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AS Edexcel Biology Unit 1 June 12- 14th of May

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    (Original post by fifty_six)
    ADVICE needed..
    will i get a higher grade is i study the MS of every exam from2009 till 2012..
    Well that's what i'm planning to do right now

    Then i'm going to read through the textbook tonight
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    (Original post by oli_G)
    Well that's what i'm planning to do right now

    Then i'm going to read through the textbook tonight
    any other tips.. i made a bit of mess i the 3b paper so trying to make up the marks to get an A
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    anyone have any idea of topics likely to come up?
    maybe if they haven't come up for a long time?
    thanks
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    (Original post by fifty_six)
    any other tips.. i made a bit of mess i the 3b paper so trying to make up the marks to get an A
    Realise that even if the question looks alien it will be on an area that you have covered, but may be worded in a different way. For me, I sometimes over complicate an answer, so remember that there will be very simple questions (for the D/E grade candidates) that are simple but the marks are easily lost.

    For data analysis state the general correlation, describe any 'major' changes between the two variables QUOTING THE RANGE OF THE X VALUES WHEN THIS OCCURS and always do a calculation - such as finding the difference between two data points. Stating information off the graph is not enough for the mark.

    For the assesed practical question you need to write about 4-5 points on the method of the experiment. Mention some control variables and make sure you say about repeats etc Also try and write in a logical and systematic way, as these questions are often where the quality of written communication is assessed.

    Lastly, be specific with your answers and try not to 'waffle' - i am prone to doing this. Don't think that you have to use up all the space. From what i've seen you can normally answer most of the marking points in about a third of the space.

    Good luck
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    (Original post by oli_G)
    Realise that even if the question looks alien it will be on an area that you have covered, but may be worded in a different way. For me, I sometimes over complicate an answer, so remember that there will be very simple questions (for the D/E grade candidates) that are simple but the marks are easily lost.

    For data analysis state the general correlation, describe any 'major' changes between the two variables QUOTING THE RANGE OF THE X VALUES WHEN THIS OCCURS and always do a calculation - such as finding the difference between two data points. Stating information off the graph is not enough for the mark.

    For the assesed practical question you need to write about 4-5 points on the method of the experiment. Mention some control variables and make sure you say about repeats etc Also try and write in a logical and systematic way, as these questions are often where the quality of written communication is assessed.

    Lastly, be specific with your answers and try not to 'waffle' - i am prone to doing this. Don't think that you have to use up all the space. From what
    i've seen you can normally answer most of the marking points in about a third of the space.

    Good luck
    thanks alot that really helped. i hope its an easy exam
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    hi guys, i feel pretty confident with the content but im absolutely ****e on the math questions :|
    could you give me percentage increase /decrease or whatever usual formulas that are needed in the exam?
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    Percent change =[ (new value - old value) / Old value ] * 100
    You subtract old value from new value and divide that by the old value. Then you multiply by hundred. If the answer is negative, it's a percentage decrease, if it's positive it's an increase.
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    (Original post by MBSSA)
    hi guys, i feel pretty confident with the content but im absolutely ****e on the math questions :|
    could you give me percentage increase /decrease or whatever usual formulas that are needed in the exam?
    Well the important thing to note that for percentage increase or decrease you do the change divided by the original amount.

    So, if the amount of dogs in a kennel goes from 20 to 25 the percentage increase is

    \frac{25-20}{20} \times 100

    Also remember to give to a suitable number of significant figures (like 3).
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    thanks for the help! good luck for tomorrow!
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    Can someone give me the model answer for how CF affects gas exchange? (5 marker )
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    Hi, need some help. can we give more than 2 answers when the question clearly state give 1? just curious. would there be any deduction if one of the alternative is wrong. thx
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    (Original post by GodIsMe)
    Can someone give me the model answer for how CF affects gas exchange? (5 marker )
    1. Cilia can't move the thick sticky mucus towards the throat, so it builds up and blocks airways
    2. If alveoli are blocked, gases cannot diffuse through properly
    3.Surface area for gas exchange is reduced as some alveoli are blocked, therefore sufferer will have breathing difficulties
    4. Lung infections may occur, as throat cannot move the thick, sticky mucus towards the throat and therefore, cannot get rid of infections trapped there. (This isn't really related to gas exchange very much, but just in case )

    Straight from the revision guide and textbook, although I'm not sure where the mark scheme would award you marks, specifically.
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    (Original post by Hootie*)
    1. Cilia can't move the thick sticky mucus towards the throat, so it builds up and blocks airways
    2. If alveoli are blocked, gases cannot diffuse through properly
    3.Surface area for gas exchange is reduced as some alveoli are blocked, therefore sufferer will have breathing difficulties
    4. Lung infections may occur, as throat cannot move the thick, sticky mucus towards the throat and therefore, cannot get rid of infections trapped there.

    Straight from the revision guide and textbook
    Cheers! :thumbsup:
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    (Original post by KHARTHIKD)
    Hi, need some help. can we give more than 2 answers when the question clearly state give 1? just curious. would there be any deduction if one of the alternative is wrong. thx
    I haven't really seen any mark schemes where they said CON if more than one answer given,(Unless it's for multiple choice questions!) but it may still be risky to do so. Try and incorporate the two answers into one, flowing sentence, so it isn't as obvious. No bullet points, really
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    (Original post by oli_G)
    Well the important thing to note that for percentage increase or decrease you do the change divided by the original amount.

    So, if the amount of dogs in a kennel goes from 20 to 25 the percentage increase is

    \frac{25-20}{25} \times 100

    Also remember to give to a suitable number of significant figures (like 3).
    would it not be 5/20 not 5/25 if it's the change divided by the original amount?
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    (Original post by GodIsMe)
    Can someone give me the model answer for how CF affects gas exchange? (5 marker )
    I would always start off by saying about the CFTR channel, therefore:

    1. In a CF sufferer, the CFTR channel is missing or non functional

    2. Na+ move into the epithelial cell and cannot move back out, causing water to be drawn from the surrounding mucus by the process of osmosis.

    3. This causes the mucus to become sticky.

    4. Beating ciliae struggle to move the mucus out of the lung because it's too sticky, causing it to remain in the lungs, trapping bacteria and blocking alveoli.

    5. Therefore less alveoli are available for gas exchange and so less oxygen is taken into the lungs.

    Hope this is enough for 5 marks!!
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    (Original post by bertiejess)
    would it not be 5/20 not 5/25 if it's the change divided by the original amount?
    Yeah, it should be. You just have to work out that difference, then find that as a % of the original value. So 5/20 x 100 = 25% increase.
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    You know how on the papers it says "pigment cannot leak out of the beetroot cells", apart from being released when the cell is damaged during cutting, how does it get out? :confused:
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    (Original post by bertiejess)
    I would always start off by saying about the CFTR channel, therefore:

    1. In a CF sufferer, the CFTR channel is missing or non functional

    2. Na+ move into the epithelial cell and cannot move back out, causing water to be drawn from the surrounding mucus by the process of osmosis.

    3. This causes the mucus to become sticky.

    4. Beating ciliae struggle to move the mucus out of the lung because it's too sticky, causing it to remain in the lungs, trapping bacteria and blocking alveoli.

    5. Therefore less alveoli are available for gas exchange and so less oxygen is taken into the lungs.

    Hope this is enough for 5 marks!!

    (Original post by GodIsMe)
    Cheers! :thumbsup:
    Yeah, I think Bertiejess' answer is more thorough than mine as she mention the cause of the cystic fibrosis, while I went straight for the effects. If you use her answer, at least you'll be assured that it's all there
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    Alcohol and temperature increase cell membrane permeability. Alcohol because it dissolves the lipids of the phospholipid bilayer and the membrane loses its structure, iirc

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