The prefix allo- indicates which meaning?

• A. Similar
• B. Different
• C. Equal
• D. Uniform

Answer: (B)

allo- signals “other” or “different.” That root comes from Greek allos, used in terms like allograft or allogeneic transplant (tissue from another person) and alloimmune reactions (immune responses to foreign tissue). Because allo- conveys a sense of difference rather than similarity or sameness, it represents “different” as the meaning. In contrast, prefixes like iso- denote equal, and homo- can denote same; the option about uniform isn’t the standard way to express this concept.