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    Give an expiremental procedure that backs the theory of chemiosmosis in oxidative phosporalation and photophosphoralation.
    ( note that a diagram will not be accepted)
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    (Original post by Tinkerbelle ♥)
    go for it
    a) Explain what is meant by negative feedback. (2)


    b) Explain how negative feedback achieves homeostasis.



    c) Explain the differences between negative feedback and postive feedback.

    d) In what way is an action potential considered a positive feedback mechanism.
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    (Original post by MG.GULED)
    Give an expiremental procedure that backs the theory of chemiosmosis in oxidative phosporalation and photophosphoralation.
    ( note that a diagram will not be accepted)
    1) chloroplasts are obtained from a plant
    2)chloroplasts are lysed, thylakoids taken out
    3)thylakoids are put in a ph 4 solution, so that the inter and outer - extracellular spaces have the same concentration of protons (even PH) the tylakoids are then put into a PH 8 solution and PH4 soulution
    5) those in a PH 8 solution make ATP and the those in the PH 4 solution dont
    6) this shows that there must be a proton gradient that allows the protons travel down there gradient Through the ATPase's binding the ADP with an inoraganic phorphate group to make ATP
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    (Original post by Remarqable M)
    a) Explain what is meant by negative feedback. (2)


    b) Explain how negative feedback achieves homeostasis.



    c) Explain the differences between negative feedback and postive feedback.

    d) In what way is an action potential considered a positive feedback mechanism.
    wow , just tested myself mentally and knew the answers to all of these. go me
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    (Original post by MadMaths)
    1) chloroplasts are obtained from a plant
    2)chloroplasts are lysed, thylakoids taken out
    3)thylakoids are put in a ph 4 solution, so that the inter and outer - extracellular spaces have the same concentration of protons (even PH) the tylakoids are then put into a PH 8 solution and PH4 soulution
    5) those in a PH 8 solution make ATP and the those in the PH 4 solution dont
    6) this shows that there must be a proton gradient that allows the protons travel down there gradient Through the ATPase's binding the ADP with an inoraganic phorphate group to make ATP
    spot on mad maths ! i think your ready for this exam
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    (Original post by MG.GULED)
    spot on mad maths ! i think your ready for this exam
    thanks hope so....
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    (Original post by Remarqable M)
    a) Explain what is meant by negative feedback. (2)


    b) Explain how negative feedback achieves homeostasis.



    c) Explain the differences between negative feedback and postive feedback.

    d) In what way is an action potential considered a positive feedback mechanism.
    a) negative feedback is the reversal of a change in the internal enviroment to return to a steady state

    b)not sure on this one but i'm going to go with definition of homeostatsis is to keep the internal enviroment constant despite external conditions. Negative feedback when there is a change to the internal enviroment it's detected and signalled to the other cells. A repsonse to reverse the change , which is what homeostatsis is.

    c) negative feedback is the reversal of a change, positive feedback increases the change

    d) not sure again but maybe because when an action potential is fired, there is no attempt to stop the Na+ channels and K+ channels or to reverse the waves of depolarisation etc it is increased by passing on to the next neurone. - i haven't explained this as well as i'd have liked!
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    [QUOTE=Tinkerbelle ♥]a) negative feedback is the reversal of a change in the internal enviroment to return to a steady state

    b)not sure on this one but i'm going to go with definition of homeostatsis is to keep the internal enviroment constant despite external conditions. Negative feedback when there is a change to the internal enviroment it's detected and signalled to the other cells. A repsonse to reverse the change , which is what homeostatsis is.

    c) negative feedback is the reversal of a change, positive feedback increases the change

    d) not sure again but maybe because when an action potential is fired, there is no attempt to stop the Na+ channels and K+ channels or to reverse the waves of depolarisation etc it is increased by passing on to the next neurone. - i haven't explained this as well as i'd have liked![/QUOTE]


    Almost...I think its the fact that when sodium ions enter, this upsets the balance of the sodium/potassium ions. This leads to a change in membrane potential of the neurone. More sodium ions diffuse as more channels open, allowing a local current to be set up, so action potentials can be carried along. It's positive feedback because the entrance of more sodium ions causes an even bigger change in membrane potential.
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    Not long to go now I'm seriously struggling to grasp Krebs Cycle and Link Reaction for some reason
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    (Original post by Remarqable M)
    ok here is my summarised notes on ultrafiltration:

    Ultrafiltration

    What is it? -Filtration at molecular level where large molecules and cells are left in the blood and smaller molecules pass into the Bowman's Capsule.

    Where does it take place? - In the glomerulus of the kidneys(nephrons).

    What is filtered out? - water, amino acids, glucose, urea and inorganic ions.

    The components needed for unltrafiltration?

    - The endothelium of the capillary
    - A basement membrane (negatively-charged repels negatively-charged proteins from the blood, helping to prevent their passage into Bowman's space.)
    - The epithelial cells of the Bowman's Capsule




    Notes on Selective Reabsorption

    What is it? - The absorption of certain selected molecules back into the blood from the fluid in the nephron tubule.

    Where does it take place? - In the proximal convoluted tubule where about 85% of the re-absorption takes place and the rest of the re-absorption along the nephron.

    What is re-absorbed? - useful substances such as amino acids, glucose and some salts.

    The components required for Re-absorption to work effectively?

    Microvilli - increase the surface area for re-absorption.
    Co-transporter proteins - contained in the cell surface membrane that is in contact with the tubule fluid. Transports glucose or amino acids.

    Na/K pumps - contained in the cell surface membrane opposite to the fluid tubule. Actively transports Na+ and K+ against their concentration gradient.

    Many Mitochondria - provides the energy needed to drive the selective re-absorption process. Many mitochondria= a lot of ATP.

    Hey can you give me any notes on the liver stucture
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    (Original post by shahzebhaq_9)
    Hey can you give me any notes on the liver stucture
    Sure No problemo:borat:
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    1) The main function of the Adrenal Glands is to secrete adrenaline in response to danger excitement or stress.

    2) Adrenalin i a catecholamine synthesised from amino acids and has numerous target tisue which include the sino atrial node and the iris muscle of the eye.

    3) Focusing upon the affect on the liver cells when adrenalin slots into the receptor molecule on the cell surface membrane of a hepatocyte it changes the shape of receptor which causes it to interact with another protein in the membrane called G protein.

    4) this activates the G protein causing it to split and halve of it slots into an inactive enzyme called adenylyl cyclase activating it.

    5) this ezyme converts atp into cyclic amp which acts as the second messenger. Camp then binds to another inacitive ezyme called protein kinase activating it.
    6) yet again protein kinase binds to glycogen phosphoralase kinase which changes it shape and this ezyme then actives the last and main enzyme glycogen phosphoralase.

    7) glycogen phoshporalase catalyses the break down of glycogen into glucose as glycolysis occurs.

    8) glucose then diffuses into the blood and is transported to muscle cells where glucose is metabolised to produce atp. Atp is used as an engergy source to respond to the flee or fight situation.
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    (Original post by CreativeBass)
    Almost...I think its the fact that when sodium ions enter, this upsets the balance of the sodium/potassium ions. This leads to a change in membrane potential of the neurone. More sodium ions diffuse as more channels open, allowing a local current to be set up, so action potentials can be carried along. It's positive feedback because the entrance of more sodium ions causes an even bigger change in membrane potential.
    Thanks Just to clear it up in my head..

    So you could say how the sodium channels open allowing sodium in - this is increased then by (when the threshold is reached) voltage-gated sodium ion channels opening allowing even more to enter.. blaa blaa and same for K+
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    urgh
    I officially hate the kidneys
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    (Original post by chuck111)
    urgh
    I officially hate the kidneys
    Snap, its so much info for such a short topic its deceiving
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    Hiyar
    im new to this
    but do we need to know the differences between
    oxidative phosphorylation
    cyclic phosphorylation
    and non cyclic phosphorylation

    im really strugllin to grasp these
    so if anybody would be willing to explain i would be gratefull
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    (Original post by conorf199)
    Snap, its so much info for such a short topic its deceiving
    i know!!!
    umm im on selective reabsorbtion atm so im almost done
    has taken me some time to get the hang of it because i missed all the lessons when they covered this in class -.-
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    Right today:
    -Finish off respiration
    -Go over kidneys to make sure it all sunk in
    -Control of heart rate

    [If im lucky enough to finish all this then I shall go over Homeostastis and everything just mentioned again]
    - ah im actually calm now but i was panicking in college today (felt so drained) - so stressed out from the last few days couldnt revise properly - was just staring at my respiration mindmap, feel so much better to be home!
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    Ah wednesday is so near - im both dreading and looking forward to it!
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    (Original post by CertifiedAngel)
    Right today:
    -Finish off respiration
    -Go over kidneys to make sure it all sunk in
    -Control of heart rate

    [If im lucky enough to finish all this then I shall go over Homeostastis and everything just mentioned again]
    - ah im actually calm now but i was panicking in college (felt so drained) - so stressed out from the last few days couldnt revise properly - was just staring at my respiration mindmap, feel so much better to be home!
    not alot really if you put ur mind to it
    i have the whole of photosynthesis and respiration to cover tonight,however i like those topics
 
 
 
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