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    I thought I'd make an unofficial mark scheme for the exam. Feel free to help me make it

    I found it very difficult and challenging - how did you find it?
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    So difficult!
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    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 decrease as the concentration gradient will be smaller / stomata will not open as the guard cells are less likely to become turgid and open

    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]
    example
    ring width increase may have had other factors, not just temperature (1)
    cannot be proven as this is just one scenario (1)

    two marks may be awarded if a correct evaluation is done

    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

    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]
    Marking points
    how blood clots: platelets come in contact with damaged blood vessels, causing a series of chemical reactions leading to the formation of a mesh of fibrin fibres (clot)

    aspirin and warfarin are anti-coagulants and so control clotting, but increase the risk of bleeding

    aspirin: stops platelet production and so reduces clotting (as seen in graph) as the platelets cannot collect at the damaged vessel, meaning that they are less likely to cause a blockage - however, as seen in the graph, this does lead to the issue that there is a higher incidence of dangerous bleeding

    warfarin: reduces fibrin and so the platelets are less reinforced and are more likely to be swept away by the blood, leading to the lower amount of dangerous clotting, as seen in the graph - however , also as seen in the graph, this will lead to the issue of dangerous bleeding as the platelets may be swept away, causing bleeding

    why he should take one of them: so that his risk of dangerous blood clots is reduced, do that he doesn't need more surgery

    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)

    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]
    any two of
    villi (and microvilli) having a large surface area and good blood supply (1)
    long so that there is high chance for absorption (1)
    excellent blood supply (1)
    thin permeable wall (1)

    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 between two graphs in two different areas, suggesting reasons for these [6]
    similarities: predator-prey relationship in both, with explanation why it is out of phase, to include phytoplankton being the prey/producers, and the zooplankton being the predators/consumers

    differences: phytoplankton increased in numbers in an earlier time of the year in the first graph, in comparison to the second graph - indicating that, earlier in the year, the first graph's area is warmer and sunnier than the second graph's area, as the phytoplankton would thus be able to photosynthesise more and increase in numbers

    9. Biogas
    a) Give two advantages of biomethane, and one disadvantage [3]
    advantages - any two of
    more energy released than landfill gas (1)
    high methane concentration - not explosive (1)
    less CO2 produced (1)
    'cleaner' (1)

    disadvantage - any one of
    requires energy to make from landfill gas (remove CO2) (1)
    there may be other suitable examples

    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)

    -----------------

    there are two interpretations of this question and so both are included

    c) Explain why the temperature is reduced below 50°C but above 35°C when 50°C gives best rate of reaction [2]
    (compromise between) need for high rate of fermentation (1)
    (and) the cost incurred by maintaining a high temperature (1)

    or

    c) Explain why the temperature is not above 50°C or below 35°C [2]
    (compromise between) need for high rate of fermentation (1)
    (and) the cost incurred by maintaining a high temperature (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 / observations matching predictions (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)
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    (Original post by robyn2000)
    So difficult!
    It's the hardest paper I've sat
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    I've started making one but it's incomplete. You can use my answers if you like.
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    (Original post by Wolfram Alpha)
    I've started making one but it's incomplete. You can use my answers if you like.
    Ok, thanks very much
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    (Original post by some-student)
    OCR Gateway Biology B
    P4 P5 P6 + Section D Exam
    Friday 17th July 2016
    Unofficial Mark Scheme

    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]
    .......

    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)
    I got these but instead of plasmolysed is said flaccid.. Would both be accepted?

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    (Original post by leopard923)
    I got these but instead of plasmolysed is said flaccid.. Would both be accepted?

    Posted from TSR Mobile
    No, only plasmolysed would be accepted.
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    -6.25% for the percentage change question?
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    (Original post by leopard923)
    I got these but instead of plasmolysed is said flaccid.. Would both be accepted?

    Posted from TSR Mobile
    I found an image on Google and it seems to show that flaccid is different from plasmolysed... but I'm not too sure

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    (Original post by robyn2000)
    -6.25% for the percentage change question?
    Yes, but I rounded mine to -6.3% and now I'm worried
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    (Original post by some-student)
    I found an image on Google and it seems to show that flaccid is different from plasmolysed... but I'm not too sure

    Ok thank you

    Posted from TSR Mobile
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    (Original post by maxthomas2610)
    What were the four proteins?
    oxygen nitrogen hydrogen carbon
    I didn't put this, I guessed! I looked it up
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    B6

    1. 50 degrees and ph5

    2. 55 degrees is better than 60 because less energy required to heat to that temperature and there is less of a decrease in activity should ph change slightly

    3. Advantage of free enzyme is the rate of reaction is higher
    Advantage of immobilised enzyme is it is easier to separate from the mixture

    4. Glucose and fructose are sweeter so less sugar needed for same sweetness so more products can be made using the same amount of sugar. Also low calorie foods can be made

    5. Phytoplankton and zooplankton graphs:
    Explanation- summer months more light and temperature so more photosynthesis and so more food for zooplankton - decrease because phytoplankton get eaten and then zooplankton starve

    6. Biomethane - advantage - less co2 produced and more energy released
    Disadvantage - costs money to remove co2 whereas natural gas could be used

    7. Waterlogged soil displaces oxygen so more anaerobic respiration occurs so more landfill gas produced

    8. Must be monitored because of methane falls below 10% it becomes explosive

    Can't remember any more
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    B6:

    50 degrees c and pH 5

    The curve for 55 degrees is more
    gradual/smoother so any fluctuation in temp would have less of an effect on rate of reaction than 60 degrees would.

    Advantages of immobilised enzyme: doesn't contaminate substance, can be reused etc
    Advantages of free enzyme: activity rate is nearly four times faster.

    Biomethane advantages: lower carbon dioxide content, higher methane content so less explosive, more readily available than natural gas (possibly, I just guessed that one)
    Disadvantage: the process of removing the carbon dioxide and other gases may be expensive or involve harsh conditions.

    Have to keep monitoring the has levels as if the methane level drops too low it could be dangerous/explosive.

    Phytoplankton/zooplankton 6 marker:
    Similarities - the biomass of zooplankton peaks just after that of phytoplankton on both graphs.
    Differences - phytoplankton biomass increases in the summer in the Arctic as it is lightest and warmest so they can photosynthesise and grow more and provide more food for zooplankton. In the North Atlantic biomass is high in spring as it is further south so population is higher in the warmer weather and by the end of summer, the nutrients start to run out reducing numbers. (Kinda guessed this so don't take my word for it).

    Can't remember what else is was in B6 or the question numbers/number of marks.
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    (Original post by roxy100)
    B6

    1. 50 degrees and ph5

    2. 55 degrees is better than 60 because less energy required to heat to that temperature and there is less of a decrease in activity should ph change slightly

    3. Advantage of free enzyme is the rate of reaction is higher
    Advantage of immobilised enzyme is it is easier to separate from the mixture

    4. Glucose and fructose are sweeter so less sugar needed for same sweetness so more products can be made using the same amount of sugar. Also low calorie foods can be made

    5. Phytoplankton and zooplankton graphs:
    Explanation- summer months more light and temperature so more photosynthesis and so more food for zooplankton - decrease because phytoplankton get eaten and then zooplankton starve

    6. Biomethane - advantage - less co2 produced and more energy released
    Disadvantage - costs money to remove co2 whereas natural gas could be used

    7. Waterlogged soil displaces oxygen so more anaerobic respiration occurs so more landfill gas produced

    8. Must be monitored because of methane falls below 10% it becomes explosive

    Can't remember any more
    Sorry didn't realise you posted this while I was typing mine up!
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    Was this paper harder than usual for you guys? Do you think perhaps the grade boundaries will be lower for this paper?
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    (Original post by roxy100)
    B6

    1. 50 degrees and ph5

    2. 55 degrees is better than 60 because less energy required to heat to that temperature and there is less of a decrease in activity should ph change slightly

    3. Advantage of free enzyme is the rate of reaction is higher
    Advantage of immobilised enzyme is it is easier to separate from the mixture

    4. Glucose and fructose are sweeter so less sugar needed for same sweetness so more products can be made using the same amount of sugar. Also low calorie foods can be made

    5. Phytoplankton and zooplankton graphs:
    Explanation- summer months more light and temperature so more photosynthesis and so more food for zooplankton - decrease because phytoplankton get eaten and then zooplankton starve

    6. Biomethane - advantage - less co2 produced and more energy released
    Disadvantage - costs money to remove co2 whereas natural gas could be used

    7. Waterlogged soil displaces oxygen so more anaerobic respiration occurs so more landfill gas produced

    8. Must be monitored because of methane falls below 10% it becomes explosive

    Can't remember any more
    (Original post by yellowgiraffe28)
    B6:

    50 degrees c and pH 5

    The curve for 55 degrees is more
    gradual/smoother so any fluctuation in temp would have less of an effect on rate of reaction than 60 degrees would.

    Advantages of immobilised enzyme: doesn't contaminate substance, can be reused etc
    Advantages of free enzyme: activity rate is nearly four times faster.

    Biomethane advantages: lower carbon dioxide content, higher methane content so less explosive, more readily available than natural gas (possibly, I just guessed that one)
    Disadvantage: the process of removing the carbon dioxide and other gases may be expensive or involve harsh conditions.

    Have to keep monitoring the has levels as if the methane level drops too low it could be dangerous/explosive.

    Phytoplankton/zooplankton 6 marker:
    Similarities - the biomass of zooplankton peaks just after that of phytoplankton on both graphs.
    Differences - phytoplankton biomass increases in the summer in the Arctic as it is lightest and warmest so they can photosynthesise and grow more and provide more food for zooplankton. In the North Atlantic biomass is high in spring as it is further south so population is higher in the warmer weather and by the end of summer, the nutrients start to run out reducing numbers. (Kinda guessed this so don't take my word for it).

    Can't remember what else is was in B6 or the question numbers/number of marks.
    Thanks both - I will add them into my markscheme
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    (Original post by davist)
    Was this paper harder than usual for you guys? Do you think perhaps the grade boundaries will be lower for this paper?
    I definitely found it harder, but I don't know about the grade boundaries though
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    (Original post by davist)
    Was this paper harder than usual for you guys? Do you think perhaps the grade boundaries will be lower for this paper?
    They will be higher than b1b2b3 because the skills section was with it

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