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    (Original post by tateco)
    The one about cell membranes was nothing to do with apoplast and symplast pathway, the way the worded it was to catch people out. You were supposed to talk about that water molecules are small enough to move through the phosopholipid bilayer passively by simple diffusion and it does not require transporter proteins or ATP...

    Great News!!
    I wrote Osmosis which should then be right!!
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    I loved the haemoglobin question though, easy marks in the bag there
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    ouch! that was not a good exam! i prefferred all the practices way more the grade bounderies better be low
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    (Original post by Study Buddy)

    Great News!!
    I wrote Osmosis which should then be right!!
    I agree with tateco... Got nothing to do with Symplast/Apoplast
    You have to say that water is polar so it diffuses through facilitated diffusion via aqua porins/ channel proteins
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    (Original post by Jessica.Jane23)
    ouch! that was not a good exam! i prefferred all the practices way more the grade bounderies better be low
    I doubt it will be low.. I think t'was a very easy paper. Only exception is the flower one
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    What did you put down for the question about histamine?
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    (Original post by adilh301)
    question: Describe the routes water takes across the cell surface membrane (2 marks).
    Answer: it travels via osmosis because it can diffuse through without touching the lipid tails one route if you even call it a route.
    Answer 2: it takes the symplast and vacuolar pathways with explanation two clear pathways of water molecules moving across membranes.
    this question was so easy because it was practically taken from the book.
    Page 73. OCR text book.
    How does water move between cells?
    When plant cells are touching each other molecules can pass from one cell to another. the water molecules will move from the cell with a higher water potential to the cell with the lower water potential.
    if that were the question then YEP osmosis is 100% correct and defining the mechanism of osmosis would probably score the second mark.
    What ROUTE can water take between cells?- sound familiar?
    The apoplast pathway
    The symplast pathway
    The vacuolar pathway
    symplast and vacuolar pathways both go across the cell surface membrane and are two different routes. which sounds more closely related to the question than simply the mechanism of osmosis.
    The pathways are not limited to root/endodermis cells as some people state it and if you want to see this for yourself look at the book alarm bells should have been ringing when you specified one route in a question that stated "routes" but yeah you'll probably reply with some flawed argument that i wont be bothered to reply to no offence , but it IS only 2 marks and osmosis could score you one mark.
    friends of mine who wrote osmosis now accept it as a mistake jheeze stop trying to justify 2 marks god i hate grey areas -.-
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    (Original post by adilh301)
    question: Describe the routes water takes across the cell surface membrane (2 marks).
    Answer: it travels via osmosis because it can diffuse through without touching the lipid tails one route if you even call it a route.
    Answer 2: it takes the symplast and vacuolar pathways with explanation two clear pathways of water molecules moving across membranes.
    this question was so easy because it was practically taken from the book.
    Page 73. OCR text book.
    How does water move between cells?
    When plant cells are touching each other molecules can pass from one cell to another. the water molecules will move from the cell with a higher water potential to the cell with the lower water potential.
    if that were the question then YEP osmosis is 100% correct and defining the mechanism of osmosis would probably score the second mark.
    What ROUTE can water take between cells?- sound familiar?
    The apoplast pathway
    The symplast pathway
    The vacuolar pathway
    symplast and vacuolar pathways both go across the cell surface membrane and are two different routes. which sounds more closely related to the question than simply the mechanism of osmosis.
    The pathways are not limited to root/endodermis cells as some people state it and if you want to see this for yourself look at the book alarm bells should have been ringing when you specified one route in a question that stated "routes" but yeah you'll probably reply with some flawed argument that i wont be bothered to reply to no offence , but it IS only 2 marks and osmosis could score you one mark.

    Soz mate, you've got it wrong. My biology teacher (must be the best in the country, predicted absolutely everything right on the paper, one of the questions word-for-word), said the following;

    One mark for plain diffusion/osmosis through the cell membrane, as water molecules are very small. However, the second mark, will be for mentioning channel proteins, as water molecules, however small, are actually charged, and so a channel protein lets through molecules that are charged. Remember that the Phosphate heads are actually hydrophobic, and that there is a chance that a water molecule could hit that and be repelled. As a result, there are channel proteins that open for water molecules to leave.

    The apoplast and symplast pathways are irrelevant to the cell surface membrane. They are relevant to how water, taken in at the roots, reaches the xylem cells.

    As it happens, I only got the first mark, but think about it, they cannot expect you to explain the apoplastic and symplastic pathways, as well as an explanation of diffusion in two lines and two marks. Even if you somehow managed to fit it in, it is irrelevant because nowhere in the question does it mention that. It mentions cell surface membrane, ie, the plasma membrane, not the symplastic and apoplastic pathways, which go through a number of cells, membranes and plasmodesmata.
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    quick question...

    if it asks for 2 reasons and you put 4-5....

    will the first 2 be marked and the rest ignored, or will all 5 be marked, so reason 1 and 4 are correct you get 2 marks out of 2
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    (Original post by Study Buddy)
    What did you put down for the question about histamine?
    Cell signalling

    Shape is complimentary to the active site on the glycoprotein activates second messenger molecule to bring about a change....
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    Allow this paper.
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    (Original post by DonFahad)
    Soz mate, you've got it wrong. My biology teacher (must be the best in the country, predicted absolutely everything right on the paper, one of the questions word-for-word), said the following;

    One mark for plain diffusion/osmosis through the cell membrane, as water molecules are very small. However, the second mark, will be for mentioning channel proteins, as water molecules, however small, are actually charged, and so a channel protein lets through molecules that are charged. Remember that the Phosphate heads are actually hydrophobic, and that there is a chance that a water molecule could hit that and be repelled. As a result, there are channel proteins that open for water molecules to leave.

    The apoplast and symplast pathways are irrelevant to the cell surface membrane. They are relevant to how water, taken in at the roots, reaches the xylem cells.

    As it happens, I only got the first mark, but think about it, they cannot expect you to explain the apoplastic and symplastic pathways, as well as an explanation of diffusion in two lines and two marks. Even if you somehow managed to fit it in, it is irrelevant because nowhere in the question does it mention that. It mentions cell surface membrane, ie, the plasma membrane, not the symplastic and apoplastic pathways, which go through a number of cells, membranes and plasmodesmata.
    Agreed. Couldn't have put it any better.
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    (Original post by asem93)
    Agreed. Couldn't have put it any better.
    I think the other man just got a bit confused tbh, but you know, we aren't the examiners, maybe too many people though wrongly about the wording of the question, and they'll even allow them the marks, or remove the question altogether (unlikely, but it has happened).
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    (Original post by DonFahad)
    Soz mate, you've got it wrong. My biology teacher (must be the best in the country, predicted absolutely everything right on the paper, one of the questions word-for-word), said the following;

    One mark for plain diffusion/osmosis through the cell membrane, as water molecules are very small. However, the second mark, will be for mentioning channel proteins, as water molecules, however small, are actually charged, and so a channel protein lets through molecules that are charged. Remember that the Phosphate heads are actually hydrophobic, and that there is a chance that a water molecule could hit that and be repelled. As a result, there are channel proteins that open for water molecules to leave.

    The apoplast and symplast pathways are irrelevant to the cell surface membrane. They are relevant to how water, taken in at the roots, reaches the xylem cells.

    As it happens, I only got the first mark, but think about it, they cannot expect you to explain the apoplastic and symplastic pathways, as well as an explanation of diffusion in two lines and two marks. Even if you somehow managed to fit it in, it is irrelevant because nowhere in the question does it mention that. It mentions cell surface membrane, ie, the plasma membrane, not the symplastic and apoplastic pathways, which go through a number of cells, membranes and plasmodesmata.
    water molecules can pass through via simple diffusion theyre small enough the only time theyd use any form of protein such as aquaporins NOT channel proteins is during pinocytosis.
    They asked for the routes which water takes across the cell surface membrane pretty simple to describe two basic pathways across the cell surface membrane abit more complex to mention aquaporins (not in the specification), the size of the water molecules,the charge of the water molecules being irelevant, and pinocytosis which from past papers is generally one mark in itself.
    like i said in a previous post i hate grey areas and we'll see when the markscheme comes out. JUST because a pathway can go through a number of cell membranes does not mean it ONLY goes through many cell membranes.
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    (Original post by StrawberryKoi)
    :rofl: This made me laugh for some reason. But I see what you mean. I just winged it for that question though.
    the thing is though it said what are microtubules used for in that TYPE of cell and it was a eukaryotic so I reckon any use of microtubules in eukaryots would have been fine
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    (Original post by infernalcradle)
    quick question...

    if it asks for 2 reasons and you put 4-5....

    will the first 2 be marked and the rest ignored, or will all 5 be marked, so reason 1 and 4 are correct you get 2 marks out of 2
    the marks scheme usually (what ive read in pp ms's) says to mark the first 2 and ignore the rest but recent ms's don't mention it...

    nevertheless... some examiners might let you off and mark the others... good luck
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    (Original post by adilh301)
    water molecules can pass through via simple diffusion theyre small enough the only time theyd use any form of protein such as aquaporins NOT channel proteins is during pinocytosis.
    They asked for the routes which water takes across the cell surface membrane pretty simple to describe two basic pathways across the cell surface membrane abit more complex to mention aquaporins (not in the specification), the size of the water molecules,the charge of the water molecules being irelevant, and pinocytosis which from past papers is generally one mark in itself.
    like i said in a previous post i hate grey areas and we'll see when the markscheme comes out. JUST because a pathway can go through a number of cell membranes does not mean it ONLY goes through many cell membranes.
    I mentioned about grey areas in my post above (directly above your post), and I appreciate your point, and I'll want to see the exam markscheme for this. However, I will trust my biology teacher, after guiding me to 400/400 at GCSE, and correctly predicting everything on this paper (ie, she said one of the two mark questions word for word, said very unlikely anything on the heart, lymph, or vessels, said a basic mitosis question, a fill in the blanks regarding either the fetal haemoglobin or the bohr ****, and said plant transport would feature heavily - 14/60, more marks than anything else), I think it's fair for me to go with her definition and thoughts.
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    (Original post by Mobs25)
    the marks scheme usually (what ive read in pp ms's) says to mark the first 2 and ignore the rest but recent ms's don't mention it...

    nevertheless... some examiners might let you off and mark the others... good luck
    my teachers always tell us if it states 2 then you should put 2, because if your first 2 are right, but the 3rd one contradicts it, you won't get any marks
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    (Original post by Mobs25)
    the marks scheme usually (what ive read in pp ms's) says to mark the first 2 and ignore the rest but recent ms's don't mention it...

    nevertheless... some examiners might let you off and mark the others... good luck
    *******s....my teacher said that they should mark all of it....

    but was unsure cos so many on here said otherwise....

    methinks I'll get it remarked if it isn't an A
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    (Original post by CullenLoverX)
    my teachers always tell us if it states 2 then you should put 2, because if your first 2 are right, but the 3rd one contradicts it, you won't get any marks
    but what if nothing contradicts anything else?
 
 
 
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