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    Does anyone know what the 6 markers required you to write?
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    b) Explain why the same enzyme should be used to cut the DNA [2]
    I think your answer may be incorrect. The correct answer is that there would be no complimentary base pairing meaning DNA ligase would not be able to repair the cut surfaces. I think...
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    (Original post by Wolfram Alpha)
    b) Explain why the same enzyme should be used to cut the DNA [2]
    I think your answer may be incorrect. The correct answer is that there would be no complimentary base pairing meaning DNA ligase would not be able to repair the cut surfaces. I think...
    Ok, thanks I wasn't really sure what the answer was so you're probably right. I'll replace my answer with your answer.
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    what are the grade boundaries normally like for a c n whatnot? ahh i can't find them.
    oops i thought it went alright until i saw this
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    In the past years, the grade boundaries have been as follows;
    2015- A*: 49, A: 41, B: 33, C: 25
    2014- A*: 53, A: 43, B: 33, C: 24
    2013- A*: 47, A: 39, B: 31, C: 23
    In comparison to these past papers, I believe that this paper was marginally more difficult, so I think that the grade boundaries will look something like this; A*: 48, A: 38, B: 32, C: 24.
    Hope that this helps some of you out! [Links: http://www.ocr.org.uk/i-want-to/conv...marks-to-ums/]
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    (Original post by some-student)
    Yes, but I rounded mine to -6.3% and now I'm worried
    The answer should be accepted. If it's not what they put in the answer section, it will be put in the guidance section of the mark scheme.
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    U see for how much the woman had to gain to be in low risk, does it have to be 8kg? Because the region was 70-75 wasn't it? And she weighed 67 so she only needed to gain 3 to fit in ?

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    (Original post by LieutenantJ)
    The answer should be accepted. If it's not what they put in the answer section, it will be put in the guidance section of the mark scheme.
    Great, thanks
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    (Original post by leopard923)
    U see for how much the woman had to gain to be in low risk, does it have to be 8kg? Because the region was 70-75 wasn't it? And she weighed 67 so she only needed to gain 3 to fit in ?

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    8kg was the minimum, it was 75 - something for low risk

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    (Original post by leopard923)
    U see for how much the woman had to gain to be in low risk, does it have to be 8kg? Because the region was 70-75 wasn't it? And she weighed 67 so she only needed to gain 3 to fit in ?

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    I seem to remember the region was 75-80, but I'm doubting myself now... You could be right though .
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    (Original post by some-student)
    I seem to remember the region was 75-80, but I'm doubting myself now... You could be right though .
    Maybe I read it wrong:eek: oh well

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    (Original post by some-student)
    OCR Gateway Biology B
    B4 B5 B6 + Section D Exam
    Friday 17th July 2016
    Unofficial Mark Scheme - 85 Marks

    MODULE B4: 25 MARKS
    1. Apple tree
    a) A tree is not watered for a month
    a)i) Pick the picture of the cell after no watering for a month [1]
    D (1)

    a)ii) Describe cell after no watering for a month [1]
    Plasmolysed (1)

    b) How would active transport work for minerals? [2]
    moving substances / mineralsagainst the concentration gradient (1)
    using energy from respiration (1)

    2. Methuselah the tree
    a) Explain how photosynthesis and transpiration are affected by: low temperature, dry soil, and strong wind [6]
    Marking points
    low temperature: limiting factor of photosynthesis (enzymes) and so photosynthesis will be slower; transpiration will decrease as the water molecules will have less energy to evaporate out of the stomata

    dry soil: less water for photosynthesis (reactant) and so photosynthesis will be slower; transpiration will increase as the concentration gradient will be maintained, further slowing photosynthesis

    strong wind: transpiration will increase as the concentration gradient will be maintained - water outside will be blown away, further slowing photosynthesis as there will be less water

    b) These trees have a resin that causes little water and oxygen absorption. Why would this stop the tee from rotting? [2]
    stops decomposers respiring (1)
    so they reproduce less / die (1)

    c) Name the cells that transport substances, and what they transport [4]
    xylem made of dead cells (1)
    transports water (1)
    phloem made of living cells (1)
    transports food / sugars (1)

    d) Ring width
    d)i) Using the graph, evaluate the the claim that ring width has increased [2]
    overall increase (1)
    but has been mostly decreasing and only recently quickly increased (1)

    d)ii) Evaluate the the claim that the data proves global warming [2]
    ring width increase may have had other factors, not just temperature (1)
    cannot be proven as this is just one scenario (1) [This may be subjective. As it asked you to evaluate the data, marks could be awarded if you wrote yes or no. I think that the marks would be more reliant on the explanation of your decision.]

    3. Pigments in plants
    a) Explain why red seaweed can live at the bottom of the sea (given a graph where red penetrates the least deep) [3]
    use of data (1)
    red seaweed absorb all of the light except red (1)
    so they can live as deep as the deepest pigment they absorb (green) (1)

    b) Name the four elements in a protein [2]
    all four (2)
    three (1)
    otherwise (0)

    carbon, hydrogen, oxygen, nitrogen [Not too sure if this is right, but I wrote amino acids as one of the elements..? It was a complete guess.]

    MODULE B5: 25 MARKS
    4. Bones
    a) Draw lines to show where the cartilage and bone marrow are in the femur [2]
    line connecting cartilage to dotted bit at top of bone (1)
    line connecting bone marrow to filled bit in middle of bone (1)

    b) Explain the two types of joint in the femur [2]
    ball and socket: full rotational movement (1)
    hinge: only in one direction (1)

    c) How many kg does she need to gain to be in the low risk category? [1]
    8kg (1)

    d) Explain why people over 45 may get a fracture if they have a fall [2]
    calcium is lost from bones (1)
    making them softer / more brittle (1)

    5. Blood/the heart
    a) What surgery would he need for a blocked coronary artery (tick one)? [1]
    by-pass surgery (1)

    b) Graph, aspirin, warfarin - how do they do what happens in the graph, and explain why he should take one [6]
    .....
    [An explanation of how blood clots would be needed. Warfarin and aspirin educed the chance of dangerous blood clots, though increased the chance of dangerous bleeding, as blood cannot clot (both are anti-coagulants). Use of the data shown in the graph may be necessary.]
    c) He has a blood type O. Tick one box to show which antibodies and antigens he has. [2]
    antibodies: anti-A and anti-B (1)
    antigens: none (1)

    d) Explain what would happen if he was transfused with A type blood. [2]
    anti-A antibodies would lock onto A antigens (1)
    agglutination (1) [Blood type O is a universal donor. I believe that a transfusion would work, as there are no antigens on the surface of the blood cell. There are, however, both antibodies A and B, which would suggest that agglutination would occur.]

    6. Running race
    a) Calculate Sanchez's percentage change and suggest who would win [2]
    (60 / 64 - 1) x 100 = -6.25%/-6.3% (1)
    Leroy, as he only is thirsty, while Sanchez is so dehydrated that he has muscle cramps and spasms (1)

    b) Explain how the small intestine is adapted for rapid absorption [2]
    villi (and microvilli) having a large surface area and good blood supply (1)
    long so that there is high chance for absorption (1) [A range of adaptations would be suitable here, such as the excellent blood supply, thin permeable wall, etc.]

    c) Explain why Leroy will produce more urine even though they drink the same amount [3]
    more water in blood stream as less dehydrated (1)
    less ADH released (1)
    kidneys tubules less permeable and less water absorbed into blood - instead goes into urine (1)

    MODULE B6: 25 MARKS
    7. Invertase and enzymes
    a) Using the graph, what are the ideal conditions for immobilised invertase? [1]
    pH of 5 and temperature of 50°C (1)

    b) On the graph, for free invertase, the rate for pH 5 + 55°C is the same as pH 5 + 60°C. Explain why 55°C is used [2]
    lower temperature and no effect on activity (1)
    any change in pH has a lesser effect as curve is smoother (1)

    c) Using the data and your knowledge, give one advantage of immobilised enzymes, and one disadvantage of free enzymes [2]
    do not contaminate product / continuous flow processing / easier to remove from mixture (1)
    free enzymes have a much higher activity rate (1)

    d) Explain why sucrose when broken down (sweeter) is beneficial to the food industry [2]
    foods can therefore be sweetened without adding so much sugar (1)
    e.g. in low calorie foods (1)

    8. Phytoplankton/zooplankton numbers : similarities/differences, suggesting reasons for these [6]
    .............................

    9. Biogas
    a) Give two advantages of biomethane, and one disadvantage [3]
    advantage: more energy released than landfill gas (1)
    advantage: high methane concentration - not explosive / less CO2 produced (1)
    disadvantage: requires energy to make from landfill gas (remove CO2) (1)
    [Once again, a range of answers may be acceptable.]
    b) Explain why more biogas will be produced in water-logged soils [2]
    less oxygen for the decomposers (1)
    therefore more anaerobic respiration producing more biogas (1)

    c) Explain why production rate may be affected outside of 35°C-50°C [2]
    below - enzyme function is slow (1)
    above - enzymes denatured (1)

    d) Explain why even after decommission, the landfill sites are monitored [1]
    about 10% is explosive (1)

    10. Genetic engineering
    a)i) The enzyme used to cut DNA [1]
    restriction enzyme (1)

    a)ii) The enzyme used to stick DNA [1]
    (DNA) ligase (1)

    b) Explain why the same enzyme should be used to cut the DNA [2]
    (there would be) no complimentary base pairing (1)
    (DNA) ligase would not be able to repair the cut surfaces / sticky ends (1)

    SECTION D: 10 MARKS
    11. Parakeets
    a) Given two surveys - explain if a trend could be seen [2]
    there is a change in number of sightings (1)
    but there wasn't any breeding before (1)

    b) "they like to live down south because of warm temperatures" [2]
    we don't know if the temperatures are the reason (1)
    they might just live there by chance / are moving up north (1)

    c)i) Year with most confidence [1]
    2005 (1)

    c)ii) Suggest why [1]
    more data collected (1)

    d)i) "numbers have been decreasing" [2]
    line for all species has actually gone up a tiny bit (1)
    the lines that are decreasing do not constitute half of the species in total (1)

    d)ii) Suggest why percentages are used rather than population sizes [2]
    population sizes are different for each species (1)
    percentage is standardised (1)
    Hope this helps!
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    (Original post by some-student)
    I seem to remember the region was 75-80, but I'm doubting myself now... You could be right though .
    I got 8kg too so i'm hoping that's right!
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    (Original post by mxskaan)
    I got 8kg too so i'm hoping that's right!
    8kg was correct. She weighed 67kg, which was, I believe, in the 'moderately unfit' (or words to that effect). To fit into the healthy bracket, she needed to be at least 75kg.
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    (Original post by mxskaan)
    I got 8kg too so i'm hoping that's right!
    It probably is I always make stupid mistakes:no:

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    (Original post by GCShElpme)
    Hope this helps!
    Brilliant, thank you - I will update my mark scheme
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    (Original post by some-student)
    Brilliant, thank you - I will update my mark scheme
    It's not a problem- thank you for creating such a great mark scheme! It really relieved me.
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    (Original post by GCShElpme)
    It's not a problem- thank you for creating such a great mark scheme! It really relieved me.
    Thanks
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    (Original post by GCShElpme)
    8kg was correct. She weighed 67kg, which was, I believe, in the 'moderately unfit' (or words to that effect). To fit into the healthy bracket, she needed to be at least 75kg.
    I put 10kg, would that still get me a mark?
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    Also guys, what do you think the grade boundaries would be like this year? Any estimates?
 
 
 
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