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    (Original post by flower123456)
    Anyone know a way to remember the kerbs cycle using mnemonics etc.
    draw it out in a diagram and memorise the picture - thats how i remember it)
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    (Original post by Mjwilson1988)
    http://mrhardy.wikispaces.com/file/v...spirometer.jpg

    Set up the apparatus as above, Tube A is the active tube with the woodlice (in this picture it is a stick insect, whatever you want really). Tube B is the control tube, and is there to ensure the results are just because of the woodlice.

    Use the syringe to push the liquid to a known starting point, this starting point must be the same for every repeat to ensure that your results are reliable and you end up with a valid conclusion.

    Set off a stop watch for a specific period of time (i.e. 10 minutes).

    Use the calibrated scale to measure the distance moved by the liquid, the liquid will move because as the woodlice respire, O2 is taken in and not replaced (Potassium Hydroxide will absorb CO2 produced from respiration and we do this so that we can more accurately measure the volume of O2 taken in, otherwise CO2 would go back into the tubes and alter the position of the liquid), so the volume of air on the side of the woodlice is reduced, reducing the pressure, causing the liquid to move towards Tube A. This is the amount of O2 used by the woodlice in 10 minutes.

    We can now calculate the volume of O2 used per min by dividing the volume used by the period of time the experiment was done over, example, a volume of 15cm3 was used in period of 10 minutes, so 15/10 is 1.5 cm3 per min.

    Repeat under exact same conditions, ensuring that temp is the same and the Mass of the woodlice you use is the same (you've just gotta name one variable to keep constant and that is a mark!)

    Take an average of your results to calculate a mean rate of respiration.

    Get an A* on the exam.

    Celebrate.
    Thanks
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    (Original post by Mollymod)
    So if I understand correctly, the calculation is
    (seconds in a minute which is 60) divided by the number of seconds on the trace multiplied by the number of beats in that time?
    Exactly, but you don't need to use the whole trace scale to work it out, if I saw that I had 3 beats in 5 seconds, I could easily get an answer of (60/5) x 3 = 36bpm.

    Or if I had 7 beats in 3 seconds I'd do (60/3) x 7 = 140bpm (this person is running for their life!
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    (Original post by Lujain Al Omari)
    Too little exercise: obesity, unfavourable waist to haip ratio and LDL to HDL ratio, increased risk of CHD, weaker immune, cardiac, respiratory and skeletal system. Less mental and emotional well being.

    Too much exercise: risk of muscoskeletal damge (straining, breaking ligaments...)
    weakened immune response:1) less T helper cells, so less cytokines, antibodies, active T killer cells
    2) adrenaline causes inflammation and suppresses the immune response
    and thats it? that simple?
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    (Original post by Nilie)
    and thats it? that simple?
    yup
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    so i did and the mark scheme had "3.5 x 10-3 ÷ 1.7 x 10-6" but the answer was "2059 {million / x 10 6 }/ 2058.8 {million / x 10 6 } / 2 058 823 530 ;" ???
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    (Original post by Nilie)
    and thats it? that simple?
    Yeah pretty much, they might ask you why there is an increased risk of CVD (such as stroke and Heart attack etc), then you need to go into detail about increased fatty deposits and atheroma formation leading to blockage, raised blood pressure, stress on artery wall leading to possible breakage and blood clot.

    That list is just the possible results of little or too much exercise, each little point can be expanded on in subsequent questions!
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    (Original post by Lujain Al Omari)
    yup
    fantastic) thanks a lot!
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    (Original post by Volltorb)
    so i did and the mark scheme had "3.5 x 10-3 ÷ 1.7 x 10-6" but the answer was "2059 {million / x 10 6 }/ 2058.8 {million / x 10 6 } / 2 058 823 530 ;" ???
    I think I know where you're going wrong buddy, the question says:

    "Myosin molecules can generate a force of 1.7 × 10–6 N per million molecules when they change shape."

    Therefore you've got to do the calculation (3.5x10-3) / (1.7x10-6) then all that multiplied by 1,000,000 which gives you '2,058,823,529' or 2,059,000,000 (which is 2059 million)
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    (Original post by Nilie)
    draw it out in a diagram and memorise the picture - thats how i remember it)
    Thank you
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    (Original post by Mjwilson1988)
    I think I know where you're going wrong buddy, the question says:

    "Myosin molecules can generate a force of 1.7 × 10–6 N per million molecules when they change shape."

    Therefore you've got to do the calculation (3.5x10-3) / (1.7x10-6) then all that multiplied by 1,000,000 which gives you '2,058,823,529' or 2,059,000,000 (which is 2059 million)
    Right thanks, but i cant believe the mark scheme didn't have 1 million anywhere.

    Also dose not the 1.7 × 10–6 force created imply its made by that 'per million'?
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    The amount of effort and revision i have put into this exam better pay off!
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    (Original post by Mjwilson1988)
    Exactly, but you don't need to use the whole trace scale to work it out, if I saw that I had 3 beats in 5 seconds, I could easily get an answer of (60/5) x 3 = 36bpm.

    Or if I had 7 beats in 3 seconds I'd do (60/3) x 7 = 140bpm (this person is running for their life!
    Sweet. Many thanks.
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    you see a control testube in the respirometer practical, would you use glass beads or no organisms at all ? please
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    Guys, how do you describe the production of genetically modified organisms (for plants, animals and microorganisms) by the use of drugs? could you please explain it to me. thanks in advance


    Also i'm wondering is anyone here taking Chem 5 on wednesday? :confused:
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    (Original post by jojo1995)
    you see a control testube in the respirometer practical, would you use glass beads or no organisms at all ? please
    Beads with the same mass as the woodlice.
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    (Original post by jojo1995)
    you see a control testube in the respirometer practical, would you use glass beads or no organisms at all ? please
    I'd choose glass beads, because there WOULD be something. And to make it a convincing control, use glass beads of the same number and size
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    (Original post by bubblegummer)
    Anyone here taking Chem 5 on wednesday? :confused:
    F324 yes
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    (Original post by Volltorb)
    Right thanks, but i cant believe the mark scheme didn't have 1 million anywhere.

    Also dose not the 1.7 × 10–6 force created imply its made by that 'per million'?
    No, that is just the number that has been registered, fairly unfortunate that it is the same as million! if you want to know how much force per one molecule of myosin it would be 1.7 x 10 -12, then you could divide 3.5x10-3 by that and get the same answer.
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    For naked mole rat do we need to know how blood clots form ?


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