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

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    how long are people going to take on the essay? i was thinking maybe 30-40mins?
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    im really confused about pcr use in genetic fingerprinting, NT text book says it amplifies th edna sample and then uses restriction endonucleases to break the sample up, so in pcr how big is the sample that is amplified? how do they choose it? and if it just a section of dna, in parent fingerprinting wont you need two dna sections, one from each chromosome?
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    (Original post by appleschnapps)
    Er, I'm assuming you're talking about the genetic modification bit? If so, you should be safe - the spec says 'The use of recombinant DNA technology to produce transformed organisms that benefit humans', and because it doesn't go in depth there I'd be surprised if you need to remember them in too much detail. Just try and remember some examples, and memorise the arguments for and against genetic modification if you have difficulty thinking of them off the top of your head.

    If you were talking about something else, please tell me what because I've completely missed it.
    nah i meant those long stages bout antibiotic resitant gene in plasmids......

    also got good idea guys, some1 pick 1 chapter and list key pricnicples behind it, that way we all revise

    Many thanks!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!11

    also doing 1 paper of bio 5 helped me so much in terms of knowin wat they lokin for after lookin at answers
    guna get A!!!!!!!!!!1
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    (Original post by Jasmine_009)
    Question!!!
    Some organisms are adapted for living in hot, dry environments.
    Explain what causes the activity of reptiles living in a desert to vary greatly over a twenty-four hour period.
    Temperature fluctuates over the time period, provoking different behavioural mechanism, i.e shade when hot, lying flat against ground when cold...

    iis that right? :/
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    (Original post by kingsmod1)
    nah i meant those long stages bout antibiotic resitant gene in plasmids......
    Ohhh. In which case, I think you need to just be able to understand the basic principles (which ones would have resistance, why might some of them not, etc.), and they'll give you most of the details in the context in the question. That's based on what I've seen so far, at least.
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    (Original post by appleschnapps)
    Ohhh. In which case, I think you need to just be able to understand the basic principles (which ones would have resistance, why might some of them not, etc.), and they'll give you most of the details in the context in the question. That's based on what I've seen so far, at least.
    oh i thoguht u before u had to memrosie every stage in the book..
    so they give u it
    all u hve to do is rmember concept
    only long marker is essay right???
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    (Original post by sammycjones)
    how long are people going to take on the essay? i was thinking maybe 30-40mins?
    30 mins at the start. But I'll leave the conclusion unfinished so I can add anything if I have extra time.
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    any master tips on essay guys , i havent practiced any yet lol

    just depends on topic i suppose, cant be that hard?
    ill jus look at A template, follo that lol
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    Hey guys...

    The thing is, i think i know my stuff (hopefully!) but im struggling being able to apply it to exam questions...like not being too sure on what the questions asking.

    Anyone got any advice plz?

    Thanks. Gd luck peeps!
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    (Original post by angel1992)
    im really confused about pcr use in genetic fingerprinting, NT text book says it amplifies th edna sample and then uses restriction endonucleases to break the sample up, so in pcr how big is the sample that is amplified? how do they choose it? and if it just a section of dna, in parent fingerprinting wont you need two dna sections, one from each chromosome?
    PCR is used before the restriction endonucleases, so PCR amplifies the entirety of the sample. This will probably be fairly small regardless in genetic fingerprinting. When using genetic fingerprinting in paternity tests, you're working on the basis that half the bands will match with the offspring - you're not specifically picking the paternal DNA in the first place.

    (Original post by kingsmod1)
    oh i thoguht u before u had to memrosie every stage in the book..
    so they give u it
    all u hve to do is rmember concept
    only long marker is essay right???
    As long as you remember the key features (e.g. replica plating if the antibiotic is going to kill the bacteria that have incorporated the plasmid), you should be fine. Can't help you with the number of marks per question thing though; we don't really have enough to go on yet.
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    Hey guys, I have a quick question.
    Can someone please explain to me how summation means synapses accurately process information, "finely tuning the response"? I understand the concept of summation just not how it has that effect
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    [QUOTE=flowerscat;32320547]
    (Original post by vickidougal)
    can anyone help me with a few of these please
    1) when histamine is release from WBC's, how does dilation of the aterioles/arteries help injured or infected cells?


    It allows the white blood cells (mostly macrophages) to travel to the site of infection and ingest the pathogens.


    2)does the breakdown of the pigment in rod/cone cells cause the production of a generator potential?

    Pigment in rod cells = rhodopsin = breaks down into retinal and opsin. Opsin binds to sodium ions channels in the upper part of the rod cell, causing it to close. This decreases the membrane potential in the rod cell (hyperpolarisation). It stops secreting neurotransmitter. The neurotransmitter, glutamate, is an inhibitory neurotransmitter. As soon as glutamate secretion stops, the bipolar cell becomes depolarised (generator potential) and sends an impulse down the optic nerve.

    None of this is required for the AQA syllabus.

    3) what is the second messenger model of adrenaline and glucagon action?

    Adrenaline (first messenger) binds to its receptor on the cell memberane forming a receptor-substrate complex. This activates enzymes located on the inside of the membrane, which result in ATP being converted to cyclic AMP (cAMP). cAMP is the second messenger, and activates enzymes responsible for converting glycogen to glucose. *It also stimulates the production of glucagon by the alpha-cells in the pancreas (*info not in AQA textbook)

    Adrenaline is produced during times of stress, when the muscles need a quick burst of energy.

    Glucagon is not an enzyme, it is an hormone that binds to the receptors on liver cells and results in the activation of enzymes that convert glycogen to glucose.
    thank you very much is adrenaline an enzyme then? i thought it was a hormone?
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    (Original post by vickidougal)

    thank you very much is adrenaline an enzyme then? i thought it was a hormone?
    It is a hormone.
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    Ould anyone mind doing a summary of totipotenct and gene expression? Also I'm quite stuck on the dna probs/sequencin section. Any helpp much appreciated. Thanks a lot
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    (Original post by hg3)
    Ould anyone mind doing a summary of totipotenct and gene expression? Also I'm quite stuck on the dna probs/sequencin section. Any helpp much appreciated. Thanks a lot
    What do you not understand? That's quite a big section
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    (Original post by LeBubbled)
    That's exactly what I wrote as well! The mark schemes are so dodgy...the specimen one got an action potential question completely wrong (said sodium channels diffuse out when an impulse arrives).
    :eek: are you serious?!
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    (Original post by Cyanohydrin)
    It is a hormone.
    how come adrenaline forms a substrate receptor complex with the receptor on the CSM then? i thought that only applied to enzymes when their active site binds to a substrate
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    (Original post by hg3)
    Ould anyone mind doing a summary of totipotenct and gene expression? Also I'm quite stuck on the dna probs/sequencin section. Any helpp much appreciated. Thanks a lot
    Totipotent cells are undifferentiated, meaning they can develop into ANY cell. Stem cells are totipotent and they are found in the lining of the small intestine, skin, and bone marrow. Also, fertilised eggs are totipotent, technically known as 'embryonic stem cells'. In plants, however, loads of their cells are totipotent, and this is why you can grow a plant from a cutting, but you can't grow a body from a leg!!

    Basically, because every cell in your body contains the same DNA, every cell has the potential to code for ANY protein. However, we don't want that, as for example, we don't need insulin to be coded for and made anywhere else other than beta cells. So...different genes in different cells are turned on or off (expressed/not expressed), depending on the cell function/requirements. This is called gene expression, and is controlled by preventing transcription or breaking down mRNA before it's translated.

    Hope this helps
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    (Original post by OriginOfShowbiz)
    Hey guys, I have a quick question.
    Can someone please explain to me how summation means synapses accurately process information, "finely tuning the response"? I understand the concept of summation just not how it has that effect
    summation means the body can respond to smaller stimuluses, because the threashold level for neurotransmitter/ action potential can be exceeded more easily, so it's more finely tuned so to speak
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    Do we have to know photosynthesis and respiration in as much detail as we did for the january unit for synoptic essays? Because I can only remember the basic equations
 
 
 
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