What defines serial dilutions in a solution?

Serial dilutions are a technique used to create a series of solutions with progressively lower concentrations of a solute. The defining feature of serial dilutions is that they involve a constant dilution factor applied repeatedly to achieve successive concentrations. This process results in a geometric progression of concentrations, where each dilution is a fixed fraction of the concentration before it.

For example, if you start with a 1M solution and dilute it by a factor of 10 repeatedly, the concentrations of the resulting solutions would be 1M, 0.1M, 0.01M, 0.001M, and so forth. This method is particularly useful in biochemical and microbiological applications, as it allows for precise control over concentration levels and helps in determining the effective dosage or concentration of substances like drugs or microbial cultures.

The other choices do not capture the essence of serial dilutions. Random sampling of solutes does not imply a systematic approach to concentration changes. A single dilution process would not create the series of concentrations involved in a serial dilution. Isolation of individual components is unrelated, as it pertains to separating substances rather than the gradual dilution of a single solution.