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    this is very bad..im still on module one! arghhhhhh cant wait till its over.
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    Remind me what division of labour is again....? ?
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    Can anyone explain how you would work out the actual size of a drawing of a cell/organism
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    Wooooooooooo

    get this badboy done!
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    Can someone expalin these please...to help me understand them better!!

    1: Explain the role of membrane bound receptors as sites where hormones and drugs can bind??

    2: what are epithelial cells???...specialised??

    3. how are cells organised into tissues using squamous and ciliated epithelia as examples??

    4. explain the significance of the different affinities of fetal and adult haemoglobin for oxygen?

    these are just the topics im a bit stuck on!! :confused:
    Thanx x
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    (Original post by hellosarah)
    Remind me what division of labour is again....? ?
    Division of labour is when organelles work out different functions for the cell. E.g. the whole protein synthesis when the nuclues produces the ribosomes, the amino acids are assembled at the ribosomes to make proteins, the rough endoplasmic reticulum transports the proteins to the golgi apparatus where they are then modified and packaged.

    Well I think it is. I only have my little thin revision guide with me, I'll check when I get home.
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    (Original post by Princess Kawaii)
    Can someone expalin these please...to help me understand them better!!

    1: Explain the role of membrane bound receptors as sites where hormones and drugs can bind??

    2: what are epithelial cells???...specialised??

    3. how are cells organised into tissues using squamous and ciliated epithelia as examples??

    4. explain the significance of the different affinities of fetal and adult haemoglobin for oxygen?

    these are just the topics im a bit stuck on!! :confused:
    Thanx x
    1- Membrane bound receptors have a specific recognition site which has a complementary shape to this specific hormone or drug. Any cell with a receptor is called a target tissue.
    So the hormone/drug binds to the receptor on a target cell surface membrane, causing the target cell to respond in a particular way.
    Some medicinal drugs block receptors.

    2 + 3- Epithelial cells:
    Squamous epithelial tissue:
    - Thin, smooth, flat surface.
    - Provides a short diffusion pathway. E.g: in alveoli; for the exchange of oxygen and carbon dioxide.
    Cilliated epithelial tissue:
    - Made up of column-shaped cells; cillia.
    - Cillia wave in a synchronised rhythm to move mucus.
    E.g: in the breathing tract & moving egg cells along the oviduct.

    4 - A developing fetus obtains oxygen from its mother's blood and its own lungs.
    Oxygen arrives at the placenta in combination with haemoglobin.
    The partial pressure of oxygen in the blood vessels in the placenta is relatively low, as the fetus is respiring. Therefore, the mother's haemoglobin releases some oxygen, diffusing from the blood into the fetus's blood across the placenta.
    Partial pressure of oxygen in the fetus's blood is only a little lower than that in its mother's blood, meaning diffusion would occur at a very slow rate.
    BUTT this doesn't happen as fetal haemogblobin combines more readily with oxygen than adult haemoglobin.
    Fetal haemoglobin is said to have a HIGHER AFFINITY for oxygen than adult haemoglobin. So at any partial pressure of oxygen, fetal haemoglobin will take oxygen from adult haemoglobin.

    Does any of that even make sense? :confused:
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    (Original post by pastpaper-guy)
    i bet theres going to be a 5 marker on setting up a potometer.
    I hope not! Hate potometer with a passion


    EDIT: what the neg rep for?
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    (Original post by 786girl)
    does anyone else think that, after doing all the past papers for this spec that, 2010 may was the hardest? no wonder im having to resit it
    yes it definately was the hardest one i sat. the yeast buding surprised me and using the data about the blue yeast cells was abit tricky.


    i think we should start a list of definitions that could possibly come up.
    il start the list:
    • Stem cells
      SEM
      TEM
      Resolution
      contrast
      magnification
      mitosis
      homologonoues or however u spell that


    anymore suggestions?
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    (Original post by pastpaper-guy)

    anymore suggestions?
    cell signalling
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    (Original post by xMaGic)
    Hardest topics; Haemoglobin (fetal, affinity, etc), CO2 Distribution (5% in blood plasma, 10%..etc), LYMPHATIC system, Translocation.
    What do you guys think?
    I think all of that apart from the haemoglobin is going to come up lolz
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    (Original post by livingforthefuture)
    Can anyone explain how you would work out the actual size of a drawing of a cell/organism
    anyone?
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    Actual size = Image size/Magnification ?
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    (Original post by livingforthefuture)
    anyone?
    Actual size = image size / magnification

    so you measure the size of the organelle using a ruler and then divide it by the magnification which they give you
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    (Original post by livingforthefuture)
    anyone?
    - measure size of image given (mm)
    - multiply by 1000 (convert to micrometers)
    - divide by the magnification (given or work it out- see below)
    = actual size (in micrometers)

    If you don't know the magnification and can't work it out from
    magnification = size of image over actual size,

    then work out magnification from the scale line:

    magnification = length of scale line given divided by length of scale line measured (mm)

    hope that helped
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    (Original post by hellosarah)
    Actual size = Image size/Magnification ?
    looks like we posted the answer at the same time!
    How is your revision going? Ready for tomorrow?
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    (Original post by anonymous_angel_16)
    looks like we posted the answer at the same time!
    How is your revision going? Ready for tomorrow?
    hahhaha, i am never ready!! I'm retaking it, if i get an E again, i may just have a mental crisis. Are you ready?
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    (Original post by pastpaper-guy)

    anymore suggestions?
    possible definitions of-
    diffusion, osmosis, active transport maybe?
    endocytosis and exocytosis
    tissues, organs, organ systems
    spirometer lung volumes (tidal volume, vital capacity etc)
    transpiration, xerophytes, translocation
    open/closed circulation
    single/double circulation
    valve functions
    tissue fluid

    any more do you think?
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    I hope this comes up:
    "Outline the cell cycle" (9marks) (1 for QWC)

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    possible how science works questions?
 
 
 
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