Bacteria that live in or on another organism in a beneficial relationship are called what?

Bacteria that live in or on another organism in a beneficial relationship are called what?

• A. Pathogenic bacteria
• B. Symbiotic bacteria
• C. Normal flora
• D. Commensal bacteria

Answer: (B)

Living in a close, beneficial relationship with another organism is called symbiosis. Bacteria that do this—such as gut microbes aiding digestion or nitrogen-fixing bacteria in plant roots—are symbiotic because both partners benefit. Pathogenic bacteria harm the host, which is the opposite of beneficial. Normal flora are the microbes that normally inhabit the body and are often harmless or helpful, but the term doesn’t itself specify a beneficial partnership in the way symbiosis does. Commensal bacteria benefit themselves while the host is not helped or harmed, which isn’t the same as a clearly beneficial relationship. So the best term for bacteria in a beneficial relationship is symbiotic.

Living in a close, beneficial relationship with another organism is called symbiosis. Bacteria that do this—such as gut microbes aiding digestion or nitrogen-fixing bacteria in plant roots—are symbiotic because both partners benefit. Pathogenic bacteria harm the host, which is the opposite of beneficial. Normal flora are the microbes that normally inhabit the body and are often harmless or helpful, but the term doesn’t itself specify a beneficial partnership in the way symbiosis does. Commensal bacteria benefit themselves while the host is not helped or harmed, which isn’t the same as a clearly beneficial relationship. So the best term for bacteria in a beneficial relationship is symbiotic.