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    (Original post by tsr1)
    how does lactate makes NAD available? can someone explain please? thanks
    It oxidises the NADH2 by taking the H from it - so reducing pyruvate to lactate. This is necessary so that the NAD can go back and do glycolosis again with the next glucose molecule.
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    (Original post by Mjwilson1988)
    Here is a post I did earlier about the whole GMOs producing drugs etc.



    As for the Human Genome Project, this was a massive undertaking to map the entire genome (every gene) found in human DNA. Using data from this project can help with identifying which genes can cause certain diseases, which alleles give greater risk of certain cancers, it can help with personalising drugs as each persons genetic make up can have something to do with the way their body reacts with particular drugs (side effects and dosage etc) so knowing the genome of a person can help tailor a drug specific to that person. Also, by identifying all the genes we can make drugs which will specifically act as transcription factors for those genes, allowing better gene expression (or suppression etc).
    Thanks a billion!
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    Which questions in this article do YOU think is likely to come up?
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    (Original post by Sly1)
    How would you guys answer the core practical question on how to investigate the effects of exercise on tidal volume and breathing rate?
    Using a spirometer, calibrated to correctly for volume. Get a group of people all of the same ethnic background or age (This is to control more variables to make the results more reliable and conclusion more valid), and get an average for each person of all their resting tidal volumes and breathing rates, Tidal volume is measured as the amplitude of a single wave on the spirometer trace, which is the distance between the highest point and lowest point, and breathing rate is how many of those waves occur in one minute.

    Then put them on a treadmill and do it again (you could also just get them to stand at rest whilst using the spirometer and then get them to run on the treadmill so you can see the effects on one single trace.) Make sure each person is running at the same speed (more variable controlled). The differences in the spirometer traces are possibly because of the exercising. Take another average of tidal volume and breathing rate. Repeat with many people of different ages and backgrounds to test for differences there too.
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    (Original post by Mjwilson1988)
    Using a spirometer, calibrated to correctly for volume. Get a group of people all of the same ethnic background or age (This is to control more variables to make the results more reliable and conclusion more valid), and get an average for each person of all their resting tidal volumes and breathing rates, Tidal volume is measured as the amplitude of a single wave on the spirometer trace, which is the distance between the highest point and lowest point, and breathing rate is how many of those waves occur in one minute.

    Then put them on a treadmill and do it again (you could also just get them to stand at rest whilst using the spirometer and then get them to run on the treadmill so you can see the effects on one single trace.) Make sure each person is running at the same speed (more variable controlled). The differences in the spirometer traces are possibly because of the exercising. Take another average of tidal volume and breathing rate. Repeat with many people of different ages and backgrounds to test for differences there too.
    Cool guy cheers man hope u get A* and me ofc
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    can someone please explain the answer to Jan 2011 question 5c (i) and (ii)?? i dont get the stupid markscheme
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    (Original post by I Hate Edexcel)
    Noone replied. I asked why the cells that were altered to contain cancer-causing genes were inserted into mice that had their immune systems compromised.
    So the mice don't reject the new cells and kill them with their functioning immune system.
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    and also explain the answer to june 2010, question 4c with the ECG! thanks!
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    Could someone please give core practical details to this:
    Describe how to investigate habituation to a stimulus
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    (Original post by Mjwilson1988)
    I probably should use Embryo though, it is the more scientific word. I don't know why I didn't at the time, sometimes in practice questions I write pretty decent stuff and then look at the mark scheme and realise that they give loads of marks if you just use the most scientific terminology possible. Hah, you should see my past papers, I think on every one I've written "Use more technical language!"
    Well - it is not so much about tecnical language as about what the cells do. A fertilised egg / embryo is pluripotent at the stage they do this at (at about 8 cells say). So when they put in the new gene and insert it, it can go ahead and differentiate and become a viable organism. The unfertilised egg is just a gamete that cannot do any of that stuff. Sorry to be picky - but I don't want anyone to mess up in the exam by saying that a GM egg gets inserted into the animal and loose marks. I guess understanding why it is the embryo that is used, rather than any other cell helps me get my head round it. It is the very fact of the pluripotency of very early embryo cells that makes GM in animals possible....

    This also helps with an ethics point - in human embryo research and GM stuff they are potential people - even if they were IVF excess and were going to be chucked out...

    Hope that helps. Don't want to get on anyone's nerves! Sorry also for some repetition - I was answering Qs as I read through the thread - before realising others had answered.

    Good luck tomorrow everyone!
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    Is this exam usually tight for time? Does anyone know? Do you have to rush to get through it?
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    (Original post by I Hate Edexcel)
    Is this exam usually tight for time? Does anyone know? Do you have to rush to get through it?
    Last time I wasn't able to finish it- couldn't attempt 5 marks or so. But that's because I didn't read the pre-release booklet completely before sitting the exam, so had to keep trawling through the pages.

    I also got bogged down quite a bit in some of the earlier questions.
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    (Original post by Tomatochuckers)
    Last time I wasn't able to finish it- couldn't attempt 5 marks or so. But that's because I didn't read the pre-release booklet completely before sitting the exam, so had to keep trawling through the pages.

    I also got bogged down quite a bit in some of the earlier questions.
    Ok, thanks! I'll try and be brisk then. Were the questions on the pre-release difficult? And were they general or very specific to the booklet? I'm kind of scared because I don't know what to expect.
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    I've tried searching the thread but can't find a link to the annotated article, can somebody help (my previous link to it no longer works :/)


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    I know I'm going to fail this. I've done crap in unit 4 and will do more crap tomorrow. Life sucks
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    (Original post by EstebanK0)
    I know I'm going to fail this. I've done crap in unit 4 and will do more crap tomorrow. Life sucks
    Dedication hard work dedication hard work
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    the differences between depolarisation, repolarisation and hyperpolarisation and action potential?
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    (Original post by Sly1)
    Dedication hard work dedication hard work
    It's too late though. There's like 14.5 hours left 'till the exam and there's so much I don't know. I just suck at bloody education.
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    In how much detail do we need to learn the link reaction and the Krebs cycle?

    The CGP book has it in much greater detail than the SNAB textbook does.

    i.e. is this enough knowledge:

    Glycolysis: Glycogen in liver converted to glucose. Phosphate added from two ATP which makes glucose more reactive. This then breaks into down two 3 carbom molecules. These are oxidised to form two molecules of pyruvate. 2 NAD take a hydrogen atom each so we then get 2 reduced NAD

    Link reaction: Pyruvate is dehydrogenated and decarboxylated forming a 2 carbon compound (acetate). This then joins with coenzyme A to get acetyl coenzyme A. Carbon dioxide is released as a waste product, and coenzyme NAD takes up the 2 hydrogens


    Krebs Cycle:
    In the Krebs cycle, each two carbon molecule of acetyl coA entering the cycle results in the production of two carbon dioxide molecules, one molecule of ATP by substrate level phosphorylation, and 4 pairs of hydrogen atoms which are mainly taken up by NAD with those being released in one particular step of the Krebs cycle being taken up by FAD.

    Then I'd go on to explain the ETC and chemiosmosis

    Is this enough detail?
    Thanks!
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    (Original post by EstebanK0)
    It's too late though. There's like 14.5 hours left 'till the exam and there's so much I don't know. I just suck at bloody education.
    If I was in your position I would get the spec and read the fat snab book 5 times before the exam.
 
 
 
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