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    Hi I am sitting my biology igcse this may and i've been going through lots of the past papers. I'm finding the designing experiments questions hard because I don't really know how to go about them, especially because they are not the experiments we did in class. Any help would be appreciated!!!
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    I find sometimes that I've forgotten exactly what to do in the experiment it's asking for. I suggest looking through the textbook for your board, all the experiments that come up in the exams are mentioned in the textbook.

    Tips to boost marks on experiment questions.

    - if you don't know exactly, try make one up.
    - name the independent variable and the dependant variable
    - name what you should keep constant, what you shouldn't change. (e.g temp or humidity or volumes)
    - always say "repeat the experiment and average the results"
    - if the test data suits it, say "plot a graph of..." and "draw the line of best fit"
    - if you're testing something and measuring data, such as the amount of CO2 given off. Say "use a gas syringe to measure the amount of gas produced, as it is more accurate".
    - Whenever you say to measure something, name with what instrument ("use a ruler to measure...", don't say "measure the length".

    The mark schemes nearly always award marks for saying "repeat and average". "use a ruler" "keep the X constant". So even if you've got the experiment wrong, you can bag some marks.

    I like to write my answers in bullet points, in steps. For example, a question may be:

    Describe an experiment to test how changing the temperature effects the rate of respiration of yeast.

    (I would first think about the variables)
    - Place a known amount of yeast solution into a boiling tube. Add a known amount of glucose into the boiling tube. Both must be constant in the experiment.
    (next I would describe the experiment, trying to be as accurate as possible)
    - Place the boiling tube upright in a water bath. Water bath's are more accurate. Use a thermometer to measure the temperature of the water. Keep the temperature constant at 10 degrees celsius and fit a gas syringe to the top of the boiling tube.
    - Start a stopwatch, and stop the stopwatch at 60 seconds. Record the amount of gas collected.
    (always say to repeat)
    - Repeat the experiment, keeping the amount of yeast and glucose constant. But increase the temperature by increments of 10 degrees celsius.
    (talk about what to do with the data... table...graph...average results)
    - Plot a graph of gas collected(cm^3) against temperature (degrees celsius) and draw a line of best fit.
    (say what you think the outcome will be and name any equations you could use)
    - The rate of reaction(cm^3 / s) = amount of gas collected(cm^3) / 60(s)
    (link to the question, provide an answer.)
    - There should be a postitive correlation - as the temperature increases, the amount of gas released increases, and therefore the rate of respiration increases. Until a certain point, as the enzymes become denatured, the yeast no longer respires.

    --------------
    That's my basic formula for answering experiment questions.
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    The way these questions are marked is by the acronym CORMS.

    C - control, what are you changing?
    So if you are looking at the effect of temperature on something you might set up experiments at varying different temperatures.

    O - organism, what organism will you use and how will you keep this constant between experiments?
    With plants, for example, you should state what you would keep constant about the plants, so age, size etc.

    R - reliability, how will you make your result reliable?
    Normally you would just write that you would repeat each experiment a certain number of times.

    M - measurement, how will you take measurements?
    Give a stated period of time for which you will leave the experiment, say what you will measure to show change/differences in different experiments. Normally two marks, one for time and one for measurement.

    S - standardize, what factors will you keep constant throughout the experiment?
    In an experiment about plants you might say that you would keep the light intensity, temperature, humidity etc. the same. This also normally has two marks available.
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    (Original post by SuchBants;[url="tel:63766269")
    63766269[/url]]I find sometimes that I've forgotten exactly what to do in the experiment it's asking for. I suggest looking through the textbook for your board, all the experiments that come up in the exams are mentioned in the textbook.

    Tips to boost marks on experiment questions.

    - if you don't know exactly, try make one up.
    - name the independent variable and the dependant variable
    - name what you should keep constant, what you shouldn't change. (e.g temp or humidity or volumes)
    - always say "repeat the experiment and average the results"
    - if the test data suits it, say "plot a graph of..." and "draw the line of best fit"
    - if you're testing something and measuring data, such as the amount of CO2 given off. Say "use a gas syringe to measure the amount of gas produced, as it is more accurate".
    - Whenever you say to measure something, name with what instrument ("use a ruler to measure...", don't say "measure the length".

    The mark schemes nearly always award marks for saying "repeat and average". "use a ruler" "keep the X constant". So even if you've got the experiment wrong, you can bag some marks.

    I like to write my answers in bullet points, in steps. For example, a question may be:

    Describe an experiment to test how changing the temperature effects the rate of respiration of yeast.

    (I would first think about the variables)
    - Place a known amount of yeast solution into a boiling tube. Add a known amount of glucose into the boiling tube. Both must be constant in the experiment.
    (next I would describe the experiment, trying to be as accurate as possible)
    - Place the boiling tube upright in a water bath. Water bath's are more accurate. Use a thermometer to measure the temperature of the water. Keep the temperature constant at 10 degrees celsius and fit a gas syringe to the top of the boiling tube.
    - Start a stopwatch, and stop the stopwatch at 60 seconds. Record the amount of gas collected.
    (always say to repeat)
    - Repeat the experiment, keeping the amount of yeast and glucose constant. But increase the temperature by increments of 10 degrees celsius.
    (talk about what to do with the data... table...graph...average results)
    - Plot a graph of gas collected(cm^3) against temperature (degrees celsius) and draw a line of best fit.
    (say what you think the outcome will be and name any equations you could use)
    - The rate of reaction(cm^3 / s) = amount of gas collected(cm^3) / 60(s)
    (link to the question, provide an answer.)
    - There should be a postitive correlation - as the temperature increases, the amount of gas released increases, and therefore the rate of respiration increases. Until a certain point, as the enzymes become denatured, the yeast no longer respires.

    --------------
    That's my basic formula for answering experiment questions.
    i think the tip u gave r great because i do the same exact things and my teacher also recommend the tips u gave
 
 
 
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