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AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011 watch

  • View Poll Results: Are you resitting this unit?
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    (Original post by kingsmod1)
    guys, i think im gonna get BBB at A level wid bio chem and maths (strted wid DDD)

    i have always wanted an A and i feel these grades are terrible at A level just for myself

    do u lot think its that bad

    p.s. bio 5 is makin gd progress :P
    BBB is good. Especially since you started at DDD.
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    (Original post by tehsponge)
    I thought they had to be as detailed as the 6 mark questions you get at the end of the unit 4 paper? I've always thought of them as like 3/4 of those questions. Also I can't remember much from unit 2 because I found it so mind numbingly boring.
    You won't need to know the content to the sort of detail for each individual unit. Remember scientific content is only 16 marks, breadth, relevance and quality of written communication makes up the other 9 marks, and most people drop the marks on the these things
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    (Original post by tehsponge)
    BBB is good. Especially since you started at DDD.
    but it just feels bad that u kno i could of got A especially in maths coz of stupid mistakes!

    feels bad that wen i think bk in the past got bs wen im capable of more lol
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    (Original post by choc1234)
    howmuch synoptic revision has everyone done?
    has everyone learnt everything from AS in detail?
    bit worried
    Basically none as of yet. Going to have a go at planning most of the essay titles and see what things I could have included that I didn't but I doubt I'll be doing many practice essays themselves or much else, need all the time I can get to make sure I know Biol5 content well enough.

    What is everyone else doing for the essay preperation?
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    'Explain why ‘base-pairs’ is a suitable unit for measuring the length of a piece of DNA.'

    Anyone able to help? I have a general idea but not entirely sure.
    Is it that base pairs are all the same length and DNA is made up of 2 bases paired together?
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    (Original post by AboutAn8orA9)
    'Explain why ‘base-pairs’ is a suitable unit for measuring the length of a piece of DNA.'

    Anyone able to help? I have a general idea but not entirely sure.
    Is it that base pairs are all the same length and DNA is made up of 2 bases paired together?
    the length between each base pair and the next base pair is constant
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    Can anyone explain 'transforming' specifically the antibiotic resistance markers section.

    The book is really confusing me

    Thanks
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    hey can anyone explain why in homeostasis the set level is never perfectly maintained, i dont get its, i get out fluctuations occur an negative feedback brings them back to set level but i dont get why this set level isnt maintained and oscillations still occur?
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    Does anybody know what two questions are gonna be on topic wise?...exams on wednesday
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    (Original post by angel1992)
    hey can anyone explain why in homeostasis the set level is never perfectly maintained, i dont get its, i get out fluctuations occur an negative feedback brings them back to set level but i dont get why this set level isnt maintained and oscillations still occur?
    because were constantly moving into different environments, like going outside when its colder, so your body temperature goes down and then goes back up when vasoconstriction occurs and shivering etc..

    or eating, so blood glucose levels fluctuate etc..
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    (Original post by cws121)
    because were constantly moving into different environments, like going outside when its colder, so your body temperature goes down and then goes back up when vasoconstriction occurs and shivering etc..

    or eating, so blood glucose levels fluctuate etc..
    hey yh i get that, but i read somewhere that is says even when temperature is more or less constant oscillation occurs to prevent both corrective mechanisms from operating at once, but i dont get that
    heres where i read it from

    http://www.biologymad.com/resources/...omeostasis.pdf type keyword oscillates in the pdf word search for the paragraph im on about
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    Can someone please tell me whether the old Bio A or B is more similar to our spec? Which one do you suggest to do the past papers from? Or both? Thanks
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    Hi all, I just came across a past paper question which has completely stumped me, and I was wondering if anyone has any ideas as to what the answer might be? (I can't look it up because its from an ancient paper, but it is still relevant)

    Anyway, at the beginning of the question it gives some information about arrow poisons and curare ... "The experiment showed that the injection of arrow poison into the blood stream causes death by respiratory failure. It is now known that curare competes with acetylcholine molecules for receptors at neuromuscular junctions. Since Watertons work, many other chemicals have been discovered which also affect the nervous system, two of which are anatoxin and saxotoxin. Anatoxin also affects synpases. Its molecules are very similar to those of acetylcholine but they are not broken down by acetylcholinesterase."

    Then the question is: "suggest an explanation for the fact that one of the symptoms of anatoxin poisoning is the excessive production of tears"?

    I have sat and tried to work it out, but I can't! All I have deduced is that it will lead to action potentials being constantly fired, and I though that in an attempt to get rid of some of the sodium ions the body might try and get them out with tears? (because sodium is in salt, which is in tears) But this doesn't seem like a likely answer, does anyone have any other ideas?
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    hey, do ectotherms have homeostasis, as homeostasis is the regulation of a constant internal environemnt its just endotherms and ecttherms do this diffrent ways
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    (Original post by Flux_Pav)
    thanks
    and also for the latter, inserting two healthy recessive genes will only work by gene replacement rather than supplementation right? because recessive alleles cannot mask the effects of the dominant alleles
    Also...
    If its caused by a dominant gene then a piece of DNA can be put between the allele to stop it working...then a healthy working allele can be inserted

    Thats what it say in the CGP guide...

    Hope i helped!
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    (Original post by sd2011)
    could someone help on what to include in these essays please the biological importance of water and the importance of hydrogen bonds in living organisms? (i think proteins structure and DNA anything else) ?
    there are H bonds in between cellulose chains to form the microfibrils.
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    Why do prokaryotic cells not splice pre mrna?
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    (Original post by cws121)
    Why do prokaryotic cells not splice pre mrna?
    Most prokaryotes don't have introns
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    Hey!

    Right, so I know aerobic resp. requires o2 but where specifically in the krebs cycle is o2 used?

    Glycolysis & Link reaction - don't need o2
    Krebs?
    ETC - as the final acceptor

    Thank you!
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    I think one the essays will be protein related...or maybe i'm just wishful thinking hmmm!!!
 
 
 
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