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    (Original post by KDudley)
    can anyone teach me about xylem and phloem? and transpiration etc.
    Transport through xylem/phloem or adaptations/features
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    (Original post by xMaGic)
    Cardiac cycle;

    1. Relaxation of Ventricles and atria.
    2. Blood enters atria from veins returning to heart
    3. Atria fill with blood
    4. Atria contract (atrial systole)
    5. Blood passes into ventricles
    6. Through atrioventricilar valves
    7. Atrioventricular valves shut to prevent backflow back into atria
    8. Ventricles contract (ventricular systole)
    9. Blood passes out into arteries leaving the heart through open semilunar valves
    10. Semilunar valves shut to prevent backflow
    Makes more sense now, thanks
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    (Original post by emmaD96)
    Makes more sense now, thanks
    No problem
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    (Original post by xMaGic)
    Transport through xylem/phloem or adaptations/features
    Transport through xylem/phloem pleasee
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    Translocation is the movement of assimilates from one part of a plant to another via the phloem;

    1. Hydrogen ions are pumped out of the companion cell (requires energy - ATP)

    2. Hydrogen ions diffuse back into companion cell through a cotransporter protein.

    3. At the same time as the cotransportr transports H+ it
    also transports sucrose.

    4. Sucrose diffuses into seive tube elements through plasmodesmata

    5. Diffusion of sucrose into seive tube elements reduces water potential

    6. Water moves in by Osmosis from surrounding tissue

    7. This increases the pressure (hydrostatic)

    8. In the cells surrounding the phloem, sucrose is used up which decreases the sucrose concentration

    9. Sucrose from phloem diffuses in to surrounding tissue

    10. Water potential gradient is now higher sieve tube element than surroundng tissue so water moves by osmosis out of the sieve tube element

    12. This decreases the pressure

    13. Water in phloem moves down PRESSURE gradient and carries with it the sucrose.
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    Oh gosh..why do i feel the need to pull out a tex t book now! :L
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    (Original post by KDudley)
    Transport through xylem/phloem pleasee
    Water transport from root to leaves;

    Water enters the roots by osmosis. At the same time, minerals are actively pumped from the root cortex into the xylem. This causes the water to move from the root hair cells along the symplast pathway to follow the xylem. Thw symplast pathway is where water enters the cytoplasm from cell to cell. Water can also travel through the apoplast pathway, where water travels between the cell walls without passing through the plasma membranes. The Casparian strip blocks the apoplast pathway between the cortex and the xylem meaning that, to reach the xylem the water MUST join the symplast pathway.
    When thw water reaches the top of the xylem, it enters the leaves and leaves through the stomata.
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    thankyouu
    thats just what i needed, written in a simple way for me to understand!
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    (Original post by KDudley)
    thankyouu
    thats just what i needed, written in a simple way for me to understand!
    Np.
    Let me know if anything else ur stuck on
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    Biology! Although I love it to bits, it is rather stressful. There are too many words to learn .
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    (Original post by beanstalkgirl_24)
    Biology! Although I love it to bits, it is rather stressful. There are too many words to learn .
    Yep, too much content.
    Keep copying notes and stuff until you get it in your head
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    (Original post by xMaGic)
    Yep, too much content.
    Keep copying notes and stuff until you get it in your head
    Thanks thats good advice.

    Also have any of you used Quizlet the online flashcards website before??? Its rather splendid (I do love that word!!) and in my revision last week I managed to find loads of flashcards by someone called '03harmal' who obviously did the exam last January. They are for all of the topics in the January exam and worth a look as a different style of revision....(you can play games with them )

    Link: http://quizlet.com/user/03harmal/

    PS If this has been helpful can you rep me...I'm determined to get to level 2!!!

    TY
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    (Original post by VetApplicant)
    I have a 50 slide revision powerpoint for OCR AS Biology last year
    If anyone wants it, just tell me how to send it and I will
    Hiya could you possibly send it to me......It would be great. Thanks Danielle
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    How much are you guys revising daily?
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    (Original post by daniellestaunton)
    Hi would it be possibly if you could send them to me as well. Thanks
    sure, just private message me your email thingy
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    (Original post by beanstalkgirl_24)
    Thanks thats good advice.

    Also have any of you used Quizlet the online flashcards website before??? Its rather splendid (I do love that word!!) and in my revision last week I managed to find loads of flashcards by someone called '03harmal' who obviously did the exam last January. They are for all of the topics in the January exam and worth a look as a different style of revision....(you can play games with them )

    Link: http://quizlet.com/user/03harmal/

    PS If this has been helpful can you rep me...I'm determined to get to level 2!!!

    TY
    Thank you so much for this!!!

    Its a really helpful website and its the thing that got me revising!

    Thanks again for the link
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    So, based on what's come up on the last few papers of this spec, what topics do you reckon will come up on the January 2011 paper!? :confused:
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    sorry, just looked through the powerpoint I sent people and it looks a bit rubbish!
    I remember it being better than that!
    Sorrryy!
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    Does anyone have an easy way of remembering things about cells e.g. the organelles as I just can't remember them at all? It does not go into my head. Actually to be honest none of this stuff is going in my head, I sit there, basically write it all out and it still doesn't go in.
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    Which book do you revise from people?. I have the fear that the thin revision book doesn't go into enough detail.
 
 
 
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