Serial Dilutions (OCR A Level Biology): Revision Note

Serial Dilutions

• Serial dilutions are created by taking a series of dilutions of a stock solution. The concentration decreases by the same quantity between each test tube

  • They can either be ‘doubling dilutions’ (where the concentration is halved between each test tube) or a desired range (e.g. 0, 2, 4, 6, 8, 10 mmol dm^-3)

• Serial dilutions are completed to create a standard to compare unknown concentrations against

  • The comparison can be:

    • Visual

    • Measured through a calibration/standard curve

    • Measured using a colourimeter

  • They can be used when:

    • Counting bacteria or yeast populations

    • Determining unknown glucose, starch, protein concentrations

Making serial dilutions