OCR AS Biology

Revision Notes

1.1.1 Experimental Design

Experimental Design

  • Planning is an essential part of experimental biology
  • Preliminary research can be very helpful when trying to design an experiment to investigate a particular theory or hypothesis
    • Preliminary means “to come before”
  • Researching other similar studies or experiments can help you with:
    • Choosing the appropriate apparatus
    • Using the correct techniques
    • Identifying variables
    • Controlling other variables
    • Recording and collecting data accurately
    • Processing and presenting data in a useful way
  • The choice of apparatus and techniques should be based on the science surrounding the issue being investigated
  • For example, when testing the effect of different pH levels on enzyme activity is crucial that you know:
    • How to quantify/measure enzyme activity accurately
    • What other conditions (variables) will affect the function of an enzyme
    • For example, if the temperature becomes too high all the enzymes will denature and the enzyme activity will be 0 (no matter what the pH level is)
  • Once the preliminary research has been completed then preliminary studies can be conducted to further aid the experimental design
  • These studies are very important for:
    • Identifying additional variables that affect the experiment
    • Finding the best way to control these variables
    • Deciding on the quantities and volumes of substances that are needed so that you do not run out of reactants/reagents
  • Any experiment conducted without preliminary research or studies is likely to be invalid as the other variables that affect the results in the experiment will not have been identified and controlled
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