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

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    (Original post by qwerty54321)
    Can anyone explain simply how independent segregation creates variety (during meiosis)?
    I understand it fully - just really can't explain it!!
    And well done to everyone on their unit 1 scores - can't quote everyone back but hopefully we'll all be on As after this exam tmrw
    I like to think of indepedant segregation as a pack of cards much like the analogy in the book! where the chromatids randomly come together in pairs to form haploid cells. However i'm still stuck on a mark scheme acceptable answer myself. Meiosis is a pain for me to remember.
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    (Original post by TlanTlan)
    You extract serum from one organism, which contains antigens, then inject it into another organisms blood steam. This organism produces antibodies against the antigens from the first organism, then the serum from the second organism is mixed with the serum from a different organism, and a precipitate is formed. The amount of precipitate formed is directly proportional to the evolutionary relationship between the first organism and third organism.

    I like to think of the second organism as a middle man.
    its not serum, its actually semen lol JK
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    (Original post by ScienceGeek3)
    Actually tissue fluid you could long out for 6 marks, discussing why there is a high blood hydrostatic pressure at the arterial end, why it is lower at venous end, overcoming frictional resistance. The water potential gradients, the large proteins that lower the water potential gradient, the excess drainage of tissue fluid returns to the blood at the subclavian vein etc.

    Although for the record I don't think it's the 6 marker
    I can't even be bothered with that question haha

    Thanks though, i'll make sure I know it...

    I just hope it's transpiration pull tbh >.<
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    (Original post by Jorgeyy)
    I can't even be bothered with that question haha

    Thanks though, i'll make sure I know it...

    I just hope it's transpiration pull tbh >.<
    It's going to be in the exam most likely, considering the past papers all had a question about it.
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    Transpiration would be a nice 6 marker to be sure.
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    "names are required only of the coronary arteries and of blood vessels entering and leaving the heart etc"
    what are the coronary arteries names we need to know? thanks
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    (Original post by Jorgeyy)
    I can't even be bothered with that question haha

    Thanks though, i'll make sure I know it...

    I just hope it's transpiration pull tbh >.<
    Meh, I hate all things plants I'm counting on it being gas exchange in insects/fish! Unless Aqa are feeling really generous and make it something on blood vessels, but I'm doubting that higly :bawling:
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    (Original post by jessplease)
    "names are required only of the coronary arteries and of blood vessels entering and leaving the heart etc"
    what are the coronary arteries names we need to know? thanks
    I was speaking to liviaaa about this earlier, she mentioned you need to know of the vessels leaving and entering the liver and kidneys too! I believe for the liver is the hepatic vein/artery and hepatic portal vein and for the kidneys it's the renal artery/vein.. I don't even think this is mentioned in the NT book!
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    (Original post by ScienceGeek3)
    Meh, I hate all things plants I'm counting on it being gas exchange in insects/fish! Unless Aqa are feeling really generous and make it something on blood vessels, but I'm doubting that higly :bawling:
    Yeah im game for fish or insects, hopefully at least some 3 markers on those

    Yeah but the Jan 2011 paper had a 6 marker on arteries/arterioles so I doubt it

    I'm an expert on muscle layer/elastic layer and endothelium now though because of that hahaha !
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    An A is like 54 on the jan 2011 paper out of 85!! that seems low but the biology mark schemes r soo random and specific wat they put or nothing at all tbh im just gunna study the mark scheme i give up!!
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    (Original post by ScienceGeek3)
    I was speaking to liviaaa about this earlier, she mentioned you need to know of the vessels leaving and entering the liver and kidneys too! I believe for the liver is the hepatic vein/artery and hepatic portal vein and for the kidneys it's the renal artery/vein.. I don't even think this is mentioned in the NT book!
    Page 185
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    (Original post by LifeIsGood)
    Page 185
    Haha my bad, clearly haven't read the book thoroughly enough
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    (Original post by ScienceGeek3)
    I was speaking to liviaaa about this earlier, she mentioned you need to know of the vessels leaving and entering the liver and kidneys too! I believe for the liver is the hepatic vein/artery and hepatic portal vein and for the kidneys it's the renal artery/vein.. I don't even think this is mentioned in the NT book!
    yeahhhh you need to know entering and leaving heart, liver and kidneys. But before that it says names of the coronary arterys? and i haven't read about that anywhereee
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    Can anyone explain antibiotic resistance to me please? so confused :/
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    hate chapter 13.
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    (Original post by jessplease)
    yeahhhh you need to know entering and leaving heart, liver and kidneys. But before that it says names of the coronary arterys? and i haven't read about that anywhereee
    what are the coronary arteries? D:
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    6 marker on insects/fish? YES PLEASE.
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    (Original post by xkate1019x)
    Can anyone explain antibiotic resistance to me please? so confused :/
    What don't you understand? Bacteria can be resistant to certain antibiotics due to random mutations or due the plasmid containing the resistant gene being passed on to them via conjugation from one species to another species - horizontal gene transmission or from one generation down to another generation vertical gene transmission. If the bacteria possess the resistance gene then it is no longer affected by that particular antibiotic, i.e. the antibiotic will not kill the bacteria. Therefore a "cocktail" of antibiotics are usually given in treatment in the hope that atleast one type of antibiotic will be effective. The bacteria can usually produce an enzyme e.g penicillinase (excuse the spelling) which can break down penicillin before the antibiotic can cause the bacteria any harm.

    That's just from memory, some parts may be slightly off but I think those are the main points!
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    (Original post by DoaaK)
    hate chapter 13.
    Everyone does! :rolleyes:

    (Original post by HaimishaParekh)
    6 marker on insects/fish? YES PLEASE.
    What could they ask about insects? :confused:
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    (Original post by xkate1019x)
    Can anyone explain antibiotic resistance to me please? so confused :/
    resistance occurs by chance due to mutation, and if you give antibiotics to someone who has a resistant bacterium, due to natural selection these bacteria will survive and then pass on this resistant gene by either horizontal or vertical gene transmission and therefore increase the frequency of resistant allele in population
 
 
 
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