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    everyone keeps talking about a water potential calc question? like 1600 or something?! why can't i remember this?
    ahhhhh
    it was such a weird exam
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    (Original post by Ralphus J)
    For the cytoskeleton i put vesicles transport substances around cell in and out, something like that. is that right? (i put something else as well it was a 2 marker)

    5 marks for the transpiration question! what was there to say?
    I mean i mentioned as molecules are lost at the top by evaporation to to high potential of water to low potential, this moves the water column up, mentioning cohesion adhesion that crap.. what else?
    Water evaporates from the surface of the leaves through the stomata into the air during gas exchange needed for photosynthesis (1). This creates suction in the xylem (aka tension, transpiration pull) (1). Water is pulled up the xylem. Water molecules are cohesive (1). This means they stick to each other and rise up as a cintinous column. Water also has a property known as adhesion where water molecules are attracted to the walls of the xylem. This aids the transportation of water up the plant (1).

    The fifth one I am guessing comes from using the terms such as Cohesion, Adhesion, Tension/Suction/Transpiration Pull and spelling them correctly.
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    (Original post by lemonpancake)
    everyone keeps talking about a water potential calc question? like 1600 or something?! why can't i remember this?
    ahhhhh
    it was such a weird exam
    I just took the average of the water potential for 57% of the cells and the water potential for 42% and got around -1600kPa
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    (Original post by Dim0nIX)
    I just took the average of the water potential for 57% of the cells and the water potential for 42% and got around -1600kPa
    i literally had 2 seconds for that question..saw the 57% value and wrote that down for the answer for 50% value..do you think ill gett he mark? maybeee there would be a range up to 57% ? i dont know lol :confused:
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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.
    Its asks for the routes across the cell surface membrane not the routes water takes. Its Osmosis (1) through Protein channels (1). As Water is a polar molecule.

    You'd be correct if it asked how water travelled to the Xylem
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    (Original post by dundiddyknoe)
    i literally had 2 seconds for that question..saw the 57% value and wrote that down for the answer for 50% value..do you think ill gett he mark? maybeee there would be a range up to 57% ? i dont know lol :confused:
    oh i remember that question now!
    i couldn't remember it and i panicked that i missed a question. i don't know! i can't really remember what answer i got, or what the question was or anything...so yeah, i'm pretty unhelpful
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    (Original post by dundiddyknoe)
    hey lol i think you read my comment it was exopinocytosis my friend wrote it and i was confused aswell.. apparently it is in the revision guide i checked it and yh it was in a small little box and ocr always try to pick out the things we dont know fully such as diference between plant and animal cell cell division so yh it does make it seem right..also omsosis could be water leaving the cell OR moving into cell..they specifically said moving out of cell so its exopinocytosis (meaning water moving out of cell)
    First of all no such thing as exopinocytosis exsists. There is pinocytosis but it refers to the bulk transport of extracellular fluids into the cell (not out of the cell). Pino means "drink" cyto means "cell" (in Latin). So unless the cell can "drink" so that the water leaves it it makes no sense, since "exo" means "out of". How can a cell drink water causing it to leave it, think logically. The OCR revision guide refers to endocytosis and exocytosis - these have almost nothing to do with water. Water moves in and out of the cell by osmosis. The direction is only determined by the water potential of the cell and its surrounding.
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    (Original post by MadbizL)
    Its asks for the routes across the cell surface membrane not the routes water takes. Its Osmosis (1) through Protein channels (1). As Water is a polar molecule.

    You'd be correct if it asked how water travelled to the Xylem
    Please... water never moves through Channel Proteins. It is polar but it is not an ion! I talked about osmosis and defined osmosis. There is another way for water to move. That is through aqua porines but I never wrote that down in the exam. It just didn't come up in my head for some reason :\
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    (Original post by Dim0nIX)
    Please... water never moves through Channel Proteins. It is polar but it is not an ion! I talked about osmosis and defined osmosis. There is another way for water to move. That is through aqua porines but I never wrote that down in the exam. It just didn't come up in my head for some reason :\
    I simply put From a high water to a low water potential through a selectively permeable membrane, basically explaining osmosis i mean all these people are talking about how water DIFFUSES across the membrane which is wrong isnt it? i dunno
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    Hoping there's a mark for aquaporins... It was even in the texbook
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    (Original post by Dim0nIX)
    Please... water never moves through Channel Proteins. It is polar but it is not an ion! I talked about osmosis and defined osmosis. There is another way for water to move. That is through aqua porines but I never wrote that down in the exam. It just didn't come up in my head for some reason :\
    YES this is what I thought, part a) Osmosis and b) was describing Osmosis.

    When it said cell surface membrane it surely can't mean through the bilayer which is HYDROPHOBIC or through channel proteins since it's not a charged ion.
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    (Original post by HumanNature1992)
    YES this is what I thought, part a) Osmosis and b) was describing Osmosis.

    When it said cell surface membrane it surely can't mean through the bilayer which is HYDROPHOBIC or through channel proteins since it's not a charged ion.
    Yes, the middle of the bilayer is hydrophobic but it doesn't prevent the diffusion of water molecules across the bilayer. The hydrophobic tails do not physically repel water. The bilayer is arranged in this way i) because the hydrophobic hydrocarbon tails attract due to strong Van der Waal forces between them ii) because the charged phosphate group tends to be attracted to polar water molecules. The name hydrophobic is a little bit misleading since it implies they "repel" water which they don't - they just don't attract it and that's it. They are neutral to water (hydroneutralis). Water molecule consists of 3 atoms, 2 of them being effectively the size of one proton. This is perhaps x30 times smaller (estimate) than a single phospholipid molecule. Thus water can freely diffuse through (or move in by osmosis) the bilayer. :cool:
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    (Original post by miss-pink09)
    omg reading through all of what you guys have written in the exam... i have miserably failed
    can someone tell me what that 5mark question answer was? i thought i did good writing about cohesion and adhesion? but was that not correct ?
    I wrote that !
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    (Original post by CourtneeJburton)
    I wrote that !
    yay =D
    the thing is ... this was a re-sit for me..
    and this same question came up in the june exam so i really was quite shocked that this qestion came up again as a 5 marker.
    going through this whole thread ive realised ive dropped about 20 marks altogether :/ not good (N) x
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    Thought this was a pretty tricky exam i revised more than 3 hours the night before making sure i understood the heart 100% and not even a 1 mark question came up.

    what did you lot put for the question where it said what will happen if the capillaries become more permeable...
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    hey, i cant believe it ass well. nothing at all came on the heart!!! its my favourite topic as well. I was hopin like an 8 mark question on cardiac cycle comes lol


    how did u find the other questions...i cant remember them all
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    (Original post by VetApplicant)
    yes, pm with your email address
    can i have a copy of the powerpoint presentation, i know it's a bit late, most appreciated~!!!
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    Thought I'd bring this thread up again, seeing as we get the results tomorrow. eeek. (though I dont actually make that sound in real life)
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    (Original post by Straight up G)
    Thought I'd bring this thread up again, seeing as we get the results tomorrow. eeek. (though I dont actually make that sound in real life)
    The grade boundaries are really low! :O
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    (Original post by MissLightyear)
    The grade boundaries are really low! :O
    Yep, sounds good so far. Approx 11hours 30minutes left for me.
 
 
 
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