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Edexcel A2 Biology Unit 4 (6BI04) - 15 June 2012 - Official Exam Discussion Thread!!!

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    (Original post by demdil)
    i have 5 exams left too unit 4/5 biology and chemistry and maths c4 .. ahh too much :/ and i keep wasting time as if its the summer holiday or smthng.. because i'm tired of these examss..
    I have those exams left too :five:

    We're still not on study leave
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    Any predictions on what core prac may come up?

    What sort of questions do you think will come up too,
    I haven't seen a peat bog question in a while,
    something about rigor mortis?
    Succession?

    I doubt HIV or TB will come up for a big question cos they have come up recently i believe
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    heyy guys!
    Can someone please please explain to me the specific response of the immune system?? What are the roles played by the antigens, antibodies, plasma cells, macrophages and antigen-representing cells

    Distinguish between the roles of B cells (including B memory and B effector cells) and T cells (T helper, T killer and T memory cells) in the body’s immune response.

    Discuss how the theory of an ‘evolutionary race’ between pathogens and their hosts is supported by the evasion mechanisms as shown by Human Immunodeficiency Virus (HIV) and Mycobacterium tuberculosis (TB).

    I just dont seem to get it
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    (Original post by vishalb)
    Any predictions on what core prac may come up?

    What sort of questions do you think will come up too,
    I haven't seen a peat bog question in a while,
    something about rigor mortis?
    Succession?

    I doubt HIV or TB will come up for a big question cos they have come up recently i believe
    I also haven't seen the antibiotics practical recently - it came up in June 2010 I think but may be due. I agree about the rigor mortis; I haven't seen a question such as "Explain how rigor mortis arises after death". Peat bogs may also come up because in January 2012 they asked about dendrochronology if I remember correctly.
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    (Original post by Cetacea)
    I also haven't seen the antibiotics practical recently - it came up in June 2010 I think but may be due. I agree about the rigor mortis; I haven't seen a question such as "Explain how rigor mortis arises after death". Peat bogs may also come up because in January 2012 they asked about dendrochronology if I remember correctly.
    The antibiotic question can't come up as they gave a whole 10 mark question in the written alternative paper for unit 6
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    (Original post by vishalb)
    Any predictions on what core prac may come up?

    I doubt HIV or TB will come up for a big question cos they have come up recently i believe
    (Original post by Cetacea)
    I also haven't seen the antibiotics practical recently - it came up in June 2010 I think but may be due. I agree about the rigor mortis; I haven't seen a question such as "Explain how rigor mortis arises after death". Peat bogs may also come up because in January 2012 they asked about dendrochronology if I remember correctly.
    In the June 2011 exam, we had questions on all core practicals except the antibiotics one. It is highly likely that there will be atleast one question on HIV and/or TB because it always comes up and it is a very important part of the specification. Anyways, we better learn everything on the specification.
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    (Original post by aqua05)
    Can someone please please explain to me the specific response of the immune system?? What are the roles played by the antigens, antibodies, plasma cells, macrophages and antigen-representing cells
    Check the very first pages of this thread because someone has explained this earlier.

    (Original post by aqua05)
    Distinguish between the roles of B cells (including B memory and B effector cells) and T cells (T helper, T killer and T memory cells) in the body’s immune response.
    Check the Answers at the very last pages of the Edexcel A2 Biology Revision Guide because there's a table over there comparing the roles of these cells. Hope you fnd it.
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    (Original post by aqua05)
    Discuss how the theory of an ‘evolutionary race’ between pathogens and their hosts is supported by the evasion mechanisms as shown by Human Immunodeficiency Virus (HIV) and Mycobacterium tuberculosis (TB).
    This specification point asks us to be familiar with the evasion mechanisms that help the HIV and M. Tuberculosis bacterium to survive and win the 'evolutionary race' against their hosts (us).

    The HIV has a constantly evolving outer protein coat that prevents the host immune system from recognising and targeting it and so it survives, reproduces and only the HIV viruses best adapted will survive and go on to reproduce creating a population which is most efficient in targeting and killing the T-cells of the host immune system eventually weakening it. The host then develops multiple opportunistic infections like tuberculosis (TB), Kaposi's sarcoma (a type of cancer) and eventually dies due to this.

    The M. tuberculosis bacterium has an outer waxy coating that prevents the enzymes released by the macrophages of the host immune system from digesting the bacterium and so it survives remaining dormant in the deep tissues of the lungs until the host is malnourished and the immune system is weakened. The bacterium then becomes active again, multiplying continuoulsly and damaging the host lung tissue creating largely damaged areas in the lungs that are inefficient in air transfer. The host then dies either by lack of oxygen or by becoming weak due to malnourishment.
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    any care to explain the niche concept to me for unit 4 and what do i need to know/understand about it?
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    (Original post by aqua05)
    The antibiotic question can't come up as they gave a whole 10 mark question in the written alternative paper for unit 6
    In June 2011, we had the core prac about the effect of temp on growth in the unit 6B exam and then many students did not think that this core prac could come up again in the unit 4 exam but then we did have many questions based on this core prac. in the unit 4 exam in the same session.
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    (Original post by arnab)
    any care to explain the niche concept to me for unit 4 and what do i need to know/understand about it?
    I have a few notes about the niche concept. I will find them and try to post them here.
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    Can anyone please help me with what we need to know for paragraph 5 of topic 6 of the Edexcel GCE Biology Spec.:

    Describe how DNA profiling is used for identification and determining genetic relationships between organisms (plants and animals).

    Please do help. Thanks a lot in advance.
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    Hello, can you please help me in my previous post in this very thread?

    Please do help. Sincere thanks.
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    (Original post by M Kh)
    Hello, can you please help me in my previous post in this very thread?

    Please do help. Sincere thanks.
    I havent got my book with atm but will do in about 2hours, so will explain it once i get home and get my book
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    (Original post by M Kh)
    Can anyone please help me with what we need to know for paragraph 5 of topic 6 of the Edexcel GCE Biology Spec.:

    Describe how DNA profiling is used for identification and determining genetic relationships between organisms (plants and animals).

    Please do help. Thanks a lot in advance.
    DNA samples is taken from eg saliva, blood sample,etc and then you put it in the PCR machine for amplifying (Procedure of PCR). After this, you do DNA profiling (Electrophoresis).
    When placed under UV light you'll be able to see the bands. The more bands there are in the same position, the more closely related they are, and the more closely related they are it shows that they are likely to have a common ancester. This theory is mainly used to explain evolution

    PS- im assuming you know the procedure of PCR and electrophoresis.

    If you need more help quote me
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    Anyone got predictions?
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    the antibiotic practical came up in the june 2012 biology 6b. is that related? :P though i wouldnt be surprised if they stick the same practical in all a2 papers hah

    (Original post by Cetacea)
    I also haven't seen the antibiotics practical recently - it came up in June 2010 I think but may be due. I agree about the rigor mortis; I haven't seen a question such as "Explain how rigor mortis arises after death". Peat bogs may also come up because in January 2012 they asked about dendrochronology if I remember correctly.
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    Hello people!
    Helpful thread to start asking questions and support each other.

    Core practicals anyone?
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    (Original post by kitriviolet)
    the antibiotic practical came up in the june 2012 biology 6b. is that related? :P though i wouldnt be surprised if they stick the same practical in all a2 papers hah
    Not sure if they're related...best just learn it anyway!

    (Original post by katelv)
    Hello people!
    Helpful thread to start asking questions and support each other.

    Core practicals anyone?
    List of core practicals:

    Unit 4 Topic 5
    -Effect of temperature on organisms (seedling growth rates, brine shrimp hatch rates)
    -Investigating distribution of a named organism within a habitat

    Unit 4 Topic 6
    -PCR
    -Gel electrophoresis
    -Effectiveness of different antibiotics on bacteria

    Unit 5 Topic 7
    -Investigating rate of respiration in invertebrates (e.g. maggots or woodlice)
    -Data of breathing rate and tidal volume from spirometer traces

    Unit 5 Topic 8
    -Investigating habituation to a stimulus in snails
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    High chance of spirometer & respiratoer to come up.. habituation & antibiotic already came uip

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