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    (Original post by dansheriff)
    Evidence for the use of the phloem

    - If a plant is supplied with radioactively labelled carbon dioxide, the carbon soon appears in the phloem

    - ringing a tree to remove the phloem causes sugars to collect above the ring

    _ An aphid feeding on the plant stem leaves mouthparts showing it is taking food from the phloem.
    no it takes is from the leaves showing that there is a higher pressure in the leaves. or something.
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    So bets are on translocation, mitosis and the heart? great
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    My textbook says that an aphid feeds from the phloem, which is located on the plant stem...how sure are you about this leaf thing?
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    (Original post by dansheriff)
    My textbook says that an aphid feeds from the phloem, which is located on the plant stem...how sure are you about this leaf thing?
    they take it from the stem.
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    Ok thanks for clearing that up gradu
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    (Original post by dansheriff)
    My textbook says that an aphid feeds from the phloem, which is located on the plant stem...how sure are you about this leaf thing?
    can you link me to your older post concerning everything to do with sources, sinks and translocation? it was quite long, it had correct heading in bold and everything. Ive looked for it but I cant find it, was it in this thread?
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    (Original post by dansheriff)
    My textbook says that an aphid feeds from the phloem, which is located on the plant stem...how sure are you about this leaf thing?
    cgp textbook?
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    (Original post by Rosi M)
    Carriage of CO2

    CO2 transported in blood in 3 main ways:
    1) 85% in the form of Hydrogen carbonate ions
    2) 5% dissolves directly in plasma
    3) 10% combines with haemoglobin to form carbaminohaemoglobin

    When there is a HIGH PARTIAL PRESSURE OF C02 so basically lots of C02 for eg. during exercise (cells respiring more), C02 will combine with water to form carbonic acid. Enzyme called CARBONIC ANHYDRASE catalyses this.

    Carbonic acid dissociates forming HCO3- and H+.
    HCO3- diffuses out red blood cells. Chloride ions enter to maintain charge. This is called CHLORIDE SHIFT. To stop the red blood cell becoming too acidic, haemoglobin accepts the H+ forming HAEMOGLOBINIC ACID.

    Now this does 2 things:
    1) Acts as a buffer so maintains PH cos remember H+ makes environment acidic.
    2) H+ COMPETE with OXYGEN for a place in the haemolgobin molecule. So Haemoglobinic acid causes OXYHAEMOGLOBIN to dissociate more releasing more oxygen.

    This is really useful when your doing lots of exercise so in muscle cells. More exercise so more CO2 (increased respiration) so more H2CO3 (carbonic acid) so more H+ so more HAEMGLOBINIC ACID so more oxygen to muscle cells.

    Thats CO2 carriage
    That was seriously good. I really, really, really appreciate that. How you turned 2 pages of notes into 1 sentence.

    I dont know about your plans for the future, but looking from the rest of your post, you'd be great as a private tutor (as a student job or something). Rep to be given too...
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    Can anyone list the adaptations of neutrophils, epithelial cells, palisade cells, and guard cells

    Thanks
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    (Original post by stressedoutbadly247)
    Hey, any chance i could have this 50m slide powerpoint?
    would be much appreciated
    hey i would love u 2 send me dat , ???
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    http://www.thestudentroom.co.uk/show...7#post29211537

    for the translocation notes
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    One last question from me!

    Can someone please list xylem and phloems structure, and how it is related to it's function?
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    anyone think there'll be a question on the cytoskeleton?

    can anyone explain what it is please?
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    (Original post by dansheriff)
    http://www.thestudentroom.co.uk/show...7#post29211537

    for the translocation notes
    cheers, much, much appreciated.
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    (Original post by DonFahad)
    cheers, much, much appreciated.
    No problem
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    (Original post by CullenLoverX)
    anyone think there'll be a question on the cytoskeleton?

    can anyone explain what it is please?
    The cytoskeleton refers to the network fibres found within cells that gives structure and shape to cells holding them in place.

    It allows organelles to be moved inside the cell, i.e. moves chromosomes during nuclear division
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    (Original post by dansheriff)
    Can anyone list the adaptations of neutrophils, epithelial cells, palisade cells, and guard cells

    Thanks
    Anyone?
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    (Original post by Wilko94)
    One last question from me!

    Can someone please list xylem and phloems structure, and how it is related to it's function?
    Xylem - transport of water and dissolved minerals UP the plant
    - no end walls
    - no cell contents
    - lignified walls - waterproofs cell and provides support (in a spiral shape to allow flexibility of xylem)
    - also has some parenchyma cells.
    - bordered pits to allow water to enter adjacent vessels to reach different parts of the plant, or enter living parts of the plant.

    Phloem - transport of sucrose up and down the plant.
    - sieve tube elements - have sieve plates
    - Companion cells - linked to sieve tube elements by thin layer of dense cytoplasm to allow transfer of sucrose
    companion cells actively transport H+ ions out of cell against concentration gradient, which then diffuse back into the cell through contransporter proteins which allows sucrose to enter the cell, which can then pass into the sieve tube elements by Diffusion.
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    (Original post by dansheriff)
    The cytoskeleton refers to the network fibres found within cells that gives structure and shape to cells holding them in place.

    It allows organelles to be moved inside the cell, i.e. moves chromosomes during nuclear division
    thanks. so if there was a 2 mark question i would just need to state
    a) it gives the cell structure
    b) moves organelles?
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    (Original post by wilsea05)
    Xylem - transport of water and dissolved minerals UP the plant
    - no end walls
    - no cell contents
    - lignified walls - waterproofs cell and provides support (in a spiral shape to allow flexibility of xylem)
    - also has some parenchyma cells.
    - bordered pits to allow water to enter adjacent vessels to reach different parts of the plant, or enter living parts of the plant.

    Phloem - transport of sucrose up and down the plant.
    - sieve tube elements - have sieve plates
    - Companion cells - linked to sieve tube elements by thin layer of dense cytoplasm to allow transfer of sucrose
    companion cells actively transport H+ ions out of cell against concentration gradient, which then diffuse back into the cell through contransporter proteins which allows sucrose to enter the cell, which can then pass into the sieve tube elements by Diffusion.
    Wilsea, do you know the adaptations of guard cells?
 
 
 
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