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    Let's go into Physics now ...
    http://www.thestudentroom.co.uk/show...xcel+physics+4
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    For physics people who are desperate.
    Go here > http://qchat.rizon.net/
    Choose a nickname
    and channel is PH4
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    (Original post by Doughboy)
    Question 1: >>two things you can use: rigor mortis and decomp
    >>reliability: at first it's reliable when Time After Death [TAD] is small. That's because we have a small standard deviation [SD] so core temperatures don't vary much. As T.A.D increases, S.D. increases which means the data has more variability and so less reliable. I kinda messed this up, so don't quote me on this!
    >>three factors: clothing, weight/mass/size of body, where body died, mode of death [needed to be specific]

    Nine marks! Two for MCQs, Four for reliability, Three for factors&cooling.
    Oops, i thought that since the standard deviations tend to overlap each other upto 8 hrs, it will not be reliable, but later on it becomes reliable. Quite the opposite.
    btw, how was your jan chem4?
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    (Original post by obviouslystudying)
    Oops, i thought that since the standard deviations tend to overlap each other upto 8 hrs, it will not be reliable, but later on it becomes reliable. Quite the opposite.
    btw, how was your jan chem4?
    Oh ok, not a lot of people knew about standard deviation. It's a how science works question [data analysis]. My 6CH04 went quite well. 120/120.
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    (Original post by Doughboy)
    Oh ok, not a lot of people knew about standard deviation. It's a how science works question [data analysis]. My 6CH04 went quite well. 120/120.
    Nah, I knew about standard deviation alright, just couldnt apply it correctly due to time restraint.
    Nice score on chem4. Hoping Im able to do extra good today so i can get rid of my practical paper woes.
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    The flowchart in question 4 got everyone in my year going :eek3: seriously what was all that about...we never learnt phagocytosis like that:hmmmm2:
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    i did a stupid mistake >:
    for the npp calculation,
    i miscalculated the value, but i actually wrote the correct equation:
    (24.4*10^6-3.7*10^6) / 24.4*10^6 X 100%

    will i get any marks for this?
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    (Original post by Doughboy)
    Question 8: Antibiotics

    bactericidal

    How vanco works? weakens cell walls [prevents bonds forming/crosslinking], places osmotic pressure on cells, cell lysis] 2 marks.

    2 marks on why docs should limit prescriptions. To prevent antibiotic resistance developing and something else? reducing selective pressures maybe..

    4 marker on everyone favourite core practical! Antibiotics and agar plate!
    1. Ref. to a specific aseptic technique
    2. Bacterial lawn/pour plate
    3. Use of antibiotic discs / antibiotics incorporated into agar
    /eq
    4. Incubate for 24-36 hours
    5. At 25-30 °C
    6. Record bacterial growth/eq

    9 marks.
    i wrote bacteriocical which was stated in the new text book >:
    argh should've followed bactericidal as i saw it while doing snab past year paper
    i feel really stupid!
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    (Original post by Roxychick)
    The flowchart in question 4 got everyone in my year going :eek3: seriously what was all that about...we never learnt phagocytosis like that:hmmmm2:
    That was childsplay ... all you had to know was well, yeah the whole process. HAHAHA,
    btw wat was teh answer to the next part ...
    I wrote it is the 2nd time the body has encountered this bacteria ...
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    (Original post by chocolates)
    i did a stupid mistake >:
    for the npp calculation,
    i miscalculated the value, but i actually wrote the correct equation:
    (24.4*10^6-3.7*10^6) / 24.4*10^6 X 100%

    will i get any marks for this?
    Your equation is right. answer should be 84.8%.
    HAHAHA, you will get 1 mark.
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    can we try and remember all the questions ...
    I'll give you guys all the MCQ answers -

    1- Muscle Contraction, signs of Decomposition.
    2- Respiration
    3- Hypothesis
    4- umm, Plasmid
    5- DAMN IT I can't remember ...
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    (Original post by samydude)
    Your equation is right. answer should be 84.8%.
    HAHAHA, you will get 1 mark.
    Oh dear. What was the question? I got 10/20-somthing %
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    Are you guys blind? Lol, I posted a semi-markscheme on the previous page.

    samydude, why would you say that he data is a hypothesis? I wanted to put that but not because of a logical reason...
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    Question 1: death and cooling
    Question 2: light, GPP, chloroplasts
    Question 3?: Species
    Question 4?: Immunity
    Question 5?: Growth rate and temperature
    Question 6?: Protein synthesis
    Question 7: Woodlice and girl
    Question 8: Antibiotics

    All ?s mean I can't remember the number! But those are the topics.
    ==============

    Question 1: >>two things you can use: rigor mortis and decomp
    >>reliability: at first it's reliable when Time After Death [TAD] is small. That's because we have a small standard deviation [SD] so core temperatures don't vary much. As T.A.D increases, S.D. increases which means the data has more variability and so less reliable. I kinda messed this up, so don't quote me on this!
    >>three factors: clothing, weight/mass/size of body, where body died, mode of death [needed to be specific]

    Nine marks! Two for MCQs, Four for reliability, Three for factors&cooling.
    ================
    Question 2:
    >>why all light not used or something? some not right wavelength, some reflected back, some passes right through
    >>84.8% of GPP
    >>Respiration [MCQ]
    >>Chloroplasts and ATP! Mention: photosystems, thylakoid, chlorophyll, light harvested, photoexcitation, electrons down transport chain, loss of energy from redox reactions, coupled to H+ pumping in, H+ diffuse out, this movement provides energy for ATP Synthase to drive phosphorlyation of ADP to make ATP. I guess you can mention photophosphorylation. Again, this isn't an expert answer... just a guide! I dunno if we needed the proton gradient points.

    11 Marks! 2 for light, 1 for respiration, 2 for %, 6 for chloroplast
    Edit/Delete Message
    ======================
    Question 3?: Species

    >>why scientists class them as varieties and not species? for three marks? I just put:
    similar characteristics/features, genes can flow between them, can reproduce to produce viable offspring, similar mating/flowering periods
    >>genetic diversity: variety of different alleles/genes within a population/gene pool.
    >>why hybrid more genetically diverse? cause it receives alleles from TWO varieties so it receives a greater variety of genes [im not sure about this!
    >>6 MARKER ON SPECIATION AND REPRODUCTIVE ISOLATION. Answer from sample:
    1. different (environmental) conditions in the different
    areas;
    2. different selective pressures;
    3. some fish better adapted than others (in each
    population);
    4. use of example of an adaptation from information;
    5. these more likely to survive to breed;
    6. and pass on their {alleles / genes} (to next generation);
    7. process of selection continues {in each generation / over
    many generations};
    8. allele frequencies of {favourable/eq} increases;
    9. correct use of term natural selection;

    13 marks! 3 for reasons why, 2 for genetic div. definitions, 2 for hybrid, 6 for speciation.
    ============================
    Question 4?: Immunity

    MCQ: histamine for inflammation, lysozyme for secretions

    Flow chart: antigen, plasma cell, antibodies, phagocytes, hydrolytic or digestive enzymes from lysozomes. [5 marks]

    Why the above processes may only be used on SOME bacteria? 3 marks. It's cause it was a secondary response! The body may have been infected by some bacteria before and become iummune against it. Maybe mention B memory cells. I hated this question so I dunno what to say?

    I think the total for this question is 10. Maybe 11 if there was an MCQ I missed out.
    =============================
    Question 5?: Growth rate and temperature

    We were told alga were eukaryotic:

    MCQs: mitosis for growth, plasmids for not present
    Independent variable? Temperature
    Describe graph? Growth rate increase up to 22 degrees. Decreases after. Refer to enzymes and metabolism and rate of reaction. Optimum at 22 degree. Denaturation beyond 22 degrees. 4 marks.

    Why high light intensity? 3 marks! I only got like a point, to ensure temperature was limiting factor. Under high light intensity you get maximum photosynthesis and food production so only factor affecting growth is temperature. I prolly got this wrong lol. Dumb question.

    Two abiotic factors to control: solution PH, salinity, O2 concentration?

    12 marks. two for mcq, one for variable, four for graph, 3 for explaining light and two abiotic.
    ==============================
    Question 6?: Protein synthesis

    I think we had to compare DNA and RNA for four marks in the table:
    1. str8 chain: RNA only
    2. pentose: both
    3. CGAT: DNA
    4. phosphodiester bonds: both

    Then this vague and retard six marker (in two parts, 3 each) on referring to their data for transcription and translation. I just simply described transcription and translation without referring to data. [6 marks]

    Why final codon didn't have corresponding tRNA? Stop codon maybe? Doesn't code for amino acid so not tRNA needed. Intron? 2 marks.

    12 marks! four for DNA/RNA, 6 for tras[scription/lation], 2 for codons at end
    ================================ =
    Question 7: Woodlice and girl

    MOST RETARDED QUESTION EVER.

    Woodlice and carbon cycle? 3 points. decompose, release enzymes, break down dead matter into organic molecules, they respire these molecules aerobically to release c02. [3]

    One mark for finding means. [1]

    What the girl's data was? I was tempted to put theory or hypothesis, but they asked for DATA... so i put OBSERVATIONS. Not sure! [1 mark]

    Why it's hard to find some abiotic something? Wtf?! Seriously what the hell were they asking us? 3 marks.

    Two abiotic factors on woodlice: light intensity, 02 conc., humidity [ two marks.]

    Total: 10
    =============================
    Question 8: Antibiotics

    bactericidal

    How vanco works? weakens cell walls [prevents bonds forming/crosslinking], places osmotic pressure on cells, cell lysis] 2 marks.

    2 marks on why docs should limit prescriptions. To prevent antibiotic resistance developing and something else? reducing selective pressures maybe..

    4 marker on everyone favourite core practical! Antibiotics and agar plate!
    1. Ref. to a specific aseptic technique
    2. Bacterial lawn/pour plate
    3. Use of antibiotic discs / antibiotics incorporated into agar
    /eq
    4. Incubate for 24-36 hours
    5. At 25-30 °C
    6. Record bacterial growth/eq

    9 marks.
    ================================ =
    The above 'mark scheme' is missing like 4 marks. Most of the paper is posted above anyway. Lemme hear your thoughts and if harder than January 2010 or not? Boundary predictions?
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    (Original post by samydude)
    That was childsplay ... all you had to know was well, yeah the whole process. HAHAHA,
    btw wat was teh answer to the next part ...
    I wrote it is the 2nd time the body has encountered this bacteria ...
    Yeah I knew phagocytosis
    1) phagocyte engulfs pathogen to become a phagosome
    2) fuses with a lysosome which contains digestive enzymes to break down the pathogen
    3) a phagolysosome is formed
    4) the phagolysosome then presents the pathogen's antigens and becomes an APC

    But the flowchart was nothing like that and that's what we learnt.
    For the second part I didn't really know either...I wrote about beneficial bacteria which aren't destroyed by the body. It was a non-specific response which meant there were no memory cells involved which is what confused me.
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    It wasn't JUST phagocytosis. It involved antibodies labelling the pathogen so that the phagoctyes could have found them.
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    I think this could have been a lot worse, hopefully done okay in this. Noticed it was out of 90 marks, aren't they normally out of 80? So hard to guess.

    Less random crap, pretty focused on the actual spec for once. Lovved the last question!
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    (Original post by Nereis)
    Noticed it was out of 90 marks, aren't they normally out of 80?
    The AS exam units are out of 80 for this spec. A2s are out of 90.

    http://www.edexcel.com/migrationdocu...4%20250510.pdf

    pg 8/9
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    (Original post by Doughboy)
    Are you guys blind? Lol, I posted a semi-markscheme on the previous page.

    samydude, why would you say that he data is a hypothesis? I wanted to put that but not because of a logical reason...
    I put prediction coz if its a hypohtesis wld she not have to have stated which abiotic factor she was going to experiment to see if tht was what was causing them to move. A theory has to be backed up with evidence andddd i cnt memba what the last one was but i put prediction just because it wasnt specific enough for the rest i didnt think.
    Do you think grade boundries will go up this year coz its not as complained about as last year?
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    I put theory because there weren't really any specifics. Figure hypothesis would have been more scientific.

    Anyone know the actual differences?
 
 
 
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