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

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    Hello!

    There's already a thread for Edexcel A2 Biology here: http://www.thestudentroom.co.uk/show....php?t=1905876

    However, most of the discussion going over there is regarding edexcel unit 5 revision so I thought it would be better to have a thread where everyone sitting for the Edexcel A2 Biology Unit 4 exam on the 15th of june 2012 could have a pre-exam discussion, ask and answer questions and doubts, share notes, ideas, tips, resources, helpful links and much more.

    To get started with, are you guys re-sitting the exam or sitting for it for the first time this session?
    The most obvious questions, how are you guys revising and what ways of revising help you most?
    How far have you gone in terms of exam preparation and revision?

    I have heard around that the CGP Revision Guide for Edexcel A2 Biology is excellent for revision so I really want to see how useful it actually is. However, I cannot get hold of it because I do not live in the UK so ordering it from the UK needs an almost double payment and almost 4-6 weeks of time. I was wondering if anyone here having it could please scan the pages from the CGP Edexcel A2 Biology Revision guide only from the Unit 4 section and upload them here individually, it would be very helpful.

    Thanks for reading my post. Hope this thread proves helpful to everyone using it.
    Good Luck revising!
    If it matters to anyone, +ve rep for anyone providing help!

    *I will be editting this post soon to add the Edexcel GCE Biology specification for unit 4 so that we can discuss each and every specification point, including the Core Practicals, fully. I will also be adding a link to an electronic version of the Edexcel A2 Biology Revision Guide which will indeed prove helpful for all.*
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    Topic 5: On the wild side
    Students will be assessed on their ability to:

    1 Demonstrate knowledge and understanding of the How Science Works areas listed in the table on page 13 of this specification.

    2 Describe the structure of chloroplasts in relation to their role in photosynthesis.

    3 Describe the overall reaction of photosynthesis as requiring energy from light to split apart the strong bonds in water molecules, storing the hydrogen in a fuel (glucose) by combining it with carbon dioxide and releasing oxygen into the atmosphere.

    4 Describe the light-dependent reactions of photosynthesis including how light energy is trapped by exciting electrons in chlorophyll and the role of these electrons in generating ATP, and reducing NADP in photophosphorylation and producing oxygen through photolysis of water.

    5 Describe how phosphorylation of ADP requires energy and how hydrolysis of ATP provides an immediate supply of energy for biological processes.

    6 Describe the light-independent reactions as reduction of carbon dioxide using the products of the light-dependent reactions (carbon fixation in the Calvin cycle, the role of GP, GALP, RuBP and RUBISCO) and describe the products as simple sugars that are used by plants, animals and other organisms in respiration and the synthesis of new biological molecules (including polysaccharides, amino acids, lipids and nucleic acids).

    7 Carry out calculations of net primary productivity and explain the relationship between gross primary productivity, net primary productivity and plant respiration.

    8 Calculate the efficiency of energy transfers between trophic levels.

    9 Discuss how understanding the carbon cycle can lead to methods to reduce atmospheric levels of carbon dioxide (including the use of biofuels and reforestation).

    10 Explain that the numbers and distribution of organisms in a habitat are controlled by biotic and abiotic factors.

    11 Describe how to carry out a study on the ecology of a habitat to produce valid and reliable data (including the use of quadrats and transects to assess abundance and distribution of organisms and the measurement of abiotic factors, eg solar energy input, climate, topography, oxygen availability and edaphic factors).

    12 Explain how the concept of niche accounts for distribution and abundance of organisms in a habitat.

    13 Describe the concept of succession to a climax community.

    14 Outline the causes of global warming – including the role of greenhouse gases (carbon dioxide and methane, CH4) in the greenhouse effect.

    15 Describe the effects of global warming (rising temperature, changing rainfall patterns and seasonal cycles) on plants and animals (distribution of species, development and life cycles).

    16 Explain the effect of increasing temperature on the rate of enzyme activity in plants, animals and micro-organisms.

    17 Describe how to investigate the effects of temperature on the development of organisms (eg seedling growth rate, brine shrimp hatch rates).

    18 Analyse and interpret different types of evidence for global warming and its causes (including records of carbon dioxide levels, temperature records, pollen in peat bogs and dendrochronology) recognising correlations and causal relationships.

    19 Describe that data can be extrapolated to make predictions, that these are used in models of future global warming, and that these models have limitations.

    20 Discuss the way in which scientific conclusions about controversial issues, such as what actions should be taken to reduce global warming or the degree to which humans are affecting global warming, can sometimes depend on who is reaching the conclusions.

    21 Describe how evolution (a change in the allele frequency) can come about through gene mutation and natural selection.

    22 Explain how reproductive isolation can lead to speciation.

    23 Describe the role of the scientific community in validating new evidence (including molecular biology, eg DNA, proteomics) supporting the accepted scientific theory of evolution (scientific journals, the peer review process, scientific conferences).


    Topic 6: Infection immunity and forensics

    Students will be assessed on their ability to:

    1 Demonstrate knowledge and understanding of the How Science Works areas listed in the table on page 13 of this specification.

    2 Explain the nature of the genetic code (triplet code, non-overlapping and degenerate).

    3 Explain the process of protein synthesis (transcription, translation messenger RNA, transfer RNA, ribosomes and the role of start and stop codons) and explain the roles of the template (antisense) DNA strand in transcription, codons on messenger RNA, anticodons on transfer RNA.

    4 Explain how one gene can give rise to more than one protein through post-transcriptional changes to messenger RNA.

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

    6 Describe how DNA can be amplified using the polymerase chain reaction (PCR).

    7 Describe how gel electrophoresis can be used to separate DNA fragments of different length.

    8 Distinguish between the structure of bacteria and viruses.

    9 Describe the role of micro-organisms in the decomposition of organic matter and the recycling of carbon.

    10 Describe the major routes pathogens may take when entering the body and explain the role of barriers in protecting the body from infection, including the roles of skin, stomach acid, gut and skin flora.

    11 Explain how bacterial and viral infectious diseases have a sequence of symptoms that may result in death, including the diseases caused by Mycobacterium tuberculosis (TB) and Human Immunodeficiency Virus (HIV).

    12 Describe the non-specific responses of the body to infection, including inflammation, lysozyme action, interferon and phagocytosis.

    13 Explain the roles of antigens and antibodies in the body’s immune response including the involvement of plasma cells, macrophages and antigen-presenting cells.

    14 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.

    15 Explain how individuals may develop immunity (natural, artificial, active, passive).

    16 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).

    17 Distinguish between bacteriostatic and bactericidal antibiotics.

    18 Describe how to investigate the effect of different antibiotics on bacteria.

    19 Describe how an understanding of the contributory causes of hospital acquired infections have led to codes of practice relating to antibiotic prescription and hospital practice relating to infection prevention and control.

    20 Describe how to determine the time of death of a mammal by examining the extent of decomposition, stage of succession, forensic entomology, body temperature and degree of muscle contraction.
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    Urgh, Topic 5 makes me want to gauge my eyes out
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    (Original post by marc_h94)
    Urgh, Topic 5 makes me want to gauge my eyes out
    I hate it too
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    (Original post by d_94)
    Hellooz (: I'm doing the exam for the first time. And is there any revision tips? I'm studying the nervous system; Chapter 8.2. Wbu?
    The nervous system chapter is included in Unit 5 and not Unit 4. This thread is for unit 4 june 2012 exam discussions.
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    (Original post by marc_h94)
    Urgh, Topic 5 makes me want to gauge my eyes out
    But why? Any specific areas u r facing difficulties in? Hope I can help.
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    (Original post by d_94)
    I hate it too
    Have you got any doubts? Maybe I can help and asking questions and answering them would hopefully be helpful to both you and me.
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    (Original post by M Kh)
    Have you got any doubts? Maybe I can help and asking questions and answering them would hopefully be helpful to both you and me.
    A quick questions guys :

    1. Do you have to know about the structure of a pholem and how its adapted to it functions?
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    (Original post by arnab)
    A quick questions guys :

    1. Do you have to know about the structure of a pholem and how its adapted to it functions?
    You have to revise everything from the AS Specification. I assume we have to know the structure and function of phloem according to the Edexcel AS Biology specification. Please correct me if I am wrong.
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    i assume in unit 4 you wont be asked about AS material directly and purely but you need knowledge from that in order to answer the questions? as in they will blend the content together :P
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    (Original post by M Kh)
    You have to revise everything from the AS Specification. I assume we have to know the structure and function of phloem according to the Edexcel AS Biology specification. Please correct me if I am wrong.
    I dont remember learning about the pholem any where in unit1 or 2
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    (Original post by kitriviolet)
    i assume in unit 4 you wont be asked about AS material directly and purely but you need knowledge from that in order to answer the questions? as in they will blend the content together :P
    Oh yes, you are right. Thanks for the clarification.

    So guys do you have any practice questions on the CORE PRACTICALS?
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    (Original post by arnab)
    I dont remember learning about the pholem any where in unit1 or 2
    I only remember learning about the xylem, sclerenchyma and parenchyma fibres and not in much detail about the phloem fibres. Someone please do confirm.

    Check the specification for Edexcel GCE Biology for unit 2 on the Edexcel's website for clarification.
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    Can anyone help me with this, please? What do we have to know for the following specification point:

    13 Explain the roles of antigens and antibodies in the body’s immune response including the involvement of plasma cells, macrophages and antigen-presenting cells ??
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    (Original post by M Kh)
    I only remember learning about the xylem, sclerenchyma and parenchyma fibres and not in much detail about the phloem fibres. Someone please do confirm.

    Check the specification for Edexcel GCE Biology for unit 2 on the Edexcel's website for clarification.
    Ahh cheers, i was thinking the exact same thing lol
    can someone please confirm whether we have to learn about pholem or not
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    (Original post by M Kh)
    I only remember learning about the xylem, sclerenchyma and parenchyma fibres and not in much detail about the phloem fibres. Someone please do confirm.

    Check the specification for Edexcel GCE Biology for unit 2 on the Edexcel's website for clarification.
    I've just checked the AS Unit 2 section of the specification and there is no mention of the phloem sieve tubes. They only say that you should be able to describe the structure and function of the xylem vessels and sclerenchyma fibres and identify them under a microscope. However just to be on the safe side, it wouldn't hurt to read up on phloem sieve tubes on the Internet or in a textbook.
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    (Original post by Cetacea)
    I've just checked the AS Unit 2 section of the specification and there is no mention of the phloem sieve tubes. They only say that you should be able to describe the structure and function of the xylem vessels and sclerenchyma fibres and identify them under a microscope. However just to be on the safe side, it wouldn't hurt to read up on phloem sieve tubes on the Internet or in a textbook.
    Ohhkay great.
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    Any resources for this external? Anyone??
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    Doing this exam too. Revision's been going well.
    Gonna revise it tomorrow.
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    (Original post by d_94)
    Any resources for this external? Anyone??
    Sorry, I don't understand what you mean. Can u please elaborate?

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