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

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    Oxford,Cambridge and RSA
    Examinations (OCR)


    ~Molecules, Biodiversity, Food and

    Health F212~


    Date of exam: 3rd
    June F212 (50% of AS) (25% of A2)

    Specification Statement
    :http://www.ocr.org.uk/images/81028-specification.pdf

    Past Papers
    :
    http://www.ocr.org.uk/i-want-to/prepare-and-practise/past-papers-finder/
    Duration: 1 hour 45 minutes
    Maximum Mark:100

    ~Modules~
    *Biochemistry
    *Food, Health and Disease
    *Ecology

    AS Endorsed Textbook
    Name:  ohshshisahsaas.jpg
Views: 2081
Size:  44.4 KB

    Rules:
    No Off Topic Discussion (I.e physics discussion.)
    No asking questions that is not relevant (i.e if its not on the statement, we do no wish to know! As this will cause confusion!

    Revision Closed.


    Predicted Grade Boundaries



    A 70-71

    B 64

    C 59-60

    D 54

    E 48


    Official Grade Boundaries:
    A 69

    B 62

    C 56

    D 50

    E 44

    Unofficial Mark Scheme: Credit to
    Mule
    So here's my interpretation of the paper for anyone who wants to read (maybe TLDR :P)

    NOTE:4 marks are missing!

    Q1
    Name given to sequence of amino acids (1)
    I put primary structure

    Draw the structure of an amino acid (3)
    H2NCRHCOOH (drawn out)

    Why collagen is good for arteries (1)
    I put strong/tough to withstand high blood pressure, but i'm uncertain, flexibility probably would have been better.

    Describe the structure of collagen molecule (6)
    3 coiled polypeptide chains (quarternary structure) to form a rope
    Left hand helix shape
    Glycine is 1 in every 3 amino acids (smallest R group, close packing)
    Hydrogen bonds between polypeptides
    (now I'm not sure the next is right as it says the collagen molecule but I mentioned lysine's and covalent cross links
    I also said insoluble but I'm not sure thats part of structure,


    differences between structures collagen and haemoglobin (3)
    haemoglobin 4 polypeptide chains, collagen 3
    haemoglobin round and ball shaped, collagen straight
    haemoglobin has ionic bonds hydrophobic interactions and hydrophilic on outside maintaing tertiary structure, collagen does not



    Q2

    Type of biological molecule (1)
    Enzyme

    Why can it catalyse both (3)
    I talked about enzyme active site specificity complimentary to substrate. Both molecules have similar shapes/bonds, basically same except 2 less Hydrogen and 1 Oxygen in the DHP (or w/e it was called) So ESC forms.

    Why high ethanol concentration decreases toxicity (3)
    I said they both compete for the active site, where ethanol is present it will enter and stop DHP from entering. So less DHP can be broken down in the same amount of time, so toxic products formed slower, so body can remove these before concentration increases too much.

    Q3
    Infective agent of TB (1)
    Mycobacterium tuberculosis

    How its transmitted (2)
    Exhaled droplets of moisture by infected person inhaled by uninfected people, through coughing, sneezing, laughing, talking (I think you could also mention cattle meat for M.Bovis)

    Describe the data between 2000 and 2008 (3)
    I said low income and middle low stay the same (figures)
    Medium upper increases I think it was and upper decreases
    Both years low is highest incidence, upper is lowest incidence]

    Why low income have greater incidence (3)
    More likely to have malnutrition
    Unable to afford vaccines/antibiotics or take antibiotics when needed
    Overcrowding and sleeping as cannot afford to buy separate houses

    Q4.
    Which cells are phagocytes? (1)
    I put just C although apparently B is too but it looks just as similar to a lymphocyte and a monocyte in my opinion so there should hopefully be allowance in the MS.

    Why "secondary"? (1)
    After primary defence breached, part of immune response to antigens

    Why "non-specific"? (1)
    Can attach to any foreign antigens

    How can cells in (a) pass into tissue fluid from blood (2)
    Have lobed nucleus so can squeeze in thin spaces between walls of cells in the capillary
    (other people have mentioned histamines)

    What happens after pathogen attaches to phagocyte? (7)
    Engulfed, membrane infolds, phagocytosis, endocytosis
    Phagosome formed
    Lysosomes move towards and fuse with phagosome
    secrete hydrolytic enzymens/lysins
    break down/digest pathogen
    Into soluble products (e.g. amino acids)
    absorbed into cytoplasm
    waste excreted
    macrophages can become APC's

    Q5.

    Calculate SI of Diversity (3)
    I got 0.6 something

    Species richness (1)
    Number of species present in an area

    Species evenness (1)
    Relative numbers of individuals of each species present in an area

    Low SI Index (2)
    Low biodiversity suggests dominated by few species
    If environmental change, habitat cannot adapt, dependence on that species

    Improve accuracy of sampling (2)
    use random sampling, random coordinates generated by calculator
    Repeat at different times of month/year (I was thinking about selecting suitable quadrate size but chose the other)

    Q6.
    There's a 1 mark question here I can't quite remember, something about genetic variation I think (1)

    Why crop yield varies (2)
    I put insecticides used to stop disease spread, resistance to insecticides, use of fertilisers, climate change (temp/rainfall)

    How genetic variation arises (1)
    Mutation (i wondered if you could put sexual reproduction also)

    Selective breeding short term + long term (7)
    I said this is artificial selection
    Select wild varieties with resistance and cross breed
    prevent asexual reproduction
    Select offspring with resistance and highest yield
    Cross breed again
    repeated for many generations - this is all short term
    Then long term - mutations can cause pathogens to change
    Conserve wild plants, botanic gardens, seed banks, potential of alleles to other diseases
    Multiple alleles to provide better protection
    I also mentioned gene marking somewhere

    I have to admit this question threw me a bit though

    Q7.
    define biodiversity (2)
    Variety of life, range of living species, habitats and communities and the ecosystems of which they form a part
    Genetic variation within and between species

    Why conservation methods needed for the specific area (2)
    Important part of food chains
    Tourism, aesthetically pleasing ( I wonder if you could also put gene pool etc.)

    Suggest why people against culling (1)
    I said morally wrong, inhumane to trap and kill just to keep population down

    Why red squirrel population may be higher than counted (2)
    Grey squirrels not intimidated by humans, red hiding, not seen
    red have better camouflage for red trees, not seen (not sure this is right)

    EIA criteria (3) (did not like this one)
    Effect on biodiversity, environmental sensitivity due to noise pollution (wind turbines)
    whether there are any endangered species (e.g. red squirrel)
    Method to reduce impact (e.g. translocation of red squirrels)

    Q8.
    Components of DNA (2)
    Nitrogenous organic base (I put cytosine as well because it was next to G)
    Nucleotide

    Draw Hydrogen bonds between polynucleotides (2)
    3 between C and G
    2 between A and T

    Complete gaps (2)
    Polypeptide
    Ribosome

    How RNA would be different to DNA (2)
    RNA would be single stranded
    RNA would have U instead of T

    Why it is "semi-conservative" (2)
    2 DNA molecules produced, each has one old strand and 1 new strand forms by new nucleotides.

    Why complementary base-pairing is important (2)
    identical molecules of DNA are produced
    so exact protein is made
    purine to pyramidine
    Different base would be mutation, different protein

    Draw in the R1 and R2 (2)
    For R1 I did a line between the N15 line and the N14 line
    For R2 I did half a line at the same position as R1 and the other half at N14

    3 precaution in centrifugation (3)
    Same concentration of sugar solution
    Same volume of sugar solution
    Same time for centrifugation

    Q9
    Fill space (5)
    Whatever the genus was
    I think I got order
    I think I got phylum
    Kingdom = Animalia
    Domain = Eukaroyta

    Phylogeny (3)
    Study of evolutionary relationships, involves ancestral trees
    Classification, placing organisms in groups based on similarities (biochem/anatomy)
    Phlyogeny shows how recent is the common ancestor, more recent = more similarities
    therefore organism placed in similar groups
    less time for mutation/variations to arise

    Why water bear was undiscovered (2)
    Too small to be seen
    Microscopes were not available
    Also talked about speciation because it did say
    why were they not discovered "before 300 years" I think.

    Anyway, these are my answers, they may not necessarily be correct, just for people to make comparisons



    F214 June 2013 Revision can be found here

    F215 June 2013 Revision can be found here


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    I thought it was 50% of AS?
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    (Original post by bobsmith657)
    I thought it was 50% of AS?
    It is. It is 25% of overall A Level
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    Fixed thread to fix misunderstanding
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    Lets begin with some revision

    Define the term Variation (2)
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    I am currently starting revision videos on youtube. I have done one on water, please check it out and tell me what you think, if i should continue, tips on how to improve anything, Ill do more frequent ones if people like them http://www.youtube.com/watch?v=EUo6P...ature=youtu.be
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    (Original post by Munrot07)
    I am currently starting revision videos on youtube. I have done one on water, please check it out and tell me what you think, if i should continue, tips on how to improve anything, Ill do more frequent ones if people like them http://www.youtube.com/watch?v=EUo6P...ature=youtu.be
    Very good videos!
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    Keep it up!
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    (Original post by BioGeek)
    Keep it up!
    thanks just hoping to get a few more video views and likes and subscribers :P
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    *subscribed*
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    any1 up for revision????

    exams are fast approaching....
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    (Original post by BioGeek)
    any1 up for revision????

    exams are fast approaching....
    I think revision would be useful :P really nervous about the exam though luckily i don't need a massively high mark in it :P
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    this exam can **** right off
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    ATTENTION ALL: Just did an F212 past paper with the book and got 80%..am I shafted? I think so, yes.
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    (Original post by upthegunners)
    ATTENTION ALL: Just did an F212 past paper with the book and got 80%..am I shafted? I think so, yes.
    It's not so bad after you do a few... you just need to know the markscheme's well.
    BTW I'm an A2 student re-sitting this paper (got a high B last year :L) and markschemes is where I fell down really
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    (Original post by Sherlockedd)
    It's not so bad after you do a few... you just need to know the markscheme's well.
    BTW I'm an A2 student re-sitting this paper (got a high B last year :L) and markschemes is where I fell down really
    They are so pedantic about the answers

    so annoying
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    There is a trick for revising extra for relevant topics. You wilk see as you look through part papers there's a pattern to questions asked. For exampl they will ask a osmosis question last year abd that will definitely not come up this year. If you have a good teacher they should come up with possible / likely questions that will come up.
    If they do not look at past paper and colour code how likely it is that certain topics will be asked
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    Hi peeps

    *subscribed*
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    (Original post by upthegunners)
    They are so pedantic about the answers

    so annoying
    It is so true, and it gets worse at A2 :L
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    Sooo.. I just got \frac{87}{100} in an F212 paper without a book.

    June 2011.

    \frac{73}{100} for an A in it according to the OCR website.

    I don't know if I should be pleased or not This was my first paper without using a textbook. However, I have done the paper before.. that slightly depresses me.

    What do you guys think?
 
 
 
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