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    I just can't motivate myself to revise for this, if id had like a week to revise it i could probs do well, but 1 day is another matter....
    off subject.... does anyone know if the synoptic part of unit 5 is actually worth half of the marks for the paper? or is it a smaller section, with more marks coming from the core unit 5? also, is the unit 4 option half of the marks for the unit 4 paper?
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    the unit 5 synoptic is worth 60% of the paper
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    (Original post by meawinner1)
    the unit 5 synoptic is worth 60% of the paper
    are you sure?that seems a hell of alot!!
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    Well it'd make sense... 4 synoptic questions vs 3 unit 5 questions... That's about 57%
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    (Original post by Bekaboo)
    Well it'd make sense... 4 synoptic questions vs 3 unit 5 questions... That's about 57%
    oh god! am not lookinh forward to that!!
    can anyone enlighten me on this:
    -the six main stages of gene technology-
    i swear the nelson book doesn't go into that much depth on gene technology, has everyone else been taught about every single stage? or is my teacher being too picky?
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    At least you guys HAVE a NAS book, i've been doing this with a private tutor who doesn't have the nas books, and you can't buy them anymore. So much of the unit five genetics isn't in the other text books and I can't find anywhere to learn it from.. I'm so screwed.. is there anyone that could help me with the last page of the unit five syllabus? I can hardly find any of it in books..
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    I know this information is a bit (ok very) late coming but you can buy them online http://www.nelsonthornes.com/stoic/p...uct_id=0012829
    I had to get my Unit 4 textbook from here because I initially taught myself it for January and they didn't give me one!
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    can someone help clear this up please

    in light dependent stage specifically non-cyclic photophosporylation
    i thought electrons in PSII are excited first and then pass to PSI to again become excited but in the nas book and it says light cause 2 electrons in both photosystems to become higher energy electrons at the same time so in p700 and p680
    why does every1 say psII is before psI if this is the case

    what should i go by?

    thanks in advanced
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    Your book explains it strangely
    Just stick with PSII to PSI and on again
    It's what the markschemes say
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    I have q's! They might not be unit 5 but whatever!

    I know vit C in nescessary for collagen synthesis, but can anyone give me a more detailed explanation as to why?

    And how is ammonia produced?
    And how is CO2 (which is used in the formation of urea) produced?
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    Ammonia is produced by deanimation. The body does not want to waste the useful energy in excess amino acids so it removes the nitrogen and a hydrogen. These combine to make ammonia, which is quickly converted to urea.

    I think the CO2 is from respiration.

    xx
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    (Original post by rachael1812x)
    Ammonia is produced by deanimation. The body does not want to waste the useful energy in excess amino acids so it removes the nitrogen and a hydrogen. These combine to make ammonia, which is quickly converted to urea.

    I think the CO2 is from respiration.

    xx
    Thanks
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    Wo wo wo i thought deamination was the process by which ammonia was converted to urea?!
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    I thought deamination was the removal of the NH2 part of an amino acid :confused: Then that combined with CO2 to form urea. I dunno, I'm so confused!!
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    (Original post by Bekaboo)
    Wo wo wo i thought deamination was the process by which ammonia was converted to urea?!
    Isn't that transamination? Oh dear.
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    Yeah thats right ramaya sorry but an extra hydrogen is taken as well. Deamination is thw whole thing from removal to the urea being produced.
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    Why can sterilised milk be stored longer than pasteurised milk?
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    Is there an essay question in unit 5????? or is it just unit 6??
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    (Original post by Ellie4)
    Why can sterilised milk be stored longer than pasteurised milk?
    Pasteurisation- short term
    Milk is flash pasteurised by heating it to 72°C for about 15 seconds. Most of the bacteria present are killed, including the pathogens. However some bacteria such as lactobacilli survive and can cause spoilage eventually. Bacterial spores also survive pasteurisation. Doesnt alter the flavour

    Sterilisation- Long term
    Milk is sterilised by heating it to 105°C for 15 seconds. This process kills all the microbes. This alters the flavour, nutrients are lost.

    Hope that answers it!
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    (Original post by Ramaya)
    I thought deamination was the removal of the NH2 part of an amino acid :confused: Then that combined with CO2 to form urea. I dunno, I'm so confused!!
    ornithine cycle:

    toxic part of an amino acid is not broken down... is the amine group (-NH2)

    deaminated in the liver

    think this means that the -NH2 group (amine group) turns into an ammonia

    make sense as deaminating = removal of the amine group (the amino group in biology) from an amino acid

    CO2 is either produced or added to the ammonia as it is converted to urea (which is it someone?)
 
 
 
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