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Edexcel B3 unofficial markscheme 19th June 2017 Watch

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  • 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 abz456)
    The question said they were in two equal groups
    Two equal groups that add up to 16000, so the answer was 24
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    6
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    Would you have to spell "sacchromyces cervisiae" correctly? Or would they accept sensible spelling?
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    (Original post by coldwarm34)
    Did the question state the group was exactly split into 8000, 8000? If not then you could have any amount in each group , you Gould have 10,000 in one and 6000 in the other
    It stated two equal groups explicitly.
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    I'm surprised anyone got saccharomyces cervisiae really, I don't think we were taught it and it's only 1 sentence in the revision guide that I brushed over.
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    Did we even learn that urine was produced in the liver?! swear it was the nephron but.......
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    (Original post by oliver45456)
    Did we even learn that urine was produced in the liver?! swear it was the nephron but.......
    It is but UREA is produced in the liver due to the breakdown of excess amino acids
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    What was the answer to the last 6 marker??
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    HOW IS LACTOSE-FREE MILK PRODUCED? (6 MARKS)

    - made using LACTASE
    - using EMBOLIZED enzymes
    - LACTASE converted into GALACTOSE and GLUCOSE
    - beneficial for people with LACTOSE INTOLERANCE
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    (Original post by apk1)
    - made using LACTASE
    - using EMBOLIZED enzymes
    - LACTASE converted into GALACTOSE and GLUCOSE
    - beneficial for people with LACTOSE INTOLERANCE
    and the lactase breaks down lactose into lactic acid
    Sodium alginate beads dropped into calcium chloride solution
    Lactic acid was locked up in the alginate beads
    means easy separation to produce lactose free milk
    Solution then pasteurised to kill micro-organisms
    tested with rezasurin to make sure all microbes are killed
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    (Original post by apk1)
    HOW IS LACTOSE-FREE MILK PRODUCED? (6 MARKS)

    - made using LACTASE
    - using EMBOLIZED enzymes
    - LACTASE converted into GALACTOSE and GLUCOSE
    - beneficial for people with LACTOSE INTOLERANCE

    Oh well I messed that up. I wrote that immobilised beads containing the enzyme lactase were put in milk, which broke down the sugars in milk - lactose - and made it lactose free. The beads were reusable and the milk can be drunk by people with lactose intolerance.


    Think ill get any marks?
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    HOW IS VEGETARIAN CHEESE PRODUCED? (4 MARKS)

    - made using CHYMOSIN
    - produced by GENETICALLY MODIFIED ORGANISMS
    - CHYMOSIN initiating CLOTTING
    - REDUCED use of RENNET (which is extracted from animals)
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    started a thread to get some organised answers as this is a little messy and confusing ! go comment answers and questions to help complete it
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    (Original post by Aaron jhooty)
    What about the last six marker? I mentioned sodium algninate solution with calcium chloride solution to form calcium Alginate with immobilised enzymes in there. I also said immobilised enzymes are enzymes trapped in or on an inert material. For the actual process I talked about how lactase is immobilised and converts lactose into galactose and fructose, and this makes sure those who don't naturally produce the enzyme lactase don't become unwell when drinking the lactose free milk
    Immobilise the lactase mixing sodium alginate and lactase together in a syringe, add the mixture one drop at a time into calcium chloride, the beads form, leave them to harden for a few minutes then separate them from the calcium chloride solution. Put nylon gauze in a syringe and attach a tap to the end, add the beads to the syringe. Use a glucose test-strip to test for glucose present in a breaker of milk. Add milk to the syringe; collect the treated milk in a small beaker. Test the glucose content of the treated milk and compare it to the untreated milk using a glucose test-strip, the colour will change in the treated milk showing lactose has been converted to glucose.
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    (Original post by oliver45456)
    and the lactase breaks down lactose into lactic acid
    Sodium alginate beads dropped into calcium chloride solution
    Lactic acid was locked up in the alginate beads
    means easy separation to produce lactose free milk
    Solution then pasteurised to kill micro-organisms
    tested with rezasurin to make sure all microbes are killed
    lactase breaking down into lactic acid is for yogurt production
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    (Original post by Amelia Louise)
    Oh well I messed that up. I wrote that immobilised beads containing the enzyme lactase were put in milk, which broke down the sugars in milk - lactose - and made it lactose free. The beads were reusable and the milk can be drunk by people with lactose intolerance.


    Think ill get any marks?
    yh sure. my answer is what I found on a mark scheme for an old test paper.
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    It's not option D, it was both species that could pollinate it.
    (Original post by dd897)
    Here is the long awaited markscheme. I think the grade boundaries will be pretty low but overall I think personally I did okay – Please remember you can bring up your grade with the other exams and don’t worry if you get wrong answers! Feel free to add to the markscheme below as I can’t remember all the questions. Good luck!

    1a. Species 1 because the nectar is at the top

    1b. Option D

    1c. Co-evolution: As one species evolves the other devolves so moth becomes deformed so its proboscis shrinks so co-evolution benefits the orchid, not the moth

    2a. Dominant allele = Male Recessive allele = Female OR Isotope monitor

    Classical conditioning

    Put a flag in front of horse to habituate it

    38 HIV

    Vegetarian cheese à use restriction enzyme to combine milk together to make it yellow and clot to form cheese and then put it into a fermenter

    Lactose free-milk à Normal milk + sieve + barium nitrate, so lactose is extracted. Include conditions of pH, temperature and contamination
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    (Original post by apk1)
    yh sure. my answer is what I found on a mark scheme for an old test paper.
    Could you send me the mark scheme with all the marks please? Do you know how many i would get?
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    (Original post by Aaron jhooty)
    I wouldn't be surprised if both 48 and 24 are accepted, the question was not the best worded.
    It was worded perfectly and made very clearly that it was 16000 people to be split into two groups. Only 24 will be accepted.
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    (Original post by apk1)
    lactase breaking down into lactic acid is for yogurt production
    Luckily you don't get negatively marked so it should be fine. anyway the other pints are all valid
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    (Original post by milesdavis)
    what do you guys predict the grade boundary to be?
    I predict 53-54 as it was quite an easy paper
 
 
 
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