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    What marks have you all been getting on past papers? My marks have been very varied and I'm slightly worried because my unit 2 and unit 4 past papers marks were a lot higher. I think I'm just going to go over the past papers I've done tonight and make sure I'm not making the same mistakes. Anyone else feel the same?
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    (Original post by charlottei)
    Are all three both conduction AND convection? :/
    If it makes it easier for you, always write convection because humans aren't exactly metallic
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    (Original post by sodaman96)
    In terms of homoeostasis, what does the spec mean when it says internal conditions are controlled within certain limits?
    basically negative feedback, it can deal with variations around set points but not too far.
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    (Original post by Monkey D. Luffy)
    We may have seen similar questions. The one I saw had radiation specifically on the mark scheme. There was no sign of conduction/radiation.
    Really ? hmm I've seen a few contradicting things. It's probably relevant for that question
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    (Original post by kiwi8397)
    is anyone able to explain to me the movement of an action potential in an unmyelinated axon? the textbook (pg 169) is ridiculously confusing
    Basically moves along like a mexican wave, where the Na+ions move in causing depolarisation then this causes more sodium gates to open further ahead and then resting potential reforms behind by reploarising with sodium potassium pumps.
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    Do we need to know about a generator potential because technically just before every action potential occurs there is a generator potential but this isn't usually mentioned in questions or answers. It is only discussed in the pacinian corpuscle chapter!
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    (Original post by Meganl97)
    Does anyone know of any essays that commonly come up or any topics that are crucial for essays?
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    basically what my teacher sent me
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    (Original post by JulietR)
    Guess it just means that the body can cope with slight changes in temperature etc but not with extremes
    for example if it was too cold, you would freeze to death
    (Original post by halcyon3)
    basically negative feedback, it can deal with variations around set points but not too far.


    Thanks guys, makes sense now
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    (Original post by Monkey D. Luffy)
    You could mention radiation as I have seen it in a couple of questions I have done.

    So for heat loss: Vasodilation of the arteriole walls would lead to more radiation of heat and so there will be more heat lost from the blood.
    (Original post by Vengefulcandy)
    Don't say radiation, it said accept conduction/convection in the mark scheme but reject radiation. Don't know why but its aqa biology for you
    Yeah that makes sense to me. I think the question when radiation wasn't accepted might have been the heat suit one (idk if you've done it)... but as you said that's AQA for you!

    Thanks for your help, both of you.
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    (Original post by charlottei)
    Yeah that makes sense to me. I think the question when radiation wasn't accepted might have been the heat suit one (idk if you've done it)... but as you said that's AQA for you!

    Thanks for your help, both of you.
    Thats the one, just be careful to read the stem of the question
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    Has anyone got a sample essay / essay plan on PROTEINS?
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    (Original post by triplet3)
    Good point - also would it be relevant to talk about ions in terms of being part of structures e.g proteins/carbohydrates??
    Yeah i suppose you could, but tbh I would just focus on getting the main points in first to guarantee the easy marks, then if you have time go into that. Another point you could mention briefly for unit two is the at of mineral ions into the root and xylem lowering wp, osmosis.. etc
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    (Original post by halcyon3)
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    basically what my teacher sent me
    Thanks!
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    Ok so slowly realising that I am f***ed for this exam. I feel like I might as well give up now, I know NOTHING and NOTHING is going in to my puny little brain
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    Gonna fail this exam ^^>
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    (Original post by lucyloops1996)
    Ok so slowly realising that I am f***ed for this exam. I feel like I might as well give up now, I know NOTHING and NOTHING is going in to my puny little brain
    exactly how I'm feeling rn
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    (Original post by werdo1997)
    (I'm going to assume you know how an AP starts)

    So after an AP occurs, the local depolarisation is detected by other voltage-gated ion channels further along the axon. So more Na+ ions diffuse in further along and another depolarisation occurs, so another AP. An AP will always move along the neurone and never backwards because, the previously depolarised region has entered a refractory period (ion channels closed) and becomes hyperpolarised. So only downstream ion channels can open, therefore AP can only go forward.

    In short:

    1. Other voltage-gated ion channels detect depolarisation and so open
    2. Na+ ions diffuse in and so another AP generated
    3. AP only goes forward because previous region is in refractory period
    thank you so so much dear
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    (Original post by jessiebon)
    What marks have you all been getting on past papers? My marks have been very varied and I'm slightly worried because my unit 2 and unit 4 past papers marks were a lot higher. I think I'm just going to go over the past papers I've done tonight and make sure I'm not making the same mistakes. Anyone else feel the same?
    Generally 40 on each paper without the essay. However, June 2013 was a pain, I failed that one.
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    And my college wont let me resit the year due to new policy from the government, no funding
    I am so ****ed up in this exam, I have only one essay so far.
    What the hell
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    (Original post by Ninainnarnia)
    Membranes and functions
    Relationships and interactions between organisms
    Importance of shapes fitting together in cells and organisms
    Effects of bacteria on the lives of humans and other organisms
    DNA in science and technology
    Causes of disease in humans
    Biological cycles
    Ions and organisms
    DNA and transfer of information
    did some plans for all of these and wondered if people could add to them?
    Membranes: phospholipid bilayer, mitochondrial membranes, cell surface membranes
    Relationships: energy transfer, nitrogen cycle, carbon cycle, digestion
    Shapes: enzymes-lock and key, induced fit, inhibitors, digestion, dna
    Bacteria: TB, lactose intolerance, cholera, vaccines, nitrogen cycle
    DNA tech: in vivo, in vitro, hybridisation, cancer treament?
    Causes: heart disease+lifestyle, lung disease+lifestyle, genes, bacteria/cholera
    Cycles: cardiac, heart coordination, lungs, nitrogen, carbon, nutrient/energy, cell cycle, krebs, calvin, muscle contraction
    Ions: root pressure, muscle contaction, synapses, restiong potential, action potential, nitrogen cycle, cholera
    DNA transfer: structure, semi conservative, mitosis, meiosis, transcription, translation

    need a few more ideas for some of the earlier ones, also, anyone got any more essays?
 
 
 
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