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AQA BIOL1 Biology Unit 1 Exam - 16th May 2011 watch

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    (Original post by Jubilee~)
    add benedicts reagent, if the colouring stays blue you add hydrochloric acid (i think) to break the disaccharide into it's monosaccharides. Then you add sodium hydrogen carbonate (i think) which because it's an alkaline will neutralise the acid.
    Then re-test with benedicts reagent and if a non reducing sugar is present, the colour will go from blue to orange/brown
    Spot on !! Nice one
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    (Original post by BeejTheone)
    Antibody has specific shape which is complemetary to that antigen gets you the mark?
    The enzyme bit was a different question.

    Basically the enzyme is used to find the pathogen.
    Ie tumour markers. They might use a drug. The enzyme is complimentry in shape no the antibody and the antibody is complimentry in shape to the antigen. If the antibody binds to the antigen and the enzyme binds fo the antibody you can locate the tumour.
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    (Original post by BeejTheone)
    How are lungs adapted to gas exchange?

    Explain Humoral and Cell mediated Response?

    EACH 5 MARKS
    Lungs have many alveoli which produce a large surface area for gas exchange. The alveoli is also thin to reduce the diffusion pathway. (cant think of anything else so do correct me lol)

    Cell mediated immunity -
    Pathogen is taken up by a phacocyte
    the phagocyte will then display the antigens from the pathogen on it's surface
    a certain t-helper cell will have a complimentary receptor to fit the antigen on the surface of the pathogen.
    This will activate other T helper cells to divide into clones by mitosis.
    These clones will -
    Stimulate phagocytosis
    Stimulate B Cells to divide
    Develop into memory cells which will prevent any future contact with the same pathogen
    And kill the pathogen...


    Cell mediated - (i hatethis one)
    A Certain B cell will display the antigen of the pathogen on it's surface
    A T- cell will then have receptors complimentary to this antigen.
    When it binds to the antigen it activates the B cells to divide into clones by mitosis
    it will develop into two types -
    plasma cells which have a short life span but they make a large number of antibodies to kill the pathogen.
    And into memory cells which will circulate the blood ready to make plasma cells if it comes into contact with the same pathogen again...


    is that right? just wrote down what i remember.
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    (Original post by BeejTheone)
    How are lungs adapted to gas exchange?

    Explain Humoral and Cell mediated Response?

    EACH 5 MARKS
    are these questions u made up
    or are these questions from the exam
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    (Original post by Rickesh)
    Lungs have alveoli that increase the surface area to volume ratio allowing for effcient gas exchange. The alveoli have thin walls so have a short diffusion pathway, so oxygen can diffuse rapidly. The alveoli are moist, again for effiient gas exchange. The alveoli have a good supply of blood to maintain the concentration gradient to allow oxygen to diffuse down its concentration gradient efficiently.

    Humoural is basically the B-cells that produce memory cells, and plasma cells that produce memory cells. So if the foreign antigen was to re-enter the body again, the memory cells would remember the antigen so there wouldnt be a primary response i.e. the person would not feel ill, there would be a quicker response so th person doesnt feel ill. Cell-mediated is basically how the T-cells work, i.e. they attach themselves to the antigens creating a antibody antigen complex?!?!? and then they stimulate the b-cells. Also the T killer cells kill the cell by various ways e.g. poking holes in the cell making it burst?

    Mark what you think I would have got out of 5 for each and where I could improve please !! thanks
    Nice answer

    1 Many alveoli / alveoli walls folded provide a large
    surface area;
    2 Many capillaries provide a large surface area;
    3 (So) fast diffusion;
    ________________________________ ________________
    4 Alveoli or capillary walls / epithelium / lining are thin /
    short distance between alveoli and blood;
    5 Flattened / squamous epithelium;
    6 (So) short diffusion distance / pathway;
    7 (So) fast diffusion;
    ________________________________ ________________
    8 Ventilation / circulation;
    9 Maintains a diffusion / concentration gradient;
    10 (So) fast diffusion;
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    (Original post by BeejTheone)
    How are lungs adapted to gas exchange?

    Explain Humoral and Cell mediated Response?

    EACH 5 MARKS
    The lungs contain numerous alveoli. This increases the surface area over which diffusion of oxygen into the blood can take place, thus increasing the rate of diffusion.
    The alveoli also have thin walls which means that diffusion takes place over a short distance, and so fast diffusion takes place.
    Uuum a concentration gradient is also maintained by the movement of an external medium i.e. blood
    The lungs are also moist which means that oxygen can be dissolved and diffuse into red blood cells in capillary.
    Lungs are ventilated which maintains a concetration gradient
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    These are previous questions from past papers
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    (Original post by BeejTheone)
    Nice answer

    1 Many alveoli / alveoli walls folded provide a large
    surface area;
    2 Many capillaries provide a large surface area;
    3 (So) fast diffusion;
    ________________________________ ________________
    4 Alveoli or capillary walls / epithelium / lining are thin /
    short distance between alveoli and blood;
    5 Flattened / squamous epithelium;
    6 (So) short diffusion distance / pathway;
    7 (So) fast diffusion;
    ________________________________ ________________
    8 Ventilation / circulation;
    9 Maintains a diffusion / concentration gradient;
    10 (So) fast diffusion;
    What about the other answer?
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    Cant find the second answers MS. But looks right to me
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    (Original post by BeejTheone)
    Cant find the second answers MS. But looks right to me
    OKay thankss How does emphysema cause shortness in breath ?
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    Yeah i think I would get like 5marks for the first answer?
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    (Original post by Jubilee~)
    Lungs have many alveoli which produce a large surface area for gas exchange. The alveoli is also thin to reduce the diffusion pathway. (cant think of anything else so do correct me lol)

    Cell mediated immunity -
    Pathogen is taken up by a phacocyte
    the phagocyte will then display the antigens from the pathogen on it's surface
    a certain t-helper cell will have a complimentary receptor to fit the antigen on the surface of the pathogen.
    This will activate other T helper cells to divide into clones by mitosis.
    These clones will -
    Stimulate phagocytosis
    Stimulate B Cells to divide
    Develop into memory cells which will prevent any future contact with the same pathogen
    And kill the pathogen...


    Cell mediated - (i hatethis one)
    A Certain B cell will display the antigen of the pathogen on it's surface
    A T- cell will then have receptors complimentary to this antigen.
    When it binds to the antigen it activates the B cells to divide into clones by mitosis
    it will develop into two types -
    plasma cells which have a short life span but they make a large number of antibodies to kill the pathogen.
    And into memory cells which will circulate the blood ready to make plasma cells if it comes into contact with the same pathogen again...


    is that right? just wrote down what i remember.
    Second asnwers good. compare 1st one with MS i posted
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    (Original post by ??????????????????)
    I'm on it!
    Mainly cos I've done that question a long time ago but need to remember it D:

    for III it's because if you don't wash it out you can still have sone left so if the antigens are not present you still get a positive result as they are stil there. Enzymes are related to the antibodies/gens because it's monoclonal. To see if they are infected, the enzyme is used. If it binds to the antigen it is infected.

    Ok, still confused (I'm a special brand of stupidity :P)

    I get steps 1 and 2 detailed in the question. They make perfect sense, what i don't get is:

    1. Why carry on? They've established the sample contains the antigen and so person is infected right?
    2. why use another antibody?
    3. The plate is washed at step 4, so what remains on the plate? antibodies are stuck to plate right? but haven't all the antigens gone?
    4. How on earth can an enzyme be complementary to an antigen?!

    Thanks
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    Okay so here's a question.


    Explain how the Cholera bacteria causes diarrhea in the patients
    - mention water potential etc.
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    I'm about to lock myself in my room for the next couple of hours to do some last minute cramming - so I just want to wish everyone good luck for tomorrow!
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    what have you guys been getting in the past papers? and how many raw marks is an A? does it say it on the AQA website?
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    would there by any chance that something to do with cancer would come up?
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    (Original post by Rickesh)
    OKay thankss How does emphysema cause shortness in breath ?
    Reduced elasticity; Lungs cant fully inflate, so less oxygen diffues through to the blood.

    Thicker walls, less gas exchange surface..

    Alveolar damages reduced Sa...

    Coz of all of these, Less respiration as less oxygen reaches respiring tissue so you're tired

    Somewhere along the lines of that?
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    (Original post by Rickesh)
    OKay thankss How does emphysema cause shortness in breath ?
    Results from difficulty in exhaling air due to loss of elasticity of the lungs and as the lungs cannot be emptied it becomes difficult to inhale fresh air containg O2 so patient feels breathless.
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    (Original post by Jubilee~)
    Okay so here's a question.


    Explain how the Cholera bacteria causes diarrhea in the patients
    - mention water potential etc.
    Cholera causes the chloride ion channels to open in the eptihelial cells of the small intestines. The chloride ions then move out of the cells into the lumen, lowering the water potenial of the lumen. Water therefore follows out of the blood into the lume from a high water potential to low, by osmosis
 
 
 
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