Texas A&M University (TAMU) BIOL206 Introductory Microbiology Lab Practice Exam 1

The streak plate method is a fundamental technique in microbiology primarily used for isolating pure colonies from mixed cultures. This method involves spreading a diluted microbial sample across the surface of an agar plate using an inoculating loop, creating distinct, isolated colonies that arise from single cells. By doing so, microbiologists can effectively separate specific microorganisms from a heterogeneous mixture, which is essential for studying individual species and their characteristics.

The ability to isolate pure colonies is crucial for various applications, including identifying microbial species, performing biochemical tests, and conducting susceptibility testing. Each colony that develops can be traced back to a single cell, providing researchers with a pure sample that can be cultured further.

In contrast, the other options, while relevant to microbiology, do not accurately describe the primary purpose of the streak plate method. The technique is not focused on measuring growth rates or quantifying concentrations of microorganisms, nor does it aim to eliminate all microbial life, as its intention is not sterilization but isolation of pure cultures for further investigation.