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Edexcel A2 Biology SNAB 6BI04 ~ 6BIO5 June 2016 Watch

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    (Original post by Leilahannoun1)
    Can anyone explain the idea of grazing ?
    I think it has to do with herbivores feeding on plants, I am not sure though

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    Hi guys, for unit 5 what do we need to know about acetylcholine?
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    Could someone please explain how to do the spirometer core practical. My teacher couldn't figure out how to use the machine so we didn't do it and then she made us sign the sheet saying we'd done all the core practicals.
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    (Original post by etherealinsanity)
    Could someone please explain how to do the spirometer core practical. My teacher couldn't figure out how to use the machine so we didn't do it and then she made us sign the sheet saying we'd done all the core practicals.
    http://www.snabonline.com/content/to...ts/a7_13sb.pdf
    This is the practical sheet could be useful to you if you don't already have it

    Also, you can search up a demonstration on youtube to go with prac sheet. Read prac sheet first, then look at a video.

    If you look at sheet A it has Qs on the subject to ensure you understand prac
    http://www.snabonline.com/content/to...ts/a7_13sa.pdf

    This sheet also gives the info for all the core pracs you need to know - got it from another thread
    a2 biology core practical summary - The Student Room

    My teacher says what you need to know bout a prac to get most marks on a core prac Q is:
    C - Controls - (Bit misleading I know) - What are dependent and Independent variables. NA tot his experiment
    O - Organism - How are you treating the organism? if you are measuring breathing you need to only put them on for a short amount of time so the chamber isn't emptied of oxygen and thus ensure the subject doesn't die from asphyxiation ( a bit melodramatic but you get the idea). You need to give them time to acclimatise to breathing through a tube.
    R - Repeats - ALWAYS DO SAY YOU DO REPEATS
    M - Measurements - What are you actually measuring. If you are doing an expt on Heart rate you are measuring the number of beats in a set amount of time - Kind of difficult with this expt but you are recording trace on spirometer. The say you
    S - Same or Safety - What do you need to keep the same - Original amount of oxygen in the chamber - Depends on Q - If its bout effect of exercise - How long are they exercising. what intensity of exercise. etc
    Safety - what do you need to do to ensure the safety of the person carrying out the experiement (not really that important in this example) and the safety of the human subject(THIS!)

    If you can't be bothered or have too much else to look at or do any of the stuff above there is a Q on this on Q4 Jan13 , Q4 Jun12 and Q3 Jun11. Learn the mark scheme.

    Hope that helps. If anyone else has anything else to add which I missed could you tell me.
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    Hi Guys,

    Could somebody please please explain the specific immune response? My teacher barely touched on it, and the textbooks seem to go into information overload!
    I'd really appreciate any help on the cell mediated and humoral response like you wouldn't believe!
    Thank you
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    (Original post by TrentAlistar)
    http://www.snabonline.com/content/to...ts/a7_13sb.pdf
    This is the practical sheet could be useful to you if you don't already have it

    Also, you can search up a demonstration on youtube to go with prac sheet. Read prac sheet first, then look at a video.

    If you look at sheet A it has Qs on the subject to ensure you understand prac
    http://www.snabonline.com/content/to...ts/a7_13sa.pdf

    This sheet also gives the info for all the core pracs you need to know - got it from another thread
    a2 biology core practical summary - The Student Room

    My teacher says what you need to know bout a prac to get most marks on a core prac Q is:
    C - Controls - (Bit misleading I know) - What are dependent and Independent variables. NA tot his experiment
    O - Organism - How are you treating the organism? if you are measuring breathing you need to only put them on for a short amount of time so the chamber isn't emptied of oxygen and thus ensure the subject doesn't die from asphyxiation ( a bit melodramatic but you get the idea). You need to give them time to acclimatise to breathing through a tube.
    R - Repeats - ALWAYS DO SAY YOU DO REPEATS
    M - Measurements - What are you actually measuring. If you are doing an expt on Heart rate you are measuring the number of beats in a set amount of time - Kind of difficult with this expt but you are recording trace on spirometer. The say you
    S - Same or Safety - What do you need to keep the same - Original amount of oxygen in the chamber - Depends on Q - If its bout effect of exercise - How long are they exercising. what intensity of exercise. etc
    Safety - what do you need to do to ensure the safety of the person carrying out the experiement (not really that important in this example) and the safety of the human subject(THIS!)

    If you can't be bothered or have too much else to look at or do any of the stuff above there is a Q on this on Q4 Jan13 , Q4 Jun12 and Q3 Jun11. Learn the mark scheme.

    Hope that helps. If anyone else has anything else to add which I missed could you tell me.
    Thank you! That was really informative and much more than I was expecting. I'll definitely take a look at the SNAB sheets and look up the past papers. I've seen a question on spirometers before but didn't know what to put.
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    (Original post by shooting_stars)
    Hi guys, for unit 5 what do we need to know about acetylcholine?
    all you need to know is the fact that acetyl-choline is excitatory and involved in skeletal mucle contraction. Also glutamate is excitatory and is involved in learning, it is released at the synapse when rod cell is depolarised in dark light and inhibits the bipolar neurone (hypoerpolarised) therefore no impulse to the optic nerve

    depolarised = the inside of the membrane becomes more positive than outside
    re polarised = the inside of the axon is more negative than outside
    neurotransmitter = a transmitter substance which carries the impulse across the synaptic cleft, binds to receptors on the post synaptic membrane and results in depolarisation due to an influx of Na+

    hope this helps x
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    (Original post by lucyhan2323)
    Hi Guys,

    Could somebody please please explain the specific immune response? My teacher barely touched on it, and the textbooks seem to go into information overload!
    I'd really appreciate any help on the cell mediated and humoral response like you wouldn't believe!
    Thank you
    Specific Immune response
    - occurs when a specific pathogen is identified as foreign matter
    - Macrophage is attracted by chemical signals and engulfs
    - pathogen is encased in phalgosome of which lysosome releases lysozymes resulting in hydrolysis
    - as a result antigen binds to MHC (major histacompatability complex) which binds to the cell surface, cell becomes an APC (antigen presenting cell)
    - inactive T-helper cells are activated by their specific CD4 receptors binding to the specific antigen .
    - t helper cells release cytokines
    HUMMORAL RESPONSE : (outside the cell )
    - B cells are activated
    -B cells increase in number by mitosis into B effector and B Memory cells
    - B effector cells differentiate into Plasma cells which produce antibodies
    - the antibodies undergo aggulation to allow chemical signals to attract phagocytes
    CELL MEDIATED RESPONSE : (inside the cell)
    - T cells undergo clonal expansion to produce T killer and T memory cells
    - T killer cells congregate pathogen and release cytotoxins
    -t killer cells also release lymphokines to stimulate production of more t killer cells and signals back up to macrophages
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    (Original post by etherealinsanity)
    Could someone please explain how to do the spirometer core practical. My teacher couldn't figure out how to use the machine so we didn't do it and then she made us sign the sheet saying we'd done all the core practicals.
    i gurantee you this will get you full marks if you remember all of this x
    The spirometer trace
    -ventilation rate = tidal volume x breathing rate
    -Volume tube is calibrated
    -Time is calibrated
    -The tidal volume for each subject can be measured by the height from peak to trough
    -One breath = one breath
    -Breathing rate = number of peaks per minute
    -traces should be taken at rest
    -each subject should be the same gender and age
    -Repeat the experiment several times to gather a mean+ more reliable
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    (Original post by tayloryeah)
    Specific Immune response
    - occurs when a specific pathogen is identified as foreign matter
    - Macrophage is attracted by chemical signals and engulfs
    - pathogen is encased in phalgosome of which lysosome releases lysozymes resulting in hydrolysis
    - as a result antigen binds to MHC (major histacompatability complex) which binds to the cell surface, cell becomes an APC (antigen presenting cell)
    - inactive T-helper cells are activated by their specific CD4 receptors binding to the specific antigen .
    - t helper cells release cytokines
    HUMMORAL RESPONSE : (outside the cell )
    - B cells are activated
    -B cells increase in number by mitosis into B effector and B Memory cells
    - B effector cells differentiate into Plasma cells which produce antibodies
    - the antibodies undergo aggulation to allow chemical signals to attract phagocytes
    CELL MEDIATED RESPONSE : (inside the cell)
    - T cells undergo clonal expansion to produce T killer and T memory cells
    - T killer cells congregate pathogen and release cytotoxins
    -t killer cells also release lymphokines to stimulate production of more t killer cells and signals back up to macrophages
    When you say cell mediated response (inside the cell), do you mean from the point at which a macrophage has engulfed the antigen? Are you following on from 't helper cells release cytokines'?
    and I'm guessing the humoral response is from an antigen which has not been engulfed by a phagocyte, right?
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    I highly recommend using this document for question 7, for unit 5, it has helped me massively understand the context of the article - it also has given me loads of practice on potential questions and edexcel specific model answers { https://www.tes.com/teaching-resourc...-aids-11271853 }
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    (Original post by mechanism)
    When you say cell mediated response (inside the cell), do you mean from the point at which a macrophage has engulfed the antigen? Are you following on from 't helper cells release cytokines'?
    and I'm guessing the humoral response is from an antigen which has not been engulfed by a phagocyte, right?
    yes im following on from t helper cells release cytokines then the different responses follow depending on the situation .
    all specific responses occur after the ingesting of an antigen so that it can be presented by a an APC and so that t helper cells can be activated to release cytokines to activate the other immune cells ( its a bit of a cascade of events )

    and yes cell mediated response is the direct response to those mircobes that survive in phagcytes and microbes that infect non - phagocytic cells
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    (Original post by tayloryeah)
    I highly recommend using this document for question 7, for unit 5, it has helped me massively understand the context of the article - it also has given me loads of practice on potential questions and edexcel specific model answers { https://www.tes.com/teaching-resourc...-aids-11271853 }
    I understand that the article may help us, but please stop posting it lol. I've seen you post this many times.
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    (Original post by rory58824)
    I understand that the article may help us, but please stop posting it lol. I've seen you post this many times.
    im just trying to make people aware to try and help everyone and so it does not get lost, no hard feelings x
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    Hey does anyone know if the IAL papers and the R papers are the same spec as the normal UK ones?
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    how are people revising for pre release (BIO5)
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    (Original post by LThomas694)
    Hey does anyone know if the IAL papers and the R papers are the same spec as the normal UK ones?
    Certainly seem to be - I have been through them for revision and they have same sort of questions and same mark schemes....
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    (Original post by Moleyeyes)
    Certainly seem to be - I have been through them for revision and they have same sort of questions and same mark schemes....
    Okay that's great thanks!
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    (Original post by tayloryeah)
    Specific Immune response
    - occurs when a specific pathogen is identified as foreign matter
    - Macrophage is attracted by chemical signals and engulfs
    - pathogen is encased in phalgosome of which lysosome releases lysozymes resulting in hydrolysis
    - as a result antigen binds to MHC (major histacompatability complex) which binds to the cell surface, cell becomes an APC (antigen presenting cell)
    - inactive T-helper cells are activated by their specific CD4 receptors binding to the specific antigen .
    - t helper cells release cytokines
    HUMMORAL RESPONSE : (outside the cell )
    - B cells are activated
    -B cells increase in number by mitosis into B effector and B Memory cells
    - B effector cells differentiate into Plasma cells which produce antibodies
    - the antibodies undergo aggulation to allow chemical signals to attract phagocytes
    CELL MEDIATED RESPONSE : (inside the cell)
    - T cells undergo clonal expansion to produce T killer and T memory cells
    - T killer cells congregate pathogen and release cytotoxins
    -t killer cells also release lymphokines to stimulate production of more t killer cells and signals back up to macrophages


    Thank you so so much! You are a life saver!!! thank you thank thank you!
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    Question about the Unit 5 scientific article: in paragraph 25, it talks about the creation of a bacterial toggle switch: "collins announced the first artificial toggle switch in bacteria ; the scientists designed two promoters to interact and drive gene activity if prompted by one molecular signal and to stop when prompted again". Just wondering what all of that could mean??? Any ideas?
 
 
 
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