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Edexcel B3 unofficial markscheme 19th June 2017 Watch

  • View Poll Results: What mark do you think you got?
    55+
    23
    8.61%
    47-54
    98
    36.70%
    39-46
    88
    32.96%
    30-38
    41
    15.36%
    22-29
    12
    4.49%
    Under 22
    5
    1.87%

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    (Original post by Zaki1039)
    Dont think so because the plasmid the gave the name of is different to Bt toxin. I think you would have to mention it if it explicitly said so
    It was irrelevant to what toxin so it would just be ignored.
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    (Original post by sassyvoldemort)
    Nope it clearly said "MALE with haemophilia"
    Yeah i had to read the question like 3 times to make sure i actually get the percentage right, i got 25% since one of the genotypes was Xh Y which is a haemophilliac male
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    (Original post by oliver45456)
    It wasn't it said children
    Nope, a "boy" - it's a 3 marker question and they gave you what allele to use. The first mark is for correctly drawing the square. The second mark is for correctly identifing that the proberbility is out of the boy section. The third mark is for you correctly stating that out of the 2 boys who have a 50% chance of being born; given that they are a boy (as stated in the question), the chance of them inheriting the disease is out of those boys - 1/2 = 50%
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    1. https://www.thestudentroom.co.uk/sho...rimary_content

      THIS LINK FOR THE UNOFFICIAL MARK SCHEME COME AND HELP BUILD IT UP!!!





    Lets start a mark scheme

    1) Species 2
    b) C
    c) Co-evolution between moths and orchid
    4) Moth gets more nectar to itself/food

    2) Keeps them safe increasing chance of survival
    b) Primrose flowers are short day plants, helps them get pollinated by right insects.
    c) Caterpillars will not get eaten by the prey increasing chance of survival


    Punnet square question on haemophilia
    25%

    UREA is produced in the liver due to the breakdown of excess amino acids

    1st six marker
    Primary produces less antibodies as it takes longer for the B-lymphocytes to produce antibodies.
    However, it leaves memory lymphocytes behind.
    secondary infection, the memory lymphocytes produces a lot more in the SAME TIME (2 days) before we see the graph falling. IT takes longer for the graph to fall (the antibodies to lower) due to the abudnce of antibodies in the blood.
    primary response first infection of pathogen in body
    immune response is formed as lymphocytes divide and antibodies bind to the antigen
    destroy the pathogen, then memory lymphocytes are in the blood.
    A rapid secondary response is triggered with 2nd infection
    memory lymphocytes
    rapid response of lots of antibodies to destroy the pathogen, most likely before symptoms can be felt.

    HOW IS VEGETARIAN CHEESE PRODUCED? (4 MARKS)
    - made using CHYMOSIN
    - produced by GENETICALLY MODIFIED ORGANISMS
    - CHYMOSIN initiating CLOTTING
    -Chymosin and yeast production in fermenters
    - REDUCED use of RENNET (which is extracted from animals)

    2nd six marker
    lactose converted by lactase to glucose and galactose
    sodium alginate
    calcium chloride
    Keep the milk with the beads for around 15 minutes and at 40 degrees celcius. These are the optimum conditions.
    nylon guaze and syringe beads are put in
    Glucose test strip
    lactose encapsulated in beads
    glucose test strip shows it has been converted to glucose and galactose

    Transgenic plant question
    Restriction enzyme
    Ligases enzyme
    Sticky ends
    Vector
    Infects plant so DNA incorporated into plant
    crown galls

    This is what I have so far, if you could help me remember the question I can write more.
    comment your answers below !!
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    My final answer is 50%. It asked for the 'percentage of male haemophilics' meaning the percentage of males with haemophilia. correct me if I'm wrong.
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    (Original post by apk1)
    Think this settles the fact that the final answer is 50%. Science teacher agreed.
    Thank you! finally someone who isn't thick!
    • Thread Starter
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    [QUOTE=stephen1011;72279986]Thank you! finally someone It said what is the probability of the baby being a haemophiliac male
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    It was 25% lol. I asked my science teacher after and she said so
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    (Original post by stephen1011)
    Thank you! finally someone who isn't thick!
    It's 25%, it was the chance of the baby being male and a haemophiliac - not a male baby being a haemophiliac (which would have been 50%)
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    That paper was actually so easy apart from the last six marker, cuz like a donut I didn't revise it. But to be fair I have been doing all of my revision the night before. Ah well, you win some, you lose some.
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    (Original post by Amelia Louise)
    It's 25%, it was the chance of the baby being male and a haemophiliac - not a male baby being a haemophiliac (which would have been 50%)
    Word.
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    Think i got something between 47 and 51. could that be an A star
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    What was the answer for the ADH multiple choice question?
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    Please let it be 25%
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    Yes Oliver! You're on a roll mate!
    (Original post by oliver45456)
    Think i got something between 47 and 51. could that be an A star
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    (Original post by spikelee3138)
    Did anyone get the sacchromyces cervisiae for the yeast question?
    yh
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    I got angry at Edexcel when they asked what the name of the yeast for inveterate was. I don't speak Latin, it's supposed to be a multiple choice question
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    (Original post by hanzmamsmmx)
    i need the mark scheme where can i find it
    Did you find one?
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    The way the questions were worded in this paper were harder than the beat drop in Look At Me !_!
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    (Original post by oliver45456)
    Think i got something between 47 and 51. could that be an A star
    Definitely, a lot of peeps in my school found the exam hard. Hopefully the boundaries will be faiely low compared to last year as i feel this paper was much harder.
 
 
 
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