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    I've completely failed every exam ive taken and im panicking so so so much for tomorrow oh my god
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    (Original post by Ozil5)
    We've been told that chi squared is needed and it does say it is required on the spec. But I just learnt it now for the first time and it doesn't take too long so I'd recommend learning it anyway.

    Also, is the highest amount of marks for a single question 6 under the new spec?

    Thanks!
    Thanks but what on earth is chi squared? googled and still dont get it..
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    What came up on breadth?


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    Does anyone have the corrected notes on calculations? The ones emailed by ocr because it was wrong in the textbook


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    (Original post by violavenisis)
    No, it can unbind from the allosteric site. However, because they are always present they prevent you from reaching Vmax, as there is a chance that at least one is currently bound to an enzyme (which is why the graph for non-competitive inhibition does not level off at the same point as the standard graph).
    what is Vmax?????
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    (Original post by skwonc)
    what is Vmax?????
    Vmax is the maximum velocity (rate) at which a reaction can take place. So at high substrate concentrations, Vmax is reached when all of the enzymes are bound with substrate molecules.
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    Does anyone use the OCR endorsed by Oxford a level biology textbook ? If so do you know where the answers for the paper 2 style questions are ?
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    (Original post by Hmb28)
    Does anyone use the OCR endorsed by Oxford a level biology textbook ? If so do you know where the answers for the paper 2 style questions are ?
    See link: https://global.oup.com/education/con...ers/?region=uk
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    (Original post by violavenisis)
    Vmax is the maximum velocity (rate) at which a reaction can take place. So at high substrate concentrations, Vmax is reached when all of the enzymes are bound with substrate molecules.
    So is this also when the enzyme is operating at maximum turnover number?
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    Thank you so much !
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    Can someone explain the test for proteins and the whole cardiac cycle please
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    Also I don't understand the speedometer calculations
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    (Original post by essex_ellz)
    Can someone explain the test for proteins and the whole cardiac cycle please
    Test for proteins: This is called the biuret test. Peptide bonds form violet coloured compounds when mixed with Cu ions in alkaline solutions. Therefore:
    -mix (about 2-3cm^3) sample with equal parts sodium hydroxide (NaOH- this is alkaline)
    - add copper sulphate solution (CuSO4- this is your source of copper ions)

    The copper sulphate solution causes the whole mixture to turn blue, but after leaving it to stand for a few minutes, the solution will turn violet/purple. This means that peptide bonds are present (therefore a protein is present).


    Cardiac cycle: this is comprised of diastole (heart relaxation) and systole (heart contraction).

    The atria fill with blood, which causes pressure to build within the heart. This pushes blood out of the atria (atrial systole) down a pressure gradient into the ventricles of the heart (here the bicuspid and tricuspid valves snap shut- this is your 'lub' sound).

    At this point the ventricles are extremely full with blood, so the blood is then pushed out through the aorta via the contraction of the ventricles (ventricular systole). The blood is forced through, causing the semilunar valves to snap shut (this is your 'dub' sound- the closing of valves is due to the high pressure and it prevents back flow of blood). The volume and pressure of the blood in the heart is low after systole, and the pressure in the arteries is high (as blood has just been pushed through here by the heart).

    The heart relaxes, and the process starts again.
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    Do you think that there will be anything/much on translocation? Since they had that question about mass flow phloem whatever (I can't really remember the question haha), because I don't want to revise the whole thing really hard and have it not be there:/
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    (Original post by essex_ellz)
    Also I don't understand the speedometer calculations
    If by speedometer, you mean spirometer, then calculations are usually fine- you just need to remember a few things.

    ventilation rate= tidal volume x breathing rate

    Your tidal volume is the volume of air that moves in and out of your lungs when at rest- this is usually the smaller 'wiggle' of the graph (if that makes sense). You can find out what this is by looking at the scale on the y-axis.

    Breathing rate is the number of breaths you take (usually per minute). On a spirometer graph, this is the number of oscillations in a given time (when the graph moves up and down once, this is a breath in and out- the volume has increased and then decreased).

    Ventilation rate is a way of bunching this information all together- it's the total volume of air inhaled in one minute. So, the amount of air that you breathe, per breath (tidal volume), multiplied by how many times you breathe in and out in a minute (breathing rate).
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    (Original post by chloelaura27)
    Do you think that there will be anything/much on translocation? Since they had that question about mass flow phloem whatever (I can't really remember the question haha), because I don't want to revise the whole thing really hard and have it not be there:/
    Yeah there's still a high chance. There could be a 6 marker on transpiration so do try and learn it...

    "What you don't revise will be in the exam..."
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    (Original post by Hmb28)
    Does anyone use the OCR endorsed by Oxford a level biology textbook ? If so do you know where the answers for the paper 2 style questions are ?
    what page are the papers?
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    (Original post by Ozil5)
    So is this also when the enzyme is operating at maximum turnover number?
    Yep!
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    (Original post by Ozil5)
    We've been told that chi squared is needed and it does say it is required on the spec. But I just learnt it now for the first time and it doesn't take too long so I'd recommend learning it anyway.

    Also, is the highest amount of marks for a single question 6 under the new spec?

    Thanks!
    Where does the spec say chi squared?
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    (Original post by 4nonymous)
    Where does the spec say chi squared?
    It says it under the maths section
 
 
 
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