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AQA GCSE Biology Unit 2 - 24th January 2012 Unofficial Markscheme

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    (Original post by Wintabix)
    Yeah but plant can respire as well when they are not photosynthesising
    Fair point, but that question was again bad.
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    (Original post by lg2012)
    for the diabetes/ insulin q

    i put A

    becuase the side effect for A was weight loss, and the q was asking about low blood sugar

    i thought that because the side effect for insulin (which is for high blood sugar) was weight gain and low blood sugar is the opposite.

    I put that the fat store of gycogen was converted back to glucose which results in weight loss

    can someone tell me if i just wrote rubbish or if what i wrote was right ?? x

    also for the one describing the enzyme table i like described it saying that the one with boiling crushed apple was the highest etc... was that wrong ?? x
    ye i totally agree with you. I put A because:
    1) weight loss- the glucose can't be stored so it is excreted. Therefore, any fats/muscles in the body are broken down into glucose so they can be used for energy by respiration. This results in a weight loss.
    2) damage to liver, kidneys and pancreas- All these muscles contain glycogen stores, and the muscle is broken down for respiration. This is turn damages the organs as they are worn away.
    3) feeling ill- the person would feel ill as they have a lack of glucose for respiration and are extremely weak as their biomass is being used for respiration. Furthermore, they would feel lethargic.

    i have no idea if its right but it makes more sense to me than the other options. correct me if i'm wrong

    Oh and another correction... I'm sorry to leave a lot of you disappointed but the correct answer was actually 5 minutes for the frostbit question...WHY? well, at 10 minutes it's kind of obvious the person would have hypothermia at this time so 10 minutes isn't safe. a lot of people said 9 but this is actually wrong as there is no data to say 9 minutes is safe. the intervals go from 5 to 10. therefore, hypothermia could happen at any time between these two figures e.g. 6 minutes

    so basically the only guaranteed safe time is 5 minutes (btw i didnt actually write this, because i am a comlete clutz and only after did i actually understand it!)
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    Do you think 'Decay' will be accepted for the {roughly}, "In what form will the grass' energy be lost?"...I doubt it...
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    (Original post by Thames)
    ye i totally agree with you. I put A because:
    1) weight loss- the glucose can't be stored so it is excreted. Therefore, any fats/muscles in the body are broken down into glucose so they can be used for energy by respiration. This results in a weight loss.
    2) damage to liver, kidneys and pancreas- All these muscles contain glycogen stores, and the muscle is broken down for respiration. This is turn damages the organs as they are worn away.
    3) feeling ill- the person would feel ill as they have a lack of glucose for respiration and are extremely weak as their biomass is being used for respiration. Furthermore, they would feel lethargic.

    i have no idea if its right but it makes more sense to me than the other options. correct me if i'm wrong

    Oh and another correction... I'm sorry to leave a lot of you disappointed but the correct answer was actually 5 minutes for the frostbit question...WHY? well, at 10 minutes it's kind of obvious the person would have hypothermia at this time so 10 minutes isn't safe. a lot of people said 9 but this is actually wrong as there is no data to say 9 minutes is safe. the intervals go from 5 to 10. therefore, hypothermia could happen at any time between these two figures e.g. 6 minutes

    so basically the only guaranteed safe time is 5 minutes (btw i didnt actually write this, because i am a comlete clutz and only after did i actually understand it!)
    In the Real world maybe, but the question never mentioned Hypothermia.
    Then again.. the rest of them were worded awfully....

    I reckon theyll allow anywhere between 5 and 10 minutes. or atleast thats what the general consensus seems to be.
    I put 9 though, and believe that to be the correct answer.
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    what do you think the grade boundaries will be roughly judging on how hard the paper was?
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    (Original post by Math12345)
    AQA GCSE Biology Unit 2 Unofficial Markscheme


    1.
    a. As you decrease the temperature the time taken to get the frostbite decreases (or you get frostbite more quickly). (1)
    b. 9 or 10 minutes. (1) This was confusing, because it could be anywhere between 9 and 10.
    c. Shivering and constriction. (2)

    2.
    a. Control variables: mass of crushed apple / amount of drops of liquid. (1) There are more possibilities.
    b. The drops can be different sizes. (1)
    c. Amylase does not break down the cell wall like water. Pectinase enzyme digests the cell wall. Energy in boiling water causes the cell wall to break apart. (3) Improvement?
    d.
    i. 11.6 cm^3 (1) Not sure...
    ii. Pectinase enzyme is denatured at high temperatures, but boiling the apple still has the same effect. (2) Improvement?

    3.
    a. Drug B - Kills pancreatic cells which means even less insulin is produced than before (which is why it only has negative effect on some diabetics). (2) Improvement?
    b) Careful attention to diet and pancreatic cell transplants (2) There are more possibilities.
    c) The insulin enzymes are destroyed by the digestive system or The insulin in the tablet would not reach the blood (1) I am sure there are many other possible things you could have write

    4.
    a. Cloudy means less light so less photosynthesis so less CO2 used. (2) Improvement?
    b. Magnesium. (1)

    5.
    a. (45/25,000)*100=0.18% (2)
    b) Heat. (1)
    c) Shorter food chains more efficient as there are less energy losses. Heron only gets 2 out of the 25,000kJ of energy absorbed. (2) Improvement?
    d) Microorganisms consume the dead animals and plants causing decay. They then used the biomass for respiration which released carbon dioxide into the atmosphere - replacing CO2. CO2 then used in photosynthesis to be returned to the food chain. (3) Improvement?

    6
    a. Water moves through the partially permeable membrane by osmosis from the dilute solution to the more concentrated sugar solution causing the solution level to rise. (3) Improvement?
    b) Would still increase, but at a slower rate the solution is less concentrated so smaller concentration gradient. (1) Improvement?

    7
    a.
    i. Gene. (1)
    ii. Ribosomes. (1)
    b) A combination of three bases codes for different amino acids. Amino acids then join together to create the protein which codes for blue eyes. (3) Improvement?
    c) Different amino acids in structure. (1) Not sure...
    ii) Different coloured eyes. (1) Not sure...

    8. (5)
    Adult bone marrow - Advantages
    Does not kill embryos (1)
    It is a simple operation (1)
    Can still cure heart and blood diseases (1)

    Adult bone marrow - Disadvantages


    Embryonic stem cells - Advantages
    Is not painful to patient (1)
    Can develop into any type of cell so can cure more diseases (1)

    Embryonic stem cells - Disadvantages

    Conclusion (1)
    You missed out 3C
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    After looking at the unofficial markscheme, i get around 17 if I am harsh on myself.. and 23 if i am generous.

    So lets take my average as 20.. can anyone give me a rough idea of what grade I may get?
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    (Original post by lg2012)
    for the diabetes/ insulin q

    i put A

    becuase the side effect for A was weight loss, and the q was asking about low blood sugar

    i thought that because the side effect for insulin (which is for high blood sugar) was weight gain and low blood sugar is the opposite.

    I put that the fat store of gycogen was converted back to glucose which results in weight loss

    can someone tell me if i just wrote rubbish or if what i wrote was right ?? x

    also for the one describing the enzyme table i like described it saying that the one with boiling crushed apple was the highest etc... was that wrong ?? x
    omg i put A and for the exact same reason!!! just hope its right!
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    What was the actual question for 3a about the drugs A,B,C,D I have and awful feeling I've got completely the wrong idea :/
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    for the one about how to control the amount of glucose in blood, i wrote inject insulin and have a low starch diet.... i know the injecting one was wrong because we were supposed to give two different solutions but hope the second one was right!
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    (Original post by alex321)
    What was the actual question for 3a about the drugs A,B,C,D I have and awful feeling I've got completely the wrong idea :/
    There was so many different possibilities of answers. As long as you have properly justified your answer and not just blabbered. You'll be all right.

    You should worry if your answer contradicts or doesn't add up to the information provided in the boxes.
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    (Original post by MattDowse)
    After looking at the unofficial markscheme, i get around 17 if I am harsh on myself.. and 23 if i am generous.

    So lets take my average as 20.. can anyone give me a rough idea of what grade I may get?
    My guess is a good B like 76% but I bet you actually did better than you think!
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    (Original post by Zaii786)
    for the one about how to control the amount of glucose in blood, i wrote inject insulin and have a low starch diet.... i know the injecting one was wrong because we were supposed to give two different solutions but hope the second one was right!
    What did the question specifically ask? Was it for a treatment/cure? Or ways it can be monitored/prevented.

    Yeah, I put insulin injections too. Sucks mate.

    I put pancreas transplant, hopefully thats right.
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    (Original post by sabrina_96)
    what do you think the grade boundaries will be roughly judging on how hard the paper was?

    I reckon 22-27 marks for an A. Most people I have spoken with at school said they'd dropped 5 marks on the bases question about how it is constructed.
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    (Original post by StateSchooler95)
    What did the question specifically ask? Was it for a treatment/cure? Or ways it can be monitored/prevented.

    Yeah, I put insulin injections too. Sucks mate.

    I put pancreas transplant, hopefully thats right.
    The transplant is 100% correct. What do you reckon to Exercise-it is mentioned in revision guides?
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    for the June 2011 B2 paper the grade boundaries were:
    A*- 26, A -23, B- 18, C -13
    It's obviously my personal opinion, but i'd say that today's exam was harder (i did the June one as a mock), so hopefully grade boundaries will be a little lower
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    (Original post by Math12345)
    AQA GCSE Biology Unit 2 Unofficial Markscheme



    c. Amylase does not break down the cell wall like water. Pectinase enzyme digests the cell wall. Energy in boiling water causes the cell wall to break apart. (3) Improvement?
    Can anyone remember or tell me what this question was about.
    I think I may have have missed it in the paper. Another 3 marks down the drain.
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    (Original post by StateSchooler95)
    There was so many different possibilities of answers. As long as you have properly justified your answer and not just blabbered. You'll be all right.

    You should worry if your answer contradicts or doesn't add up to the information provided in the boxes.
    Thanks!
    Hmmm, hopefully! I said something about how they'll eat more due to weight loss so there'll be more glucose in the blood? Pretty annoying! :P
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    (Original post by StateSchooler95)
    Can anyone remember or tell me what this question was about.
    I think I may have have missed it in the paper. Another 3 marks down the drain.
    About the fruit juice - boiled apple.....
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    (Original post by gabe_96)
    for the June 2011 B2 paper the grade boundaries were:
    A*- 26, A -23, B- 18, C -13
    It's obviously my personal opinion, but i'd say that today's exam was harder (i did the June one as a mock), so hopefully grade boundaries will be a little lower
    Yeah it was. But to be fair, if the question about bases and how they constructed amino acids had not come up, and instead there was a question about Huntington's disease/cystic fibrosis I reckon people would have classed this as a easier exam.

    Lets face it, AQA did their research and included that question by purpose.

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