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    Soooo, do we have anything related to Unit 5 and the article here yet? Because i feel I'm studying the article in the wrong way.
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    (Original post by J_Jaweria)
    Soooo, do we have anything related to Unit 5 and the article here yet? Because i feel I'm studying the article in the wrong way.
    Annaaix_ sent us biosolutions thing and that's all you need for article thing I believe!
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    (Original post by Kamran Fazal)
    Guys I don't take biology but some of my classmates take biology and their teacher is gonna make them write expected questions. If you guys want them I can give it to you guys.
    May I get it too?
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    Yes please.
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    I know this sounds so selfish and I'm sorry! But I get soso many requests (100+) for the biosolutions thing it's a little difficult to keep up and I spend so long every day sending them to people I'm not gonna be giving them out anymore, I really hope someone I sent them to is willing to take over, best of luck with revision & exams x
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    Could someone please help me with this??Name:  Capture.PNG
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    Can someone help me by explaining difference between diffusion gradient and electrochemical gradient? It is in june2010 mark scheme question 2C
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    (Original post by Aimen.)
    Could someone please help me with this??Name:  Capture.PNG
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    You'll say that rhodopsin is broken down to opsin and retinal due to changing of cis-retinal to trans-retinal causing strain on bonds between opsin and retinal so they separate.Opsin binds on cell surface membrane causing Na+ channels to close in outer segment but sodium ion pump in inner segment is working pumpingNa+ out so inside is more negative in relation to outside causing memrane of rod cell to be hyperpolarised

    Correct me if I am wrong hope It would help
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    (Original post by Annaaix_)
    I know this sounds so selfish and I'm sorry! But I get soso many requests (100+) for the biosolutions thing it's a little difficult to keep up and I spend so long every day sending them to people I'm not gonna be giving them out anymore, I really hope someone I sent them to is willing to take over, best of luck with revision & exams x
    Guys I'll be sending the biosolutions thing Annaaix_ sent to anyone who asks (whoever you are).
    Pm me your email id.
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    (Original post by Aimen.)
    Guys I'll be sending the biosolutions thing Annaaix_ sent to anyone who asks (whoever you are).
    Pm me your email id.
    This is why I love you
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    (Original post by Annaaix_)
    This is why I love you
    Ayee xo
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    (Original post by Abdelrahman 1998)
    Can someone help me by explaining difference between diffusion gradient and electrochemical gradient? It is in june2010 mark scheme question 2C
    The diffusion gradient is because of the respective gradients of of Na ions and K ions maintained by the sodium potassium pump. More Na ions outside, more K ions inside the axon (therefore less k ions outside). The electrochemical gradient is set up when K ions leave the axon down the k ion diffusion gradient (this makes the the outside more positive and the inside more negative) therefore there is an electrochemical gradient now that will pull positive K ions back into the axon (since like charges attract) the resting potential is achieved by a balance of this diffusion gradient and electrochemical gradient when there is no more net movement of K ions.
    That's all I can make of it right now, I don't know if that helps,
    I was hoping I could get the solutions too if it isn't too much trouble
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    Can You pls pls send me the biosulutions thingy. It would be of much help.
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    (Original post by inaam95)
    Can You pls pls send me the biosulutions thingy. It would be of much help.
    Sent! x)
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    Could someone please help me with this?
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    When a person is infected with HIV the CD4 T lymphocytes decrease in first 6 weeks as when virus particles leave, they kill the cells and T Killer cells also destroy T helper cells, but then why do they increase after 6 weeks
    (Although it wasn't asked in the paper but I still wondered)
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    (Original post by Aimen.)
    Could someone please help me with this?
    Name:  Capture.PNG
Views: 88
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    When a person is infected with HIV the CD4 T lymphocytes decrease in first 6 weeks as when virus particles leave, they kill the cells and T Killer cells also destroy T helper cells, but then why do they increase after 6 weeks
    (Although it wasn't asked in the paper but I still wondered)
    Which year is it?
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    Please give me a model answer for this question Name:  image.jpg
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    (Original post by Quirky01)
    Which year is it?
    It's unit four, Jan 2010.
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    Please someone answer my previous question .
    And I need someone to kindly tell me whether to write oxidised NAD or NAD only when reduced NAD loses hydrogen atoms?
    Thanks in advance.
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    (Original post by Abdelrahman 1998)
    Please someone answer my previous question .
    And I need someone to kindly tell me whether to write oxidised NAD or NAD only when reduced NAD loses hydrogen atoms?
    Thanks in advance.
    Just write NAD.

    For your first question you don't need to know why they increase. It may be due to treatment, or anything, but the question only asks you about the first 6 weeks so ignore it. It could just be an error on edexcel's part.
 
 
 
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