Final answer:
The correct term for microorganisms that live in or on the human body without causing harm is 'commensal flora'. This includes both the permanent resident microbiota and the temporary transient microbiota, which both play an essential role in human health and defense against pathogens.
Step-by-step explanation:
The microorganisms that normally live in or on the body without producing harm and can be either resident or transient are known as the commensal flora.
Resident microbiota consists of microorganisms that constantly live in or on our bodies. They are essential for human health as they occupy biological niches and thereby offer protection against the colonization of pathogenic microorganisms.
On the other hand, the term transient microbiota refers to microorganisms that are found in the human body only temporarily. Factors such as hygiene and diet can alter the composition of these resident and transient microbiotas.
Commensal flora are beneficial as they engage in mutualistic relationships with the host, often providing defense against potentially harmful pathogens by mechanisms such as competition for resources and production of substances harmful to pathogens, like changing the pH.