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    (Original post by mikey_g)
    I thought the cerebellum did that!
    lol probably a typo. You are correct, indeed, the cerebellum is responsible for the movements of bones and balance.
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    http://www.youtube.com/watch?v=rFLssJ2n5FY

    a very good video on succession
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    oh god.. here I am waking up after 15 hours ****** sleep WTF... I really need to sort this **** out...
    I am finding f212 such a primitive module that I cba to revise yet I know I will probably **** it up if I dont do any revision.
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    (Original post by mikey_g)
    I thought the cerebellum did that!
    Misspelling, it is the cerebellum, i was tired :P
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    hey anyone know what cytokinins and abscinsic acid are used for??
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    (Original post by s_a_r_a)
    hey anyone know what cytokinins and abscinsic acid are used for??
    Cytokinins commerically is used to delay leaf senenscence and mass produce plants because they stimulate bud and shoot growth.

    you dont need to know abscissic acid uses, i dont think.
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    thank youuuuu.
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    (Original post by ibysaiyan)
    oh god.. here I am waking up after 15 hours ****** sleep WTF... I really need to sort this **** out...
    I am finding f212 such a primitive module that I cba to revise yet I know I will probably **** it up if I dont do any revision.
    I'm like this.. finding it really hard to get motivated and actually do it.
    Put SO much work into the 3 other exams and now it's kind of like on the home run and I'm running out of steam lol. :eek3:

    There's quite a lot to cram in. The last exam, photosynthesis, respiration, excretion etc.. It was all linked in some way whereas this one almost seems an afterthought of stuff they've thought.. 'ohh we better chuck this in so they know this that and the other'.. or is that just me :confused: Just seems a bit of a jump from brain to plant hormones to genetics lol
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    can anyone give me an example of a denitrifying bacteria?

    (brownie points on a question about the nitrogen cycle :love: )
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    can anyone please help with ways of measuring energy flow in ecosystem ,the green back goes on about a complicated experiment which i dont understand ???????...
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    (Original post by Archen)
    can anyone give me an example of a denitrifying bacteria?

    (brownie points on a question about the nitrogen cycle :love: )
    The bacteria is called Pseudomonas, it does denitrification in waterlogged soils as it uses nitrates as a source of oxygen and converts it by reduction to N2 and N2O gas.
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    (Original post by MG.GULED)
    can anyone please help with ways of measuring energy flow in ecosystem ,the green back goes on about a complicated experiment which i dont understand ???????...
    2 Main Ways of measuring energy flow

    1) Measure the dry mass of organisms - heat the organism to about 80 degrees C, till all water has evaporated and then measure the dry mass. however this can prove destructive to the ecosystem and damage habitats so they usually measure wet mass and calculate dry mass using previous data

    2) Heat the organisms in a calorimeter - Burn them at high temperature, this directly measures the energy in them...the energy released is used to heat up a known mass of water and so the energy released can be calculated from this but again, destructive to habitats/ecosystems so usually use pyramids of biomass.

    I think thats what you meant? O.o
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    can anyone please help with the events leading up to leaf abscission??? ive got 2 revision guides telling me completely different things!! one which tells me that abscissic acid stimulates the production of ethene which leads to breakdown of middle lamellae in the cell walls in cells at the base of the petiole while the other book tells me its the decrease in auxins which causes the increase in ethene which stimulates enzyme cellulase. sooo confused!!!
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    (Original post by MG.GULED)
    can anyone please help with ways of measuring energy flow in ecosystem ,the green back goes on about a complicated experiment which i dont understand ???????...
    there are two ways to measure energy in an ecosystem

    first, which i assume is the experiment you are referring to, is a calorimetry experiment.
    this is where you directly measure the amount of energy in joules by burning the organism in a calorimeter and the amount of heat given off tells you how much energy is in them
    i doubt you need to know the ins and outs of the experiment as long as you know that you use and calorimeter and burn the organism


    second would indirectly measure the energy by measuring an organisms dry mass (i.e. their biomass)
    Biomass is created using energy so its an indicator of how much energy an organism contains
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    (Original post by ihatemathsandmore)
    can anyone please help with the events leading up to leaf abscission??? ive got 2 revision guides telling me completely different things!! one which tells me that abscissic acid stimulates the production of ethene which leads to breakdown of middle lamellae in the cell walls in cells at the base of the petiole while the other book tells me its the decrease in auxins which causes the increase in ethene which stimulates enzyme cellulase. sooo confused!!!
    As far as im aware, abscissic acid ISNT in leaf abscission, it was only named so because it was believed to be.

    Basically, when young, the leaf produces cytokinins and auxin which delay leaf senescence. As it gets older auxin and cytokinins production decreases and ethen production increases. This allows cellulase enzymes to be activated which produces an abscission layer which separates the leaf petiole from the stem (then enzymes can cause expansion of cell walls in the leaf which causes it to 'fall' off).

    Im not sure you need to go into such detail with lamellae in cholorplast etc.

    Lol thanks for the +rep btw archen.
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    (Original post by Falcon91)
    As far as im aware, abscissic acid ISNT in leaf abscission, it was only named so because it was believed to be.
    I think you're right there, but I'm also pretty sure I've read somewhere that abscissic acid promotes abscission in some plants, and in others it prevents it :confused:
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    (Original post by TheMikester69)
    I think you're right there, but I'm also pretty sure I've read somewhere that abscissic acid promotes abscission in some plants, and in others it prevents it :confused:
    No. Basically what you get is that in old leaves low auxin is produced which makes them more sensitive to ethylene as a result of which auxin production completely stops (inhibits) so... this ethlyene causes leaf abscission not the acid =}
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    Explain with aid of diagrams and photographs, the sliding filament model muscular contraction.
    Outline the role of ATP in muscular contraction and how the suppy of ATP is maintained in muscles.

    I'd appreciate soo much if anyone can summarise these two points for me. I've written my notes out 3 times, and I really just can't get my head around it
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    (Original post by nbailey8)
    Explain with aid of diagrams and photographs, the sliding filament model muscular contraction.
    Outline the role of ATP in muscular contraction and how the suppy of ATP is maintained in muscles.

    I'd appreciate soo much if anyone can summarise these two points for me. I've written my notes out 3 times, and I really just can't get my head around it
    for ATP:
    1. aerobic respiration - normal stuff, oxidative phosphorylation yada yada
    used for long muscle use low levels of exercise e.g. walking
    2. anaerobic respiration - lactate pathway etc
    produces ATP but doesnt last very long because of lactate build up e.g. sprint
    3. ATP-Phosphocreatine -ADP is phosphorylated to ATP by phosphocreatine PCr
    this is alactate (no lactate produced) and anaerobic
    it provides lots of ATP but is used up quickly e.g. tennis serve

    ATP is used in muscle contraction to:
    move myosin heads (bend them so the myosin slides over the actin filament)
    break actin-myosin cross bridges
    active transport of Ca2+ ions out of the sacroplasm AFTER muscle contraction


    hope this helps
    i find it great revision explaining stuff to people
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    (Original post by TheMikester69)
    I think you're right there, but I'm also pretty sure I've read somewhere that abscissic acid promotes abscission in some plants, and in others it prevents it :confused:
    abscisic acid (ABA)
    closure of stomata/ stress hormone which prevents excess water loss
    inhibiting of protein pump

    abscission of leaves/fruits

    promotes seed dormancy/ inhibits germination
    prevents production of enzymes


    this is taken from the mark scheme of the central concepts jan 2005 paper
    the question was just to name two plant hormones and their effects
    this is what the mark scheme said for abscisic acid
    hope this helps
 
 
 
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