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AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011 watch

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    (Original post by SarahTM)
    Glycogenesis is where glucose is converted into glycogen...

    Gluconeogenesis is where glycogen is converted to glucose with the aid of the enzyme glucagon
    Right, apart from glucagon isn't an enzyme. It stimulates enzyme action increasing Gluconeogenesis indirectly.
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    (Original post by Jin3011)
    lol sorry, I didn't quite get that.
    you know after splicing, you are left with the exons and they go into translation where they are complimentary to the bases on the tRNA. If they asks for the bases, would you give both the tRNA and the exons? Hope that is better
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    (Original post by SirMuffin)
    Folks... Can anyone kindly give me the AQA definitions (if such a thing existed) for negative feedback and positive feedback?
    I know neg feedback is: (2marks)
    Departure from normal level;
    causes change to restore normal level
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    (Original post by arvin_infinity)
    FSH is extracted from the urine of menopausal women. The menopause is when a woman’s menstrual cycle stops during middle age. By this time, menopausal women have few follicles left in their ovaries. These women have large amounts of FSH in their urine.
    Explain why these women have large amounts of FSH in their urine.
    22:24
    (2 marks)

    Thought its to do with progesterone ..

    Someone help me out with this question

    +rep

    basically think its to do with..
    few folicles mean less oestrogen produced.
    that means less oestogren hence less it will inhibit fsh....therefore more fSH produced.
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    (Original post by IFondledAGibbon)
    Right, apart from glucagon isn't an enzyme. It stimulates enzyme action increasing Gluconeogenesis indirectly.
    Oops
    Sorry :']
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    (Original post by NRican)
    Can anyone quickly summarise osmosis in Cholera and Digestion (small intestine - dehydration etc)

    Would be greatly appreciated. Unit 1 stuff not coming back to me
    Cholera bacterium releases a toxin in the large intestine. This binds and opens chloride channels on the epithilium surface.
    Cl ions flood out into the lumen, lowering the water potential. This draws water out of the epithilium cells by osmosis down a water potential gradient.
    This may lead to chronic diarrohoea(cant spell) or dehydration.
    To rehydrate the cells we use an oral rehydration solution which contains glucose and na+. These species are taken up by co transport in the small intestine region, lowering water potential of the epithilial cells, allowing reabsorbtion of water.
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    (Original post by SarahTM)
    All nighter anyone?
    :cool:
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    (Original post by bobsaeed)
    hey this is just some ideas
    nitrogen:
    -important in DNA and Amino acids
    -fertilisers

    transfer of energy:
    -trophic levels and inefficiency though the levels (unit4)
    -action potentials
    -ATP is the intermediate energy transfer molecule
    - energy in chemiosmotic gradients in ETC, H+ runs though ATP synthase causes ATP to be made(Also the electron transport chain in general)

    water:
    in photosynthesis, water is broken in photolysis into H+ e- and O2, these H+ combines with NADP, e- is used in electron transport chain
    -water is wher life started
    -hydrolysis reactions breaking ATP and proteins apart
    -cystic fibrosis in lungs
    -polar so things can dissolve, allowing ions to be formed (plant roots)
    -hydrogen bonding, transpiration

    surface area:
    -Axon diameter effects speed of impulse
    -SA in leaf for max light absorbs
    -more proteins in higher surface area, e.g. chlorophyll on thylakoid membranes
    -SA:V ratio in temp control, heat loss and respiration
    -vasoconstriction/dilation

    Hydrogen:
    -Electron transport chain
    -photosynthesis
    -co enzymes in respiration, also glycolosis and the actions of NAD
    -hydrocarbons, (most organic molecules)
    -acidic conditions (caused by H+ ions), Hb in blood
    -hydrogen bonds also happen when proteins gain secondary structure

    sorry its not much but i hope this is any help and its not to late ahah x
    Thank you!
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    can someone summarise rod cones cells and stuff about the eye please .. i dont know what type of detail to learn it in
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    (Original post by cws121)
    gluconeogenesis is the formation of glucose from fatty acids and glycerol- i.e. forming new glucose (glucagon activates this by binding to liver)

    glycogenesis- the formation of glycogen from glucose (insulin activates this)

    glycogenolysis- the formation of glucose from glycogen (strictly speaking we dont have to know the name for that- we just have to know that glucagon activates an enzyme that breakdown glycogen to glucose)

    hope that helps
    thanks.
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    (Original post by Master.K)
    Could somebody explain restriction mapping to me please.
    Restriction mapping is used to find the correct sequence of DNA fragments that have been cut up. Use different restriction enzymes to cut a labelled strand at different places, then use electrophoresis to separate the cut strands. Then you have to use the total digest, partial digest and separate restriction enzyme bands formed on the electrophoresis gel to piece together how the original strand should have been.

    It's pretty hard to explain but it's really just a puzzle, the Partial digest shows different cuts when not all the cuts have finished. For example if a line was like:
    ______ and got fully cut (Total digest) to __|_|___|_ you'd see 4 bands on the total digest. However the partial digest may show __|______, and __|_|_____, and ___|____ so will have more bands showing as not all the enzymes have cut yet.

    Then you have to use the radioactive markers to piece it together, usually told the radioactive marker is at the beginning.
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    (Original post by won-derer)
    you know after splicing, you are left with the exons and they go into translation where they are complimentary to the bases on the tRNA. If they asks for the bases, would you give both the tRNA and the exons? Hope that is better
    Sorry, I'm keep getting a mind block I've got really bad cognitive processing it seems.
    But they would really make it obvious on the question as to what they're looking for.
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    If the women have few follicles left in their ovaries, that means the follicles are unlikely to be stimulated each month. When a follicle is stimulated by FSH the follicle starts to secrete oestrogen, which in turn feedback inhibits FSH production by the pituitary. So, if not follicle is stimulated in a menopausal woman, there is not oestrogen to feedback inhibit FSH production, therefore the woman's FSH levels will be high.
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    how is insulin produced by genetically modified organisms?
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    ANYBODY have any idea of what essay topic may come up?

    Thanks! And good luck everyone!
    Am terrified about this exam :I
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    Right I'm off to get some sleep before tomorrow. Best of luck everyone!
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    What / How many topics involve osmosis for the essay?


    (Original post by Jin3011)
    Cholera bacterium releases a toxin in the large intestine. This binds and opens chloride channels on the epithilium surface.
    Cl ions flood out into the lumen, lowering the water potential. This draws water out of the epithilium cells by osmosis down a water potential gradient.
    This may lead to chronic diarrohoea(cant spell) or dehydration.
    To rehydrate the cells we use an oral rehydration solution which contains glucose and na+. These species are taken up by co transport in the small intestine region, lowering water potential of the epithilial cells, allowing reabsorbtion of water.
    Muchos Gracias
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    Can anyone help me work out what mark I need out of 100 tomorrow to get an A on my overall A level?

    I don't know exactly what marks I got on all the previous units, but I've been a few marks (say two or three) into the A grade on all the written ones, BIOL1, BIOL2 and BIOL4. On BIOL3, I got a mid C. And I feel like I've got at least a B on BIOL6.

    What mark do I need to get? I'm rubbish at working these things out.
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    I know this is sooo silly, but please can everyone tell me what they think the main synoptic points are to properly focus on? I'm really worried about this exam, yes I am aware it is 5 to 11
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    (Original post by b_a)
    Can anyone help me work out what mark I need out of 100 tomorrow to get an A on my overall A level?

    I don't know exactly what marks I got on all the previous units, but I've been a few marks (say two or three) into the A grade on all the written ones, BIOL1, BIOL2 and BIOL4. On BIOL3, I got a mid C. And I feel like I've got at least a B on BIOL6.

    What mark do I need to get? I'm rubbish at working these things out.
    What was your Overall ums for AS and for unit 4?
    What do you think you will get on unit 6?
 
 
 
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