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

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    (Original post by tehsponge)
    Thats what I initially thought too, but CGP says:
    "In high humidity they (woodlice) move slowly and turn more often, so that they stay where they are. As the air gets drier, they move faster and turn less often, so that they move into a new area. This response helps woodlice move from drier air to more humid air. (to reduce water loss)"

    I have no idea which definition to go with now
    Yeah i remember getting a bit confused reading CGP too, just ignore it. I asked my teacher and she said that that wasn't the definition. If you have the Nelson Thornes text book, use the definition in there, cause it's endorsed by AQA
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    (Original post by jamest92)
    I have no thumbs, how else can i remember this ?
    If you're being serious then just imagine pressing a thumb, this would stretch the thumb like the PC and widen the sodium channels, allowing an influx of sodium ions. This depolarizes the membrane.
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    I really hope muscles come up in tomorrow's paper. They haven't come up yet!
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    (Original post by Sparkly-Star)
    I'm gonna fail in the synoptic essay. I can't remember a thing from the other units.
    me too im hoping the essay question is based on something in unit5 only
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    (Original post by booooom)
    for an essay question on the importance of negative and positive feedback, what can be included from unit 1, 2 and 4?
    please answer
    Is transpiration negative feedback?
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    Eek, exam in less than 22 hours :eek: I feel like I'm forgetting/forgotten all the stuff I learnt :/ Well I hope that the grade boundaries are low like last year, possible even lower if we're lucky
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    (Original post by NRican)
    Is transpiration negative feedback?
    im really not sure. Do you always have to include things from other units? i mean for a question like this the only things i can think about are unit 5 homeostasis and the menstruall cycle
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    (Original post by Destroyviruses)
    The recombinant DNA. Is just DNA that is made using mRNA.

    For example if you know an mRNA codes for a particular protien and you want loads of that protein. You can get a bacteria to make it for you. But you'll need it in DNA form so it can be inserted into plasmids.

    To turn the mRNA into recombinant DNA. You use a particular enzyme called reverse transcriptase (see its a nice name because its the oposite of transcription so REVERSE TRANSCRIPTASe)

    So recombinant DNA is nice when you want only a particular gene.Because they are made from mRNA and mRNA obly code for particular genes.
    Thanks. I knew that but I didn't know that it was called recombinant DNA
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    i cant think of anything for neg or poss feedback for unit1,2 or 4 i can think of homeostasis and the menstrual cycle but thats about it really
    is this essay on a past paper or is it a made up one
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    (Original post by booooom)
    im really not sure. Do you always have to include things from other units? i mean for a question like this the only things i can think about are unit 5 homeostasis and the menstruall cycle
    Well I don't think breadth just means including topics from AS and A2 but from different sections in Biology itself, eg plants, bacteria, animals and subsections within them
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    (Original post by hahaff)
    i cant think of anything for neg or poss feedback for unit1,2 or 4 i can think of homeostasis and the menstrual cycle but thats about it really
    is this essay on a past paper or is it a made up one
    its a past questio. my teacher gave me a list of past essay questions which have come up, what bout the bohr effect frm unit 2--negative feedback??
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    (Original post by hahaff)
    i cant think of anything for neg or poss feedback for unit1,2 or 4 i can think of homeostasis and the menstrual cycle but thats about it really
    is this essay on a past paper or is it a made up one
    *Chemo receptors
    *Pressure receptors
    *Influx of sodium ions
    *Temperature
    *Blood glucose conc.
    *Menstrual cycle

    I don't know about the other units haha! :p:
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    in DNA sequencing, do you pick out only one piece of dna and clone it by PCR ?
    or do you sequence the whole genome by cutting it into pieces ?

    and also, how do you know that the fragment that moved the furthest only consisted of one nucleotide?

    it could be any size as long as its the smallest, isn't it?
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    What topics would you write about in these essays?

    Describe how the structure of different polymers are related to their function.
    The movement of substances within living organism
    The role of the cell surface membrane in living organisms.
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    How can there only be one past paper?
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    (Original post by Flux_Pav)
    totipotent cells can mature into any body cell of the organism - they are unspecialised
    embryonic stem cells are also unspecialised and are more potent that adult stem cells
    So if you were asked to define a "stem cell" or a "totipotent cell" what would you say?

    Just read the Wiki article and it seems to me that a zygote is a totipotent cell. There are no other cells which are totipotent. When it divides and develops into an embryo, the cells are then called stem cells? Basically I have no idea what I'm talking about!
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    (Original post by Sparkly-Star)
    I really hope muscles come up in tomorrow's paper. They haven't come up yet!
    They did a bit in the 2010 paper, but not in much detail.
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    (Original post by Munster)
    How can there only be one past paper?
    I know it's stupid. First year to take it were last years year 12 and AQA only do June exams for Unit 5.
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    (Original post by sleungs)
    So if you were asked to define a "stem cell" or a "totipotent cell" what would you say?

    Just read the Wiki article and it seems to me that a zygote is a totipotent cell. There are no other cells which are totipotent. When it divides and develops into an embryo, the cells are then called stem cells? Basically I have no idea what I'm talking about!
    when they ask you to define a stem cell, they would tell you what type of stem cell - embryonic or adult
    -adult stem cells- multipotentcells that can mature into limited range of cell types. e.g those in bone marrow only produce blood cells

    -embryonic stem cells - pluripotent cells that are formed in the earliest stages of embryonic development during IVF

    totipotent cell - cell that can mature into any body cell of an organism

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    (Original post by NRican)
    What topics would you write about in these essays?

    Describe how the structure of different polymers are related to their function.
    The movement of substances within living organism
    The role of the cell surface membrane in living organisms.

    1. Unit 2: Starch, glycogen, cellulose, DNA, haemoglobin. Unit 1: Enzymes, antibodies, membrane proteins. Unit 4: Enzymes in photosynth and resp. Unit 5: Myosin/Actin Neurotransmitters/Hormones RNA.

    2. Unit 1: Diff, Osmosis, Facil Diff, Active Transport. Unit 2: Examples: Plants (uptake of water/minerals) Haemoglobin = pCO2 etc Unit 4: Chemiosis (electrochemical gradient) (resp and photo), uptake of fertiliser. Unit 5: Resting potential (Active Transport and Facil Diff) ca + and na + in muscle contraction and neurone propagation.

    3. Unit 1: Phospholipid bilayer basics: Properties, specific receptors, membrane proteins etc. Immunity: antigens on surface, identifies as foreign. Unit 2: Tissue fluid, exchange of substances. Unit 4: diffusion of CO2 into plants for photosynthesis, chemiosis. Unit 5: Neurone cell membranes, secondary messanger.
 
 
 
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