Final answer:
To properly dispose of a plate of bacteria, it should be placed in a biohazard waste container, following established biosafety practices and lab protocols.
Step-by-step explanation:
When disposing of a plate of bacteria that will not be used anymore, the correct protocol is to dispose of it in a biohazard waste container. This is in accordance with established biosafety practices in a microbiology laboratory. It's important to recognize the international symbol for biohazards and to follow the procedures for biohazard waste disposal, which includes sterilization by autoclave before disposal. This ensures that any potential pathogens are rendered harmless and do not pose a risk to sanitation workers, the public, or the environment.
Leaving it on the lab bench, pouring it down the sink, or putting it in the regular trash are all inappropriate disposal methods and could lead to contamination or the spread of bacteria. Always follow your lab's safety protocol and check with your instructor if you're unsure how to properly dispose of bacterial cultures.