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    Was there a question on ECGs I can't remember?

    :L
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    was it 4500x ?
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    The 6b question, was about how water passes through the membrane. So diffusion and specially adapted channel protiens - aquasomething or another .

    Also, the cutting the stem off the stem of the flower. I didn't know what it was, my teacher said (I asked afterwards) "There may be an air bubble in the xylem when you first cut off the flower from the plant, by cutting it again just before you put it in water, there is still a continuous column of water molecules" Something along that.

    Personally, I didn't think this paper was harder than any other papers, but some of the questions were so vague. Like really vauge, and there was so many suggest questions too.

    Finally. How did everyone answer the water potential of the onion cell?
    Three ways people have done it
    -Estimate around -1700
    -Half the 100% value to get -1750
    -Find the difference between percents, and water potentials to be 19.444444, then multiple that by 7. Add number to -1850? <- I did it this way, but I think it may be wrong. I ended up getting -1664
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    (Original post by emzywemzy)
    what did people put for the working out magnification question? i always mess them up!
    Image size was 9cm, equal to 90,000um (micrometers). 90,000um divided by 20um was 4500x.
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    (Original post by ALZ-93)
    Image size was 9cm, equal to 90,000um (micrometers). 90,000um divided by 20um was 4500x.
    oh nooo! hahaha definitely didn't get that mark then whoops!
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    (Original post by Iepnauy)

    Personally, I didn't think this paper was harder than any other papers, but some of the questions were so vague. Like really vauge, and there was so many suggest questions too.

    Finally. How did everyone answer the water potential of the onion cell?
    Three ways people have done it
    -Estimate around -1700
    -Half the 100% value to get -1750
    -Find the difference between percents, and water potentials to be 19.444444, then multiple that by 7. Add number to -1850? <- I did it this way, but I think it may be wrong. I ended up getting -1664
    I think I put -1650 as it was just a guess. I thought it was closer to the -1800 one than the one below it so thats what I put down. It was a bit of a random question so I hope the mark scheme has a big allowance on it.
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    (Original post by Ambrosse)
    No, water travels across the cell membrane by diffusion as molecules small enough to pass right through charged area and also channel proteins and aquaporines to allow bulk movement of water, pinocytosis.

    Apoplast and symplast just refers to water travelling through the root doesnt it.
    mmm i dno i thought route would just be referring to the routes water molecules take going across cell surface membranes your answer sounds correct though nvm the aquaporins thats but channel proteins for pinocytosis and diffusion for general osmosis. but i think they were looking more for the symplast and vacuolar pathway.

    you'll see why im saying this if you look at page 73 of the OCR textbook;
    if i remember correctly the question asked which routes water molecules took across the plasma membrane? or something along those lines.

    How does water move between cells?
    When plant cells are touching each other,water molecules pass from one cell to another. The water molecules will move from the cellwith the higher water potential to the cell with lower water potential.
    What route can water take between cells?
    there are three possible pathways that water molecules can take between cells:
    the Apoplast pathway
    the Symplast pathway
    the vacuolar pathway
    thats from the book and seems to be what the question was asking aswell, but hopefully the mark scheme is leniant since questions on this paper were so vague.
    and yeah you can say apoplast if u mentioned symplast and vacuolar apoplast wont lose you marks but wont gain you any marks either i dont think.
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    (Original post by Iepnauy)
    The 6b question, was about how water passes through the membrane. So diffusion and specially adapted channel protiens - aquasomething or another .

    Also, the cutting the stem off the stem of the flower. I didn't know what it was, my teacher said (I asked afterwards) "There may be an air bubble in the xylem when you first cut off the flower from the plant, by cutting it again just before you put it in water, there is still a continuous column of water molecules" Something along that.

    Personally, I didn't think this paper was harder than any other papers, but some of the questions were so vague. Like really vauge, and there was so many suggest questions too.

    Finally. How did everyone answer the water potential of the onion cell?
    Three ways people have done it
    -Estimate around -1700
    -Half the 100% value to get -1750
    -Find the difference between percents, and water potentials to be 19.444444, then multiple that by 7. Add number to -1850? <- I did it this way, but I think it may be wrong. I ended up getting -1664
    The tutor was just about to call time up so I just had quick look and put -1600, well it did say estimate. lol
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    (Original post by Ambrosse)
    The tutor was just about to call time up so I just had quick look and put -1600, well it did say estimate. lol
    what did people say for the how would you use a graph question?
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    (Original post by Ambrosse)
    Do you think that for plant cell wall one you needed to put about the cell membrane pushing against the wall. I just put cell wall prevents bursting but now looking back im thinking mayb that bit was required also.
    that was the 2 mark one right? i just wrote:
    The cell wall has pressure potential preventing the cell from bursting, when the cell becomes turgid the cell wall stops allowing water to pass through :/ easy paper but written disabledly hopefully i scrape an A
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    (Original post by blahblah772)
    what did people say for the how would you use a graph question?
    I just guessed quickly again and just put plot water potential by amount % plasmolysed. Really I just answered those so quick I barely even thought about them. Did that sound right though ?
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    (Original post by blahblah772)
    what did people say for the how would you use a graph question?
    scatter graph/line graph with i fink either of the first 2 for the x-axis and %age for the y-axis.
    if you did scatter u mention a line of best fit to measure the estimates tbh i did scatter graph so dno what would score marks for line im not even sure my answer for scatter graph would score me any marks hopefully someone got the same as me.
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    (Original post by adilh301)
    that was the 2 mark one right? i just wrote:
    The cell wall has pressure potential preventing the cell from bursting, when the cell becomes turgid the cell wall stops allowing water to pass through :/ easy paper but written disabledly hopefully i scrape an A
    Yes it was for two marks. Possibly one mark for stating cell is turgid and next for saying cell wall prevents bursting. But also plasma membrane swells and I dont know if that could be one of the marks.
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    (Original post by adilh301)
    scatter graph/line graph with i fink either of the first 2 for the x-axis and %age for the y-axis.
    if you did scatter u mention a line of best fit to measure the estimates tbh i did scatter graph so dno what would score marks for line im not even sure my answer for scatter graph would score me any marks hopefully someone got the same as me.
    What did the question ask for again. I think plotting % of cells haemolysed by concentration of water would give good indication of how water potential effects onion cells. But I cant remember what question was.
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    (Original post by adilh301)
    scatter graph/line graph with i fink either of the first 2 for the x-axis and %age for the y-axis.
    if you did scatter u mention a line of best fit to measure the estimates tbh i did scatter graph so dno what would score marks for line im not even sure my answer for scatter graph would score me any marks hopefully someone got the same as me.
    I said a scatter graph with a line of best fit and then reading off where the water potential meets the % plasmolysed on the line of best fit... I didn't explain it very well but does that sound right?
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    yes I think that must be correct.
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    (Original post by adilh301)
    Yeah symplast and vacuolar pathway across the membrane, going through channel proteins would be wrong even if the question asked how water moved through the phospholipid bilayer i think bc water molecules are an exception to that rule as theyre small enough to travel through the hydrophobic tails. but yeah symplast and vacuolar pathway
    yh i put symplast and vacullar pathways- not apoplast because substances are carried between cells here only forced into symplast by casparian strip at endodermis i think
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    (Original post by adilh301)
    that was the 2 mark one right? i just wrote:
    The cell wall has pressure potential preventing the cell from bursting, when the cell becomes turgid the cell wall stops allowing water to pass through :/ easy paper but written disabledly hopefully i scrape an A
    You should get two marks.
    I think the two marks, you'd get by mentioning cell wall and pressure.
    When a cell becomes turgid, the cell pushes out with equal pressure to the water coming in (something along those lines). So water still passes through it, but water is being pushed out at the same time (I think).
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    (Original post by Ambrosse)
    What did the question ask for again. I think plotting % of cells haemolysed by concentration of water would give good indication of how water potential effects onion cells. But I cant remember what question was.
    yeah thats thats what i did i think it can be either of the two since your looking for a percentage of the cells plasmolysed i did the x coordinate dependant on the question though i think i got the marks for that question but didnt ask friends what they got for it lol so idk :/
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    (Original post by Normandy114)
    I put the part where the airway split (part a I believe) as Bronchus, and part b was alveoli of course.
    I think I've done relatively well on this test, but it didn't have any questions on the heart or bohr shift (if you don't include the fill in the gaps question) which is what I revised...
    ahh i see ive forgotten the picture if the arrow it was pointing to had a cartrlidge
 
 
 
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