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OCR Biology F212 Revision [3rd June 2013] (Now Closed) watch

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    (Original post by Ché.)
    Thank you!
    Have you done a past paper before!?


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    No I haven't that's why I'm so worried! I had to revise is unit in one week since we had only just finished the content at school just before study leave... But tbh that's no one else's fault but my own I just hope my cramming pays off! Do you have any tips?


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    Someone please help me understand what T and B lympcytes are/do and what's the difference between them?
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    KK gone through everthing, apart from the enzyme practicals anyone know if we need to know those or just the biochemical tests.
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    (Original post by jamesmact)
    That's so helpful, thanks


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    pleaseeeee tell us what you predict?? :P
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    (Original post by morvenrkr)
    Someone please help me understand what T and B lympcytes are/do and what's the difference between them?
    (APC) Antigens presenting cells (infected cells and macrophages) present the antigens of an invading pathogen on their cell surface membrane.


    If the antigens come into contact with receptors cells on a T lymphocyte or antibodies on a B lymphocyte that are complementary to the antigen this will trigger clonal selection, selecting which cells have the complementary antibodies/receptors for the antigen. B lymphocytes, T killer and T helper lymphocytes are selected.


    T lymphocytes develop in the thymus and B lymphocytes develop in the bone marrow.


    T helper lymphocytes release interleukins and macrophages release monokines which stimulate B cells to differentiate.


    Clonal expansion now occurs. T and B lymphocytes divide by mitosis and differentiate. T lymphocytes become T killer, T helper and T memory cells. B lymphocytes become B memory cells and plasma cells.


    T killer cells attack infected host cells and release hydrogen peroxide which kills the cell.
    B and T memory cells remain in the blood and will stimulate clonal selection and expansion quickly if the pathogen re invades
    Plasma cells will release antibodies which will destroy pathogens by neutralisation and agglutination.






    That is what you would say In simple terms:


    APC's present antigens
    B and T lymphocytes with complementary receptors/antibodies are clonally selected.
    T helper cells stimulate B lymphocytes
    They undergo clonal expansion, diving by mitosis and differentiating
    Plasma cells release antibodies
    T Killer cells attack and kill infected cells
    Memory cells remain in the blood for a long period after the pathogen has been destroyed


    Thats all you really need to know on them (thats the whole immune response basically)
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    Done 4 past papers and got 4 A'so far and did the may 12 one too which is the hardest one of them all and got 82,yet I still feel idk everything


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    Anyone up for revision !


    Lets do immunity ,


    Describe the role of antibodies and describe the structure using the words heavy chain and light chain (6 marks)
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    (Original post by otrivine)
    Anyone up for revision !


    Lets do immunity ,


    Describe the role of antibodies and describe the structure using the words heavy chain and light chain (6 marks)
    Antibodies have 4 polypeptide chains, 2 light chains and 2 heavy chains.
    They are held together by disulfide bonds.
    The hinge region allows flexibility.
    The constant region is the same for all antibodies and allows for the antibodies to attach to phagocytes, during phagocytosis,
    The variable region is complementary shaped to a specific antigen, it allows the antibody to attach to an antigen.
    There are more than one variable regions, which means that the antibody can neutralise more than one antigen at a time.
    Antibodies can agglutinate pathogens, this clumps them together making them too large to enter host cells as well as more easily identifiable by macrophages.
    They can also neutralise pathogens, by blocking their antigens, preventing them from entering host cells.
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    What's the difference between amylose, amylopectin and starch? Are they all types of starch or is starch made up of amylose and amylopectin molecules? The book's really confusing :/
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    (Original post by xKaylax)
    What's the difference between amylose, amylopectin and starch? Are they all types of starch or is starch made up of amylose and amylopectin molecules? The book's really confusing :/
    Starch is made up of amylose and amylopectin
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    (Original post by Gotzz)
    Antibodies have 4 polypeptide chains, 2 light chains and 2 heavy chains.
    They are held together by disulfide bonds.
    The hinge region allows flexibility.
    The constant region is the same for all antibodies and allows for the antibodies to attach to phagocytes, during phagocytosis,
    The variable region is complementary shaped to a specific antigen, it allows the antibody to attach to an antigen.
    There are more than one variable regions, which means that the antibody can neutralise more than one antigen at a time.
    Antibodies can agglutinate pathogens, this clumps them together making them too large to enter host cells as well as more easily identifiable by macrophages.
    They can also neutralise pathogens, by blocking their antigens, preventing them from entering host cells.
    6 marks, excellent work Gotzz

    can you ask me please
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    (Original post by otrivine)
    Anyone up for revision !


    Lets do immunity ,


    Describe the role of antibodies and describe the structure using the words heavy chain and light chain (6 marks)
    Antibodies are produced by Plama Cells, when an Antibody comes in contact with an Antigen it forms an Antigen-Antibody complex. Antibodies contain 2 Heavy Polypeptide chains at the base of the Antibody and 2 Light Polypeptide Chains at the top of the Antibody

    Many disulphides bridges form on the Polypeptide chains to prevent the chains from breaking apart

    The Antibody has a Variable Region which is different for all Antibodies, this is where an Antigen with a Complementary shape attaches

    The Antibody also has a Constant Region which is the same in all Antibodies which is where Phagocytes will bind

    The Hinge Region between the Heavy and Light Polypeptide Chains allows flexibility of the Antibody
    Roles:
    Agglucination of Pathogens, basically more pathogens are phagocytosis due to the Antibody containing 2 Binding sites
    Neutralise Toxins, can't bind to toxins basically
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    (Original post by otrivine)
    6 marks, excellent work Gotzz

    can you ask me please
    Describe the differences between the primary and secondary response (4)
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    (Original post by Gotzz)
    Describe the differences between the primary and secondary response (4)
    Primary response is where the concentration of antibody is much less and in secondary response the concentration of antibody is much more and takes place usually around day 31. The reason for the natibody production being less in primary response is because if an pathogen enters the host cell and is foreign to the body (Cells) then the lymphocytes have to be activated in which the cytokines that are the second messengers have to bind to the cell surface receptor of the lymphocyte in order to activate a specific lymphocyte which could either be T or B. Then the lymphocyte have to under go clonal selection and expanssion in which it takes time for them to divide by mitosis and once they divide they can differentiate to specific cell types making antibodies( B lymphocyte--> plasma celll--> memory cell--> antibody) for example which remain in the blood/body to provide long term immunological memory and this arises to give the secondary response.
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    (Original post by OHK567)
    Antibodies are produced by Plama Cells, when an Antibody comes in contact with an Antigen it forms an Antigen-Antibody complex. Antibodies contain 2 Heavy Polypeptide chains at the base of the Antibody and 2 Light Polypeptide Chains at the top of the Antibody

    Many disulphides bridges form on the Polypeptide chains to prevent the chains from breaking apart

    The Antibody has a Variable Region which is different for all Antibodies, this is where an Antigen with a Complementary shape attaches

    The Antibody also has a Constant Region which is the same in all Antibodies which is where Phagocytes will bind

    The Hinge Region between the Heavy and Light Polypeptide Chains allows flexibility of the Antibody
    Roles:
    Agglucination of Pathogens, basically more pathogens are phagocytosis due to the Antibody containing 2 Binding sites
    Neutralise Toxins, can't bind to toxins basically
    Full marks

    ask me please
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    (Original post by Gotzz)
    Describe the differences between the primary and secondary response (4)
    Primary Secondary
    Slow Fast
    Produces Symptoms No Symptoms
    Pathogens enter for the 1st time Pathogens enter for the 2nd time
    Activates B and T lymphocytes Activates Memory Cells
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    Define Ex Situ Conservation (2 marks)
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    (Original post by otrivine)
    Primary response is where the concentration of antibody is much less and in secondary response the concentration of antibody is much more and takes place usually around day 31. The reason for the natibody production being less in primary response is because if an pathogen enters the host cell and is foreign to the body (Cells) then the lymphocytes have to be activated in which the cytokines that are the second messengers have to bind to the cell surface receptor of the lymphocyte in order to activate a specific lymphocyte which could either be T or B. Then the lymphocyte have to under go clonal selection and expanssion in which it takes time for them to divide by mitosis and once they divide they can differentiate to specific cell types making antibodies( B lymphocyte--> plasma celll--> memory cell--> antibody) for example which remain in the blood/body to provide long term immunological memory and this arises to give the secondary response.
    You could also mention that the delay time, before the concentration of antibodies begins to increase, is much quicker in the secondary response.
    But good answer, the main points to make are secondary:
    More antibodies produced
    Antibodies produced at a faster rate
    Shorter delay time
    ETA: oh and mention the symptoms (none occur during secondary)
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    em wait am so amylopectin is branched but not because of 1-6 bonds? i thought glycogen only contained 1-6's for quicker energy release. and em anyone gimme a quick run down on there structure and functions plox
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    (Original post by Gotzz)
    You could also mention that the delay time, before the concentration of antibodies begins to increase, is much quicker in the secondary response.
    But good answer, the main points to make are secondary:
    More antibodies produced
    Antibodies produced at a faster rate
    Shorter delay time
    ETA: oh and mention the symptoms (none occur during secondary)
    will I not get the 4 marks, thought that was enough
 
 
 
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