
    I wrote

    No saltatory conduction ( no myelin sheath) so depolarisation occurs at every point along the nerve. Therefore action potential takes longer to reach the neuromuscular junction. Leads to delayed muscle contraction.

    I think that the answer anyway
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    (Original post by lauraedgar)
    I'm not sure it stops them from forming, its more about making the ones that are there travel faster, due to saltatory conduction
    The only way to increase the number of action potentials is to increase the intensity of the stimulus, which the lack of myelin does not do
    we got taught the myelin sheath is an electrical insulator therefore it does not allow electrical circuits be set up there so the action potential can't spread?
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    Hi! I thought the paper was ok considering my minimal revision, I did essay A for which i wrote about:

    Homeostasis principle
    Thermoreg
    Enzymes
    Blood pH -> chemoreceptors
    Baroreceptors, pressure, bio basis of heart disease
    Immune Response
    Stomata/Plants, photosynthesis, plant tropisms
    ATP formation in anae respiration
    Muscle contraction
    Natural selection/Adaptation

    Posted from TSR Mobile
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    (Original post by Rezaa)
    I wrote

    No saltatory conduction ( no myelin sheath) so depolarisation occurs at every point along the nerve. Therefore action potential takes longer to reach the neuromuscular junction. Leads to delayed muscle contraction.

    I think that the answer anyway
    if an action potential occurs everywhere then it'll be closer to the target muscle as it could be created at the end of the neurone?
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    how many points do would you usually write in an essay, I wrote detailed paragraphs on reflex arc, temp regulation and insulin regulation, is that enough?
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    (Original post by erudite)
    sorry meant essay A! not b


    Posted from TSR Mobile
    I did think those points didn't have anything to do with essay B haha
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    (Original post by Algebraicly)
    we got taught the myelin sheath is an electrical insulator therefore it does not allow electrical circuits be set up there so the action potential can't spread?
    Yeah i was thinking that the myelin sheath being an insulator has some role to play but i didn't revise properly so i didn't risk making something up and stuck with saltatory conduction

    In the question it said MS sufferers have jerky and slow muscle contraction so i think, the insulating explanation is used to justify the jerking and saltatory conduction to explain the slow response

    And as someone earlier mentioned, i think, it said suggest one reason so both would have been creditworthy

    it's all good! I hope
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    (Original post by Algebraicly)
    if an action potential occurs everywhere then it'll be closer to the target muscle as it could be created at the end of the neurone?
    eh?
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    (Original post by Badru77)
    I am laughing so hard I can't contain myself xDDDDDD

    You'll get a few marks for laughter ....
    Hahaha that's excellent, I was laughing to myself in the exam when I had to write testes, so mature 😂
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    (Original post by erudite)
    sorry meant essay A! not b


    Posted from TSR Mobile
    Essay a i think people thought was easier because it was straightforward and for b they listed a load of things people probably couldn't be bothered with it

    plus, internal and external environments is all the stuff that gets drilled into our head much earlier on in AS, people pay less attention to things like growth and reproduction etc

    idk thats just me
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    (Original post by ImNotReallyMe)
    Yeah i was thinking that the myelin sheath being an insulator has some role to play but i didn't revise properly so i didn't risk making something up and stuck with saltatory conduction

    In the question it said MS sufferers have jerky and slow muscle contraction so i think, the insulating explanation is used to justify the jerking and saltatory conduction to explain the slow response

    And as someone earlier mentioned, i think, it said suggest one reason so both would have been creditworthy

    it's all good! I hope

    yeah I read about jerky movements and that means abrupt stop and starts in the dictionary. So I thought it would be something to do with involuntary
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    (Original post by ImNotReallyMe)
    Essay a i think people thought was easier because it was straightforward and for b they listed a load of things people probably couldn't be bothered with it

    plus, internal and external environments is all the stuff that gets drilled into our head much earlier on in AS, people pay less attention to things like growth and reproduction etc

    idk thats just me
    Yeah I agree, even from GCSE we've been taught a lot on homeostasis and stuff, and for essay B - i looked at it n thought "wtf" like I didn't really know what it was asking tbh, but then got really into essay A and felt like I could go on for days talking about heaps and heaps of stuff!
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    They said it was hydrophilic. Its not the same thing as being lipid soluble.

    Posted from TSR Mobile
 
 
 
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