Final answer:
Biochemical tests are used to identify prokaryotes by examining how bacteria respond to different nutrients in the media, helping to create a biochemical profile that can classify or identify the species. The correct option is C.
Step-by-step explanation:
The method used to identify prokaryotes by examining how bacteria respond to different nutrients in the media is biochemical tests.
These tests involve exposing bacteria to a variety of substrates and detecting the presence of certain metabolic products.
For example, testing whether a bacterium can ferment a particular sugar or utilize a specific compound as a source of nitrogen or carbon can provide important clues about its identity.
Assays for enzymatic activities, such as catalase or oxidase, and the ability of organisms to produce gas or reduce nitrate also contribute to the biochemical profile, or "fingerprint," which helps in classifying and identifying prokaryotes.
Gram staining is another useful technique in microbiology, however, it is primarily used to differentiate bacteria based on the physical properties of their cell walls.
This method distinguishes between Gram-positive and Gram-negative bacteria but does not directly inform about bacterial nutrition and metabolic responses. The correct option is C.