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    (Original post by ViolinGirl)
    Hmm. I can't immediately think of many similarities but here goes...

    They are both separation techniques that relate to the size of the items present in the sample.
    They both require a medium in which the sample travels through.
    In both cases separation depends on the affinity the sample has for the stationary phase (the phase does not move) and this governs how fast/slow it moves across it (the mobile phase). For example in electrophoresis, the agrarose gel is the medium through which the fragments of DNA travel through. Longer pieces of DNA can be considered to have more affinity for this stationary phase and they will move through the agrarose gel less easily that shorter pieces.
    With both techniques you can conduct further analysis on the sample, in electrophoresis you can transfer sample to paper, by southern blotting, use probes to locate certain genes etc. With Chromatography, values can be looked up, and used to identify the unknown substances, e.g. RF values.

    Lol, I've done this more in terms of chemistry.
    I can't think of more...

    That's one crazy answer! much better than the book, but here's what sue hocking has to say;

    "electrophoresis is very like chromatography in that materials are separated by size. the separating mechanism is a balance between 'retardation' against solubility. solvent is used in chromotography, electric charge across buffer solution used in electrophoresis"

    ooh and with the dopamine point, CGP gives a somewhat controversial answerr, but its the closest ive found to what the specification wants:

    "much of our understanding of human behaviour comes from studying people with abnormal behaviour, to see how their brains are different from the people who behave 'normally'

    so any differences (e.g. in abundance of D4 receptors) may give clues to how normal behaviour is controlled". this is supposedly the case with schizophrenia . the link between too many d4 and abnormal behaviour implies d4 has something to do with normal behaviour too

    goddamn biology :/
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    (Original post by ViolinGirl)
    A use for artifical auxins is that they can be used as herbicides, and the desription is that they are uptaken by the weeds, and transported to all parts of the plant, and as they are not a close fit to the enzymes present in the plant, as they are artifical, they will act for longer causing over elongation and the stem to buckle and plant to die.

    But why does this only affect the weeds? if sprayed onto crops and weeds alike, then what is preventing the same thing happening to the crops?
    That is a very GOOD question, just made me think... how would a herbicide recognise that a weed is present. May be its specifically sprayed on weeds - as I would think humans can only detect whats a weed and whats not
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    (Original post by ViolinGirl)
    I need help on this one- please explain this dopamine stuff (bullet points would be appreciated)!
    Dopamine

    - Can act as a neurotransmitter or a hormone
    - Precursor for the production of noradrenaline and adrenaline
    - Low levels - cause difficulty in initiating movement e.g. Parkinsons disease.
    - High levels - been linked to mental health problems e.g. Schizophrenia.
    - Increases general arousal and decreases inhibition.

    - There are 5 dopamine receptors - each codes for a separate gene
    - Binding of domanine to a receptor is used in many processes e.g. the control of learning and motivation
    - Antipsychotic drugs - block dopamine receptors.

    DRD4 receptor gene

    - inhibits adenyl cyclase
    - variable human genes
    - repeats of 48 base pair sequences
    - each repeat >> changes the primary structure of the protein >> alters the 3-D shape of the receptor >> alters the ability to bind to dopamine.
    - e.g. ADHD, addictive and risk behaviour (smoking, gambling).
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    (Original post by student92)
    That is a very GOOD question, just made me think... how would a herbicide recognise that a weed is present. May be its specifically sprayed on weeds - as I would think humans can only detect whats a weed and whats not
    i was thinking about this too..
    but we have just sprayed our whole lawn with a herbicide to kill the daisies - it makes them grow really fast and die (obv. synthetic auxin)
    so why does it not kill the grass?
    my dad certainly did not go round spraying every individual daisy.. :s
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    (Original post by la_doo)
    Hi

    Does anyone have a summary on genetic engineering of Golden Rice? or someone could kindly identify the main points, ive got one but its slightly wordy and hard to remember.

    Thanks
    Engineering golden rice

    1) 2 genes from a dafodil and 1 gene from a bacterium - Urwinia Udovara are inserted into a Ti plasmid
    2) Plasmid is taken up by the bacterium - Agrobacterium Tumefacien
    3) Gene is introduced to rice embryos
    4) Gene is transcribed and translated in the endosperm - which produces a protein that synthesises a beta-carotene giving the endosperm a yellow/orange colour, hence golden rice.
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    (Original post by Archen)
    i was thinking about this too..
    but we have just sprayed our whole lawn with a herbicide to kill the daisies - it makes them grow really fast and die (obv. synthetic auxin)
    so why does it not kill the grass?
    my dad certainly did not go round spraying every individual daisy.. :s
    http://www.wisegeek.com/how-do-weed-...-not-lawns.htm

    Not really up to A-level biology answer, but it gives an ideaa? maybe the weeds have particular enzymes which grass doesn't, so it only effects the weeds or something....?
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    (Original post by Archen)
    i was thinking about this too..
    but we have just sprayed our whole lawn with a herbicide to kill the daisies - it makes them grow really fast and die (obv. synthetic auxin)
    so why does it not kill the grass?
    my dad certainly did not go round spraying every individual daisy.. :s
    Well specific herbicides I guess - something about target enzymes within the weed, I read somewhere.
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    (Original post by student92)
    Well specific herbicides I guess - something about target enzymes within the weed, I read somewhere.
    I was going to say the same, they only act on certain target cells just as human hormones do, so they will probably bind to specific receptors only found in weeds or their enzymes or something like that...

    But then again, this is why you breed in herbicide rsistance to plants you dont want to get killed by the action of over-stimulation of shoot growth due to auxin although these are synthetic auxins.
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    :s
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    Hey guys heres a specification point thats been annoying me for a while:

    "Outline how energy transfers between trophic levels can be measured?"

    There's a lot of blah in my textbook, does anyone have any quick bullet points about it? Cheers
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    (Original post by radical07)
    Hey guys heres a specification point thats been annoying me for a while:

    "Outline how energy transfers between trophic levels can be measured?"

    There's a lot of blah in my textbook, does anyone have any quick bullet points about it? Cheers
    These are my notes:

    Measuring energy transfers between trophic levels

    This is hard to do in the wild because many uncontrollable variables produce unreliable results. Measurements are therefore carried out in an artificial laboratory situation.
    1. The food chain is worked out
    2. The population size of each species is measured. For lab measurements, sampling is involved.
    3. Mean dry mass of a single organism is calculated by killing a sample of organisms and drying it to constant mass.
    4. The energy content per gram of dry mass is calculated for each kind of organism by doing an enthalpy calculation.
    --> sample of dry material of known mass is burned in a colorimeter and heat produced is measured

    5. total energy content in population = no. of organisms x mean dry mass of one organism x energy content of 1 g od dry mass.


    Hows everyones rev going?

    Quick Q : Does anyone have a linke for a good website for labelling and learning parts of the brain? Some sort of interactive one. And any good ways of learning it? :o:
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    Anyone have a list of ALL the definitions we need to know?
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    (Original post by Falcon91)
    I was going to say the same, they only act on certain target cells just as human hormones do, so they will probably bind to specific receptors only found in weeds or their enzymes or something like that...

    But then again, this is why you breed in herbicide rsistance to plants you dont want to get killed by the action of over-stimulation of shoot growth due to auxin although these are synthetic auxins.

    I think it's also because it's usually grass species that it's used on, and because the apicial bud is so low to the ground, just above the roots it's not effected by the auxins
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    (Original post by radical07)
    Hey guys heres a specification point thats been annoying me for a while:

    "Outline how energy transfers between trophic levels can be measured?"

    There's a lot of blah in my textbook, does anyone have any quick bullet points about it? Cheers
    Was just studying this today, it can be measured (or more simply compared), in 3 ways;

    Pyramids of Biomass
    -The area of the bars is proportional to the dry mass at that specific trophic level.
    -This is measured by heating all the organisms to 80 degrees, until all the water is evaporated, and weighing the resulting mass.
    -This is destructive, so usually ecologists just take the wet mass.

    Pyramids of Energy
    -Similar to Pyramids of Biomass, but involves burning the organisms in a calorimeter.
    -This calculates the amount of heat energy released per gram of that organism, (and therefore the amount of energy contained within that organism's trophic level).
    -This is a more accurate representation of the efficiency of energy transfer.
    -Though this is more destructive and difficult, so ecologists often refer to using Pyramids of Biomass instead.

    Productivity
    -This is the rate at which energy passes through each trophic level in a food chain.
    -Productivity is determined by measuring the amount of energy available to an organism's trophic level, per unit area (square metre), in a given time (usually one year), and is measured in kilojoules, (or more commonly megajoules).
    -The productivity of the producers (plants, and some photosynthetic bactera and algae) is called the primary productivity --->:eek:
    -Gross primary productivity is the rate at which producers convert light energy into chemical energy.
    -Though, these producers must respire, resulting in less energy being transferred to the primary consumer's trophic level.
    -The remaining energy is called the net primary productivity, (or if you like the NNP).

    Hope this helps.
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    I got scared/had a biology crisis when i was chilling so i decided to go over a few pages of the spec for module 1 and some of 2. Thank god i had most of it
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    (Original post by zoop)


    Hows everyones rev going?

    Quick Q : Does anyone have a linke for a good website for labelling and learning parts of the brain? Some sort of interactive one. And any good ways of learning it? :o:

    http://northernrockiesneurosurgeons.com/brain.htm

    found this one alright
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    (Original post by zoop)
    Quick Q : Does anyone have a linke for a good website for labelling and learning parts of the brain? Some sort of interactive one. And any good ways of learning it? :o:
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    (Original post by Sakujo)
    At first i thought it was just going to reference pinky and the brain, but that was actually useful lol, brilliant find. +rep for you
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    (Original post by Sakujo)
    Hehe my friend sent that to me, its great!

    Well I've made my own labelling diagram cos I couldn't find one off the net for the brain so if anyone wants a copy pm me your e-mail address and I'll send it on. Its just the textbook but edited. x
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    (Original post by zoop)
    These are my notes:

    Measuring energy transfers between trophic levels

    This is hard to do in the wild because many uncontrollable variables produce unreliable results. Measurements are therefore carried out in an artificial laboratory situation.
    1. The food chain is worked out
    2. The population size of each species is measured. For lab measurements, sampling is involved.
    3. Mean dry mass of a single organism is calculated by killing a sample of organisms and drying it to constant mass.
    4. The energy content per gram of dry mass is calculated for each kind of organism by doing an enthalpy calculation.
    --> sample of dry material of known mass is burned in a colorimeter and heat produced is measured

    5. total energy content in population = no. of organisms x mean dry mass of one organism x energy content of 1 g od dry mass.


    Hows everyones rev going?

    Quick Q : Does anyone have a linke for a good website for labelling and learning parts of the brain? Some sort of interactive one. And any good ways of learning it? :o:

    (Original post by Alex-92)
    Was just studying this today, it can be measured (or more simply compared), in 3 ways;

    Pyramids of Biomass
    -The area of the bars is proportional to the dry mass at that specific trophic level.
    -This is measured by heating all the organisms to 80 degrees, until all the water is evaporated, and weighing the resulting mass.
    -This is destructive, so usually ecologists just take the wet mass.

    Pyramids of Energy
    -Similar to Pyramids of Biomass, but involves burning the organisms in a calorimeter.
    -This calculates the amount of heat energy released per gram of that organism, (and therefore the amount of energy contained within that organism's trophic level).
    -This is a more accurate representation of the efficiency of energy transfer.
    -Though this is more destructive and difficult, so ecologists often refer to using Pyramids of Biomass instead.

    Productivity
    -This is the rate at which energy passes through each trophic level in a food chain.
    -Productivity is determined by measuring the amount of energy available to an organism's trophic level, per unit area (square metre), in a given time (usually one year), and is measured in kilojoules, (or more commonly megajoules).
    -The productivity of the producers (plants, and some photosynthetic bactera and algae) is called the primary productivity --->:eek:
    -Gross primary productivity is the rate at which producers convert light energy into chemical energy.
    -Though, these producers must respire, resulting in less energy being transferred to the primary consumer's trophic level.
    -The remaining energy is called the net primary productivity, (or if you like the NNP).

    Hope this helps.
    Cheers guys very useful. does anyone else find it weird the way organisms are just burnt for the purpose of ecology? I would have thought the textbook would be screaming moral issues but they talk about it so casually!
 
 
 
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