Final answer:
A nutrient agar slant is used to grow and maintain bacterial cultures over an extended period, allowing for the observation of colony characteristics and the preservation of bacterial species.
Step-by-step explanation:
A nutrient agar slant is used in microbiology to grow and maintain cultures of bacteria over a period of time. By inoculating a slanted agar surface with bacteria, one can observe colony characteristics such as texture, transparency, and pigmentation. Additionally, agar slants provide a longer-term substrate for bacteria compared to Petri dishes, which may dehydrate over time. Cultures on slants can remain viable for weeks or even months, especially when refrigerated. This allows for the preservation and subculturing of bacterial species for future study and experimentation.