What aspect of liquid nitrogen makes it useful for microbiology?

The usefulness of liquid nitrogen in microbiology primarily stems from its extremely low temperature, which facilitates long-term storage of biological samples, including microorganisms. Storing samples at such low temperatures helps preserve their viability and biological activity by slowing down metabolic processes and effectively preventing cellular degradation. This allows researchers to maintain cultures for extended periods, ensuring that they can be accessed and utilized for future experiments or studies without losing their characteristics or genetic integrity.

The other options pertain to aspects that are not relevant to the primary application of liquid nitrogen in microbiology. For instance, inducing microorganism growth or measuring concentration does not align with the purpose of using liquid nitrogen. Similarly, while inoculation processes are essential in microbiology, liquid nitrogen does not play a direct role in those procedures. The storage capabilities of liquid nitrogen are what truly underline its significance in the field.