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

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    Can someone help me with this?

    One of my biology books say that "high blood pressure is detected by baroreceptors, then impulses are sent to the medulla oblongata, sending impulses along parasympathetic newurons, which secrete acetylecholine, which then binds to receptors on the SAN"

    Whereas my other biology book says that " high blood pressure is detected by baroreceptors, then impulses are sent to the center in the medulla oblongata that decreases heart rate, which then increases the frequency of impulses to the SAN via the parasympathetic nervous system"

    What should I say in my exam then?? :/
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    (Original post by mariiahgac)
    Can someone help me with this?

    One of my biology books say that "high blood pressure is detected by baroreceptors, then impulses are sent to the medulla oblongata, sending impulses along parasympathetic newurons, which secrete acetylecholine, which then binds to receptors on the SAN"

    Whereas my other biology book says that " high blood pressure is detected by baroreceptors, then impulses are sent to the center in the medulla oblongata that decreases heart rate, which then increases the frequency of impulses to the SAN via the parasympathetic nervous system"

    What should I say in my exam then?? :/

    surely the frequency of impulses to the SAN would decrease if the blood pressure is too high?
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    (Original post by angel1992)
    hey in genetic fingerprinting is all the dna cut up into fragments?
    the dna is cut near core sequences but not in the middle of core sequences, as the length of core sequences is important in genetic finger printing too.
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    (Original post by percy93)
    all i know is pcr replicates smaller amounts than in vivo, which has the ability to replicate large amounts of DNA
    But why...what do you think?
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    (Original post by flowerscat)
    Embryonic stem cells (at the 16 cell stage) are totipotent - each cells is capable of regenerating to all the cells in the body, including the umbilical cord (and therefore a new foetus)

    Once they become pluripotent, they can only differentiate into one of the 3 tissue types - digestive organs, skeletal system or nervous system. They cannot develop into umbilical tissue, hence incapable of forming a new foetus.

    Adult stem cells are multipotent, hence not as powerful as embryonic stem cells

    Here is a website which explains this quiet well:

    http://biomed.brown.edu/Courses/BI10...ersatility.htm
    The cells used in research are pluripotent - you take them from the inner mass of the blastocyst - hence you destroy the embryo.

    Embryonic stem cells are pluripotent - not totipotent.

    http://en.wikipedia.org/wiki/Embryonic_stem_cellm
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    Specimen paper Q5ai) The mark scheme says:

    "Sodium ions move out of axon;
    By diffusion/down concentration gradient;
    Through sodium ion channels/sodium ion channels open;"

    This this a typo? Or have I had it the wrong way round the whole time??
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    (Original post by percy93)
    hahahahahahhahhhahha... that always gets me
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    (Original post by IFondledAGibbon)
    Specimen paper Q5ai) The mark scheme says:

    "Sodium ions move out of axon;
    By diffusion/down concentration gradient;
    Through sodium ion channels/sodium ion channels open;"

    This this a typo? Or have I had it the wrong way round the whole time??
    This confused me today too. It's a mistake definitely.
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    (Original post by IFondledAGibbon)
    Specimen paper Q5ai) The mark scheme says:

    "Sodium ions move out of axon;
    By diffusion/down concentration gradient;
    Through sodium ion channels/sodium ion channels open;"

    This this a typo? Or have I had it the wrong way round the whole time??
    Typo! Have a liitle faith in yourself!
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    [QUOTE=vickidougal;32333852]
    (Original post by flowerscat)

    thank you very much is adrenaline an enzyme then? i thought it was a hormone?

    You are right it is a hormone - just one capable of activating an enzyme cascade in the cell which results in release of glucose.
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    (Original post by LeBubbled)
    This confused me today too. It's a mistake definitely.
    (Original post by Destroyviruses)
    Typo! Have a liitle faith in yourself!
    Good news! I can't believe they would make such a fundamental mistake. Dip****s.
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    (Original post by flowerscat)


    Its a neurotransmitter - neither a hormone nor an enzyme
    Actually it is both a neurotransmitter and a hormone
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    (Original post by Cyanohydrin)
    The cells used in research are pluripotent - you take them from the inner mass of the blastocyst - hence you destroy the embryo.

    Embryonic stem cells are pluripotent - not totipotent.

    http://en.wikipedia.org/wiki/Embryonic_stem_cellm
    The cells used in research are pluripotent - research on totipotent cells is not allowed in the UK (hence neither is germ-line therapy). However the term "embryonic stem cells" can be applied to the early zygote as well.
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    (Original post by Cyanohydrin)
    Actually it is both a neurotransmitter and a hormone
    Typo on my part - I did go and correct my post
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    (Original post by vickidougal)
    how come adrenaline forms a substrate receptor complex with the receptor on the CSM then? i thought that only applied to enzymes when their active site binds to a substrate

    Nooooo - it applies to any molecule that can fit into its receptor. Eg. antibody binding with a specific antigen (where the antigen need not be a protein)
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    (Original post by Cyanohydrin)
    Actually it is both a neurotransmitter and a hormone
    What is?
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    help hahaha

    Can someone help me with this?

    One of my biology books say that "high blood pressure is detected by baroreceptors, then impulses are sent to the medulla oblongata, sending impulses along parasympathetic newurons, which secrete acetylecholine, which then binds to receptors on the SAN"

    Whereas my other biology book says that " high blood pressure is detected by baroreceptors, then impulses are sent to the center in the medulla oblongata that decreases heart rate, which then increases the frequency of impulses to the SAN via the parasympathetic nervous system"

    What should I say in my exam then?? :/
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    (Original post by Jasmine_009)
    Question!!!
    Some organisms are adapted for living in hot, dry environments.
    Explain what causes the activity of reptiles living in a desert to vary greatly over a twenty-four hour period.

    If they are ectotherms, then they would have move from cold to warm in the day time and hot to shade in the mid-afternoon, then under a warm sheltered spot in the night?
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    (Original post by Destroyviruses)
    What is?
    Adrenalin.

    I was wondering. If we are asked about the initial cause of the depolarising stiumulus that causes the voltage gated sodium channels to open ....and then an action potential....

    what would you say?

    'they are the result of the receptor to the stiumulus - for example some chemicals trigger chemoreceptors to open chemical gated sodium channels, likewise pressure gated receptors (i.e. pacinian corpsucle) etc etc ...?'
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    (Original post by angel1992)
    im really confused about pcr use in genetic fingerprinting, NT text book says it amplifies th edna sample and then uses restriction endonucleases to break the sample up, so in pcr how big is the sample that is amplified? how do they choose it? and if it just a section of dna, in parent fingerprinting wont you need two dna sections, one from each chromosome?

    Its really hard trying to amplify the whole human genome.

    Instead primers are used which amplify short-tandem repeat regions (STRs).

    STRs are 4-5 bp sequences which are common to all human DNA.

    They are located in the intron regions.

    However, the number of times that they repeat is unique in each individual.

    Therefore = amplify regions of STRs by PCR = run on a gel = look at pattern of STR bands for a match.

    Which page on the NT book says that restriction enzymes are used in genetic fingerprinting?
 
 
 
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